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Assessment of Mercurity Toxicity Hazard Associated with Former Cinnabar Mining and Tailings Disposal in Honda Bay, PalawanT M Williamd, J M Weeks, A Apostol, C MirandaBritish Geological SurveyWC/96/31/R
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BRITISH GEOLOGICAL SURVEY
TECHNICAL REPORT WC/96/3 1/R Overseas Geology Series
Assessment of mercury toxicity hazard associated with former cinnabar mining and tailings disposal in Honda Bay, Palawan, Philippines.
T M Williams', J M Weeks2, A Aposto13 & C. Miranda'
1 : British Geological Survey, Keyworth, Nottingham, UK. 2: Institute of Terrestrial Ecology, Monks Wood Station, Cambs. UK. 3: Mines and Geosciences Bureau, Diliman, Quezon City, Philippines
A report prepared for the Overseas Development Administration Engineering Division under ODA-BGS contract R6226: Mitigation of mining-related mercury pollution hazards.
ODA classification Subsector: Geoscience Theme: Identify and ameliorate minerals-related geochemical toxic hazards. Project title: Mitigation of mining-related mercury pollution hazards. Project Reference: R6226.
Bibliographic reference: T M Williams, J M Weeks, A Apostol and C Miranda 1996: Assessment of mercury toxicity hazard associated with former cinnabar mining and tailings disposal in Honda Bay, Palawan, Philippines. British Geological Survey, Overseas Geology Series Technical Report WC/96/3 1, Keyworth, Nottingham, UK.
Key words: Mercury, mining, tailings disposal, human health, toxicology.
Cover illustration: Former Palawan Quicksilver Mining Inc. operation, Santa Lourdes, near Puerto Princesa, Palawan,
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SYNOPSIS
An assessment of mercury (Hg) contamination and attendant human exposure associated with former cinnabar mining activities on the Philippine island of Palawan was undertaken by the British Geological Survey (BGS) in collaboration with the UK Institute of Terrestrial Ecology (ITE) and the Philippines Mines and Geosciences Bureau (MGB) in December 1995. The study followed a formal request from the Philippines Department of Environment and Natural Resources (DENR) for assistance in investigating media reports of human mercury poisoning near the former Palawan Quicksilver Mining Inc. (PQMI) operation at Santa Lourdes. Funding for the work was provided by the UK Overseas Development Administration (ODA) under Technology Development and Research (TDR) programme R6226: Mitigation of Mining-Related Mercury Pollution Hazards.
The aims of the study were (i) to establish the spatial extent and magnitude of Hg contamination within the marine environment of Honda Bay, eastern Palawan, (ii) to evaluate temporal trends of Hg deposition in marine sediments with particular reference to any flux adjustments associated with the onset of mining, (iii) to assess the risk posed to local populations as a consequence of living on or near a mine-waste substrate, (iv) to assess the extent of Hg bioassimilation and attendant toxicological stress in marine biota, and (v) to assess alternative (non mining-related) sources of Hg exposure including potable water.
Marine sediment cores were used to assess spatial and temporal trends of Hg deposition in Honda Bay. The average Hg concentration in surficial sediment at offshore sampling stations throughout the study area was found to be c. 40 pgkg, and is thus within the global background range. Downcore Hg profiles indicate no significant adjustment of Hg influx over the past c. 100 years.
Geochemical and mineralogical analyses of mine waste from the Sitio Honda Bay jetty structure were undertaken to establish the total concentration and bioavailability of Hg. Profiles through the waste characteristically display a depthward reduction of Hg concentration, from surficial values of up to 340 mgkg to basal concentrations of <40 mg/kg. The solid-phase speciation of Hg in the <2mm fraction of the waste is dominated by inorganic non-sulphide Hg-phases (generally constituting ~90% of the total Hg mass balance), These phases are of typically low bioavailability . Human Hg exposure through particulate inhalation or hand-mouth ingestion is therefore considered unlikely to be significant.
Analyses of aquifer- and stream water samples from the study area provided no evidence of Hg contamination, with values typically below 40 ng/l. The role of potable water as a source of human Hg exposure is thus likely to be negligible.
Mercury concentrations in six species of fish from Honda Bay were found to fall within the ranges typically encountered for analogous species worldwide. Median Hg values for all analysed species lie within the US- EPA marketing threshold of 0.5 mgkg. Mercury burden data for the shellfish P e w Viridis (green mussel) highlighted significant tissue Hg enhancement (to 21 mg/kg dry weight) in samples collected from within 10-20 m of the Sitio Honda Bay jetty. Concentrations in samples collected from a coral island c. 7 km offshore were found to fall within the global background range (c3 mgkg dry weight). Attendant toxicological stress in the Sitio Honda Bay samples has been inferred from neutral-red biomarker assays.
Human Hg body burdens were appraised for 130 Palawan subjects through the collection and analysis of hair samples. The results indicate that all Palawan residents are subject to high Hg exposure, relative to a control population from Manila. It is, however, unlikely that this is reflective of geological or mining influences. Statistical analysis of data for five Palawan sub-groups failed to significantly discriminate those living on a mine-waste substrate from and other populations. Estimated mean blood Hg values for the five sample groups ranged from 8.8 - 17.6 ng/ml, with a maximum individual value of 74.1 ng/ml. Such values am typical of populations consuming fish at a daily frequency. There i s virtually no evidence of appreciable toxicological risk at blood concentrations of this magnitude.
The data presented in this study do not substantiate the claims made in the Philippine media during August and September 1995 regarding the occurrence of a major mercury poisoning episode in Palawan. The conclusions of this study are, however, based largely on a single field sampling programme. Longer-term monitoring is recommended to gain a more comprehensive understanding of the sources, environmental behaviour and toxicity of Hg on the island of Palawan and elsewhere.
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1: INTRODUCTION
Research into the environmental and human impacts of mercury (Hg) contamination in the Philippines was initiated by the BGS in April 1995 as a component of an Overseas Development Administration (ODA) Technology Development and Research (TDR) programme R6226: Mitigation of Mining-Related Mercury Pollution Hazards. The fundamental aims of the programme are (i) to design and test a protocol for monitoring the spatial extent and magnitude of mining-related Hg contamination, (ii) to assess the human and toxicological significance of such contamination and (iii) to examine the potential for modifying mineral-processing technologies to reduce environmental Hg fluxes.
At the project outset, Eastern Mindanao was jointly identified by staff of the BGS and the Philippines Mines and Geosciences Bureau (MGB) as an appropriate focus for research due to the extensive gold-rush which has occurred in the region during the last two decades, with widespread utilisation of Hg for gold amalgamation. In August 1995, the MGB were, however, forced to reappraise their priorities in the light of widespread media reports of human mercury poisoning in an area of former cinnabar mining on the island of Palawan. In response to a directive from Philippines President Fidel Ramos, the MGB commissioned an inter-agency investigation into the Palawan scare, and a formal request for the diversion of BGS-ODA funds from Mindanao to Palawan was received by BGS in September 1995. Although falling strictly beyond the remit of TDR project R6226 (which is primarily concerned with Hg pollution associated with artisanal gold mining), the request was considered by BGS and ODA to constitute a strong case for demand-led TDR expenditure, Accordingly, a preliminary BGS-MGB investigation of the extent of the Palawan Hg problem was sanctioned in December 1995, and executed with assistance from the UK Institute of Terrestrial Ecology (ITE). This report outlines the results of this survey and their implications for future policy development within the area of concern.
2: STUDY AREA:
The area of reported human Hg risk on the island of Palawan encompasses three barangays (villages), Santa Lourdes, Sitio Honda Bay (SHB) and Tagburos (Fig. l), situated approximately 14 km north of Puerto Princesa (lat. 118"42'E, long. 09"JO'N). The area is drained by the Tagburos River, which flows in a south-easterly direction into Honda Bay. The coastal margin is characterised by low lying topography (e50 m), with an extensive marsh area occupying the lower 1 km of the Tagburos River floodplain. The coastal environment of Honda Bay is dominated by primary mangrove vegetation.
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Palawan, and the immediate provision of central government funds to support one or more of the following actions:- (i) detoxification of approximately 25% of the local population (based on the 25% failure of subjects in the preliminary DOH survey to meet the ‘normal’ blood threshold of 20 ng/ml), (ii) provision of a laboratory facility at Puerto Princesa Provincial Hospital for the analysis of Hg in blood, (iii) removal of the Sitio Honda Bay jetty and safe disposal of the contaminated tailings, (iv) resettlement of the c. 200 population of Sitio Honda Bay, (v) dredging of sediments from contaminated sectors of Honda Bay.
3.3: Areas of uncertainty:
By late 1995, the widespread publicity surrounding the Palawan mercury scare had imposed a significant economic impact on the island, notably its fishing industry as a consequence of concern over product quality amongst wholesale purchasers in Manila. Prior to the BGS/ITE survey, however, little quantitative data existed to show the genuine extent of ecotoxicological risk to populations living close to the PQMI mine, on the Sitio Honda Bay jetty, or those consuming fish from Honda Bay. Particular uncertainty may have arisen through the misrepresentation of the geochemical data of Benoit et al (1994) in the media which, in failing to emphasise the extremely localised nature of the study, inferred that anomalous Hg concentrations were characteristic of the entire Honda Bay floor. In reality, the gradients reported by Benoit et al(1994) show concentrations declining rapidly from 560 mgkg on the jetty, to 38 mgkg at 25 m distance, and 2.3-18.8 mgkg at a distance of 200 m. Data for control sites 7-10 km offshore indicate the prevalence of conditions within the global background range (0.03 - 0.2 mgkg).
Uncertainties in the preliminary biological and ecotoxicological datasets collated by the EMl3 and DOH primarily reflect the small sample populations involved. For example, the occurrence of ‘Minamata range’ Hg concentrations in fish and shellfish from Honda Bay reported by the EMB (and subsequently by the Philippine media) was based on the analysis of only 6 samples, collected in November 1994. Follow-up sampling of a further 6 fish samples by the EMB in May 1995 yielded Hg values at least an order of magnitude lower than those reported in 1994. While seasonal factors were invoked to account for this discrepancy, the inherent variability of trace metal concentrations in biological samples could have been equally influential.
The conclusions drawn from the DOH human blood survey of 42 subjects from the Honda Bay area could also be considered equivocal. Of the 12 subjects who yielded blood Hg values exceeding the 20 n g / d threshold, 50% were former miners or roasting plant operators. Data for these individuals do not therefore infer any wider exposure of the
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population via the food chain. Within this sub-group the highest recorded value (25 ng/ml) can be regarded as low for individuals subject to long-term occupational exposure. Although clinical symptoms of Hg poisoning have been observed in a limited number of Honda Bay miners, it is unlikely that these could have been caused by blood Hg levels of this magnitude. Reference data from a comprehensive UNEPNHO-endorsed Monitoring and Assessment Research Centre (MARC) study indicate that the lifetime exposure threshold required to induce symptoms of clinical Hg poisoning is 80 ng/ml, with effects typically absent at levels of c200 ng/ml. Clinical damage in miners could, however, have been caused by short-term exposure (no longer reflected in blood) up to several decades previously.
4: AIMS OF BGS-MGB-ITE STUDY
In view of the paucity of geochemical, ecotoxicological or epidemiological data depicting the extent or magnitude of Hg hazards in centraleastern Palawan, the central aims of the BGSATE study were:-
1: Establishment of the spatial extent and magnitude of Hg contamination within the sediments of Honda Bay 2: Evaluation of temporal trends of Hg deposition in the marine environment, with particular reference to flux adjustments associated with the onset of mining and the construction of the Sitio Honda Bay jetty. 3: Assessment of the risk posed to populations of Sitio Honda Bay jetty and the PQMI mine locality as a consequence of living on a mine-waste substrate (and hence the need to re-house such populations). 4: Assessment of the extent of Hg bioassimilation and attendant toxicological stress in marine biota (fish and shellfish) at various localities in Honda Bay, and appraisal of the significance of Sitio Honda Bay as a contaminant source for biota. 5: Assessment of alternative potential sources of Hg exposure (eg. potable water) 6: Preparation of recommendations for remedial action, if appropriate.
5: METHODOLOGY AND RESULTS
3.1 : Marine sediment study.
5.1.1: Sample selection: A survey incorporating 12 offshore gravity coring stations and numerous additional coastal auger sites in Honda Bay (Fig. 7) was undertaken by the MGB research vessel Explorer in September 1995. Cores of up to 4 m length were split lengthwise on return to the MGB laboratory in Manila, and sub-sampled to yield contiguous 10 cm stratigraphic sections. Analysis of total Hg in all core and auger samples
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CORE NO
2
7
9
25
served to provide both a more detailed record of Hg fluxes to Honda Bay during the past century, and also an independent corroboration of existing MGB analytical data through the re-analysis of duplicate materials at BGS, Keyworth.
LOCALITY
P.Princesa Bay
S. of Canon Island
Bacungan River Central H. Bay
Of the coring stations included in the BGS study, sites 7 and 9 were selected on account of their proximity to Sitio Honda Bay and the Tagburos estuary (ie. the major postulated sources of Hg contamination). Site 25, located c. 20 km offshore at a water depth of 43 m, was selected to provide an indication of bay-wide impacts. Site 2 was selected as a control site, as this Puerto Princesa Bay station receives sediment from unexploited cinnabar deposits located in the upper Inawayan catchment (Fig. 7). Lithological information for each core is given in Table 1.
LAT / LONG W.DEPTH
09'44.26N 23 m
Table 1: Core descriptions for BGS sampling stations in Honda Bay.
CORE LGH
4 m 118'42.89E I I 09'48.02N I 3 5 m I 0.4 m 118'48.16E
09'53.47N 118'46.11E 09'52.06N 43 m 118'55.71E
LOG. DESC.
Homogeneous olive grel silty clay. 0-24 cm: olive-grey silty clay with forams. 25-44 cm: dark olive- brown clay. Dark grey clay with forams. Sulphidic. 0-10 cm: silty clay with forams. 11-45 cm: olive grey silty clay with forams. 48-69 cm: olive grey clay. 70-400: grey-
5.1.2: Analytical procedures: A total of 56 core sub-samples of c. 4 g mass analysed for total and inorganic Hg analysis. All sub-samples were air-dried at low temperature (<40°C), disaggregated and ground to a fine powder using a milling procedure designed to minimise heat generation. An appropriate mass of sample (c. 1 g) was weighed into a 5Oml graduated test-tube and digested with cold aqua-regia under air-reflux for 24 hours. The tubes were then sealed (to avoid loss of volatile Hg) and heated to 140°C for two hours, cooled and diluted to volume.
All sediment sample digests were analysed by cold-vapour atomic fluorescence spectrophotometry (CVAFS), using an SP-Analytical Insts. Merlin AFS system. A conventional method of cold vapour generation was utilised, involving the reduction of Hg2+ to Hgo with stannous chloride, and argon stream transportation of the Hg vapour into the AFS detector. The practical detection limit for Hg (in solution) by this method is 10 ngll .
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Data for two mangrove mud samples from the mouth of the Tagburos River show a Hg concentration of 8 mgkg (PW 9 & 10). This value is substantially higher than recorded n offshore sediment, reflecting an ultrafine (clay-dominated) granulometry and high capacity for Hg adsorption.
The proportion of the total Hg load carried in -150 pm sediments and heavy mineral concentrates (HMC) varies significantly between the Tagburos River stations (PW4 & 5) and the gulley incised into the PQMI tailings pile (station PW 1). In the former, the concentration of Hg in the HMC is greater than that in the sediment by a factor of c. 2.5-7. In the latter, the HMC yields a lower Hg value than the sediment, suggesting that much of the Hg in the waste-pile is either ultra-fine cinnabar, or has been weathered from detrital sulphides and repartitioned into secondary phases. Downstream of the confluence, in the mid-reaches of the Tagburos River, this fine Hg-rich load does not significantly enrich the bottom sediment (e.g. at station PW5), but remains largely in suspension under the flow conditions prevailing. The deposition of this load in the very low energy environment of the estuarine mangroves is, however, likely, to contribute to the 8 mgkg Hg concentration recorded in this area.
Qualitative field observations of the flow regime of the Tagburos river suggest that the total sediment discharge (and hence the total Hg flux) from this system into Honda Bay is unlikely to be substantial. Compared to the larger Bacungan system to the north, the Tagburos river is small, sluggish and carries a bankful discharge of no more than 50 m3/S. The lower reaches (within 0.5 km of the coast) are also characterised by extensive marshy areas and mangroves, which act as an effective filter for suspended sediment.
5.3: Sitio Honda Bay mineralopical assessment.
5.3.1: Methodology: Previous chemical analyses of superficial waste from Sitio Honda Bay have indicated the presence of an average Hg concentration of 560 mgkg (Benoit et al., 1994). Such values have prompted speculation that the structure may be unsuitable for habitation, and re-settlement has been proposed for the c. 200 residents. To fully evaluate the risk, quantitative data regarding residential Hg exposure (including dust or vapour inhalation, hand-mouth ingestion or consumption of contaminated garden produce) are required for this population, with any additional exposure relating to occupational or dietary factors carefully differentiated.
Geochemical and mineralogical data indicating the concentration, speciation and bioavailability of Hg in mine tailings can provide a direct insight into the likely toxicological
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Size fraction >SO0 um
constituting c. 30% of total sample mass). Weight-percentage data for the tail and HMC components in each of the sub-500 pm fractions indicate that the HMC is only a small component of the solid assemblage (max. 7% total mass) throughout the analysed
Wt. of tail Wt of HMC 37.8 1 1.037
size range.
Hg in tail 280
Table 3: Concentration of mercury (mg/kg) in Sitio Honda Bay waste.
Hg in HMC % balance in tail 210 98
PW21 A I Mangrove mud to SW of jetty I 57 PW21 B I As above. I 48
320 210
The proportion of the Hg mass-balance held within heavy minerals was found to be generally small ( ~ 2 0 % ) in all analysed samples, indicating that cinnabar is of lesser importance than secondary alteration products as a carrier of Hg in the waste. Data for station PW6, however, suggest that the precise significance of the HMC varies significantly with both depth and grain size. In the surficial sample PW6- A, the coarse >SO0 and >250 pm fractions were found to hold ~ 4 % of total Hg in heavy minerals, rising to over 35% in the <20 pm fraction. Cinnabar within the waste must, therefore, be predominantly fine-grained and prone to rapid weathering.
220 96 3 10 79
Table 4: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay waste sample PW6A. All weight data are in grams. All concentration data are in mgkg. HMC = heavy mineral concentrate.
>63 pm >20 pm <20 pm EvaDorate
10.01 1.708 15.81 1.708 35.42 - 3.9 1 9 -
>250 um I 14.92 10.985 >120um 1 12.37 11.798
270 1 _U "ll 410 1360 800 e20 -
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>500 pm >250 pm >120 um
Table 5: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay waste sample PW6B. All weight data are in grams. All concentration data are in mgkg. HMC = heavy mineral concentrate.
29.32 0.998 80 60 98 14.57 0.697 80 80 96 9.724 0.58 1 80 90 94
>63 pm >20 pm c20 pm EvaDorate
5.405 0.426 80 30 97 23.02 0.625 150 80 99 15.33 - 3 10 - - 1.20 1 - <20 - -
% balance in tail Wt. of tail 28.57 9.417
Size fraction >500 pm >250 pm >120 pm >63 pm >20 pm c20 um
~
99 0.567 1.195 120 140 85
76 8.543 1.570
1.716 2.699 330 260
8.952 90 19.76
I I
8.652 Evaporate i 2.458
Table 6: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay waste sample PW6C. All weight data are in grams. All concentration data are in mgkg. HMC = heavy mineral concentrate.
% balance in tail 99 96 94 94 97
Evaporate I 1.300 I - I <20 I -
Table 7: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay waste sample PW6D. All weight data are in grams. All concentration data are in mgkg. HMC = heavy mineral concentrate.
Size fraction I wt. of tail I
Wt of HMC I Hg in tail I Hg in HMC I % balance in tail I I
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The datasets for more deeply buried samples, PW6-C and D show the HMC contribution to the Hg mass-balance to remain below 6% across the entire grain-size range. Any cinnabar originally present in waste forming these horizons must, therefore, have been comprehensively degraded and the Hg repartitioned into clays. The prevalence of maximum Hg concentrations of up to 550 mg/kg in the <20 pm (tail) components of PW6 B, C and D is consistent with this hypothesis.
Microprobe analysis of the <20 pm fraction of sample PW6 A was undertaken to establish the composition of secondary Hg compounds in the Sitio Honda Bay waste.This confirmed that the Hg in the clay-dominated assemblage is primarily held as an inorganic impurity in (or sorbed to) hydrous Fe oxide phases such as goethite and ferrihydrite.
In a previous study of Sitio Honda Bay waste and nearshore sediment geochemistry, Benoit et al. (1994) noted a decline in the proportion of total sediment Hg held in sulphide with increasing distance from Sitio Honda Bay, and proposed syn-dispersal dissolution and conversion to more labile (bioavailable) forms as a plausible cause. From the evidence now available regarding the presence of substantial concentrations of non-sulphide Hg within the jetty waste, these seaward adjustments to the Hg totaVHgS ratio could possibly be reinterpreted as a function of gravimetric sorting of cinnabar and secondary Hg carriers in the fine-silt and clay size range following the erosion of waste from the jetty by wave action. The role of methylation processes in the regulation the ratio can be specifically discounted, as both the Sitio Honda Bay waste and the marine sediments of Honda Bay hold Hg almost exclusively in inorganic phases.
5.4: Hvdrochemical survev;
5.4.1: Background: The potential for human Hg exposure through consumption of contaminated water in the Santa Lourdes area has received considerable attention, but existing datasets yield no consistent trend. The MGB have previously collected two suites of samples. Each included water from the PQMI open pit, samples from shallow tube wells immediately south of the PQMI site and surface water from Tagburos River. The first suite,
analysed at the MGB Quezon City laboratory, yielded no values in excess of 0.2 pg/l. The
second suite was submitted to SGS (Philippines) Inc. who reported concentrations an order
of magnitude higher, mostly in the range 2-4 pg/l. This discrepancy may reflect the fact that
both sample suites were unfiltered, and thus probably held variable suspended loads. In addition, the analysis of waters by CVAAS in both laboratories may have resulted in poor precision through operation close to the limit of detection.
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5.4.2: Sampling and analytical methods: Water samples were collected from four surface water localities, five boreholes and one thermal spring for full hydrochemical characterisation, total Hg and inorganic Hg analysis. Surface water sampling stations (see Fig. 9) included Tagburos River sites upstream and downstream of the PQMI mine, the PQMI open-pit and drainage water from the adjacent tailings pile. Boreholes, ranging in depth from 12 - 45 m, were primarily located in Santa Lourdes (proper), along the southern flank of the PQMI site (Fig. 9).
At each station, three 30 ml samples were filtered through a 0.45 pm Millipore cellulose
acetate membrane into Sterilin storage tubes. One was then stabilised with 0.6 ml
50%HN0,+50%K2Cr0, for total and inorganic Hg analysis, a second was acidified with 0.3 ml concentrated HNO, (Aristar) for major/trace cation analysis (by ICP-AES), and the third was retained unacidified for anion analysis (by ion chromatography). Field measurements of pH, Eh, conductivity and temperature were taken during sampling, using a series of Orion and Hanna Instruments meters and appropriate calibration standards.
Water samples for Hg analyis were split into equal aliquots for the independent determination of total and inorganic Hg. Total Hg analyses were conducted following pre- treatment of one aliquot with a brominating agent to oxidise all organo-mercury compounds to inorganic species. The difference between the Hg value recorded for this sub-sample and that for the corresponding non-brominated aliquot was assumed to constitute organo-Hg. For both aliquots, the oxidant preservative (K,CrO,) was reduced using a dilute solution of NH,.OH.HCl immediately prior to analysis. All determinations were made by CVAFS using the methodology described in section 5.1.2.
5.4.3: Results: Data showing the concentration of total Hg, plus all other hydrochemical parameters determined in the surface- and groundwater sample suite, are shown in Table 8 . Mercury was in all instances found to be present as >99% inorganic species, and accordingly organo-Hg data have not been presented. In all surface waters (PQMI mine pit and Tagburos River samples), Hg was present at concentrations below the CVAFS detection limit of 20 ng/l (O.ooOo2 mg/l). In the Santa Lourdes groundwater suite one value exceeding the 20 ng/l detection limit was recorded (40 ng/l at station PW 19), but can be considered to fall within the global background range. A Hg concentration of 140 ng/l was recorded in sulphidic spring water at station PW 15.
The basic hydrochemical signatures of all surface- and groundwater samples are summarised in Fig. 14, in which major cation, anion and TDS data are plotted on a Piper
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PW18-G 0.012 0.02 2.995 0.05 24.1 PW19-G 0.002 0.03 0.640 0.01 31.7 PW20-G 0.001 0.10 0.025 0.05 21.7
Table 8: Multi-element data for surface- and groundwater samples from the Santa Lourdes area. Suffixes indicate sample type: S = surface water; G = groundwater; H = hot spring . All element concentration data are given in mg/l. ND = NOT DETECTED.
ND 0.15 ND ND 0.02 ND 0.02 0.03 ND ND 0.52 ND 0.01
Sample P W 2 - s P W 3 - s P W 4 - s P W 5 - s PWlS-H PW16-G PW17-G PW18-G PW19-G PW20-G
H g pH <0.00002 4.57 <0.00002 7.96
0.00014 <0.00002
<0.00002 6.02
I
<0.00002 I 6.54
Eh (mV) Temp (C) Cond (US) 5 10 33 190 490 31 786 480 28 363 450 29 31 1 -295 80 6200 300 28 114 3 10 28 581 -50 31 506 260 30 664 3 10 31 794
Sample I H C 0 3 I C1 I SO4 1 NO3 I TOC I TIC I M g p w 2 - s I <20 10.62 121.2 I ~ 0 . 1 16.48 I 0.69 12.18 PW3-S I 72 142.4 1245.0 I 1.11 I 13.3 I 13.6 158.6
P W ~ - s 233 4.9 4.41 ~ 0 . 1 7.84 44.2 28.9 PWS-s 188 6.4 24.9 0.38 12.5 36.8 27.6 PW15-H 2570 779.0 5.11 42.0 10.8 489.0 15.4
I
PW16-G 35 14.1 545.0 ~ 1 . 0 10.5 I 7.63 93.7 PW17-G 210 37.4 29.9 CO.1 8.72 I 39.5 28.5
76.8 I 19.1 I 4.44
4 .4 4.8 1. 9
2 4
5.5: Marine fish survev:
5.5.1: Background: Following the preliminary DOH assessment of human blood Hg burdens in the Santa Lourdes-Tagburos area in 1995 (section 3.2), it was proposed that contamination by mining activities of Honda Bay fish stocks may account for the prevalence of elevated Hg levels in a small number of individuals who had neither worked at the PQMI mine, nor resided on or near any known mine-waste accumulation. This hypothesis was further strengthened by the preliminary conclusions placed on Hg data for fish and shellfish sampled by the EMB in November 1994 (see sections 3.2 and 3.3), showing drv weipht concentrations to range from c.005 mgkg for dalagang-bukid, to 10.96 mgkg for the predatory species, lapu lapu. For shellfish, dry weight concentrations for Perna viridis (mussel) were reported as 2.1 mgkg, while oyster concentrations of 36.9 mgkg were recorded. When compared uncorrected against the wet weight values for fish and shellfish at Minamata (0.4 -30.0 mgkg and 1.3 - 14.0 mgkg respectively), the Honda Bay concentrations appear high. However, when expressed on a wet weight basis, the values for all species sampled appear more moderate:- 1.78 mgkg for bisugo, <0.005 mgkg for dalagang bukid, 0.142 mgkg for galunggong, 2.00 mgkg for lapu lapu, 0.560 mgkg for matang baka and 0.684 mgkg for salay salay. A repeat survey of a similar species range in April 1995 yielded considerably lower Hg values, ranging from <0.0005 mgkg for danggit and salay salay to a maximum of 0.076 mgkg for lapu lapu (wet weight). It is notable that both EMB surveys were based on a single analysis for each species. Considerable inherent variability of Hg burden is likely to occur between individuals of all species studied, and this may provide the most plausible explanation for the contasting results obtained. In both surveys, the values presented for most elevated species are analogous to those reported as ‘normal’ for long-lived predatory fish worldwide (see Piotrowski and Inskip, 1981, for a comprehensive summary).
A subsequent study of fish Hg burdens in Honda Bay was conducted in 1995 by a research team from the University of the Philippines. Two sample suites were collected in independent trawls, and representative numbers of 9 species (with widely varying ecologies) analysed. The results showed only two species to carry mean burdens in excess of the US-EPA marketing threshold of 0.5 mgkg Hg. Highest concentrations (mean 0.924 mgkg) were found to prevail in a predatory species (talakitok), for which such values could be considered normal (Piotrowski and Inskip, 198 1).
5.5.2: Methodology: In the present study, 6 species of fish were collected with nets from both the inner and outer Honda Bay areas. The fish types taken are known only by local name: malakapas, salmonete, tuko, taba-taba, sap-sap and mackerel (confirmation of genus and species is awaited from the University of the Philippines). On the basis of morphology
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0
these species appear to reflect a broad spectrum of feeding guilds and trophic levels. Thus the fish groups sampled would record potential Hg exposure through the full range of detrital, algal and carnivorous food chain pathways.
Muscle samples from ten individuals of each species were dried at 50°C within 6 hr of collection (to facilitate transport to the UK without substantial decomposition) and the weight loss assessed in each case. All samples were subsequently digested in HNO,, diluted to an appropriate volume and analysed for Hg by CVAFS using the instrumentation described in section 5.1.2.
5.5.3: Results: Full analytical data (expressed as both dry weight and approximate wet weight) and summary statistics depicting the Hg burden of all fish samples are given in Table 9. The mean wet weight values reported for all species (0.09 - 0.33) are broadly consistent with those previously produced by University of the Philippines researchers. For the single species studied in both surveys (sap sap), the comparative wet weight mean values are 0.27 (UPI) and 0.31 (BGSBTE). Statistical analysis (ANOVA followed by Tukey HSD multiple comparisons) of the data on an inter-species basis indicates that sap- sap and mackerel have significantly elevated Hg concentrations relative to all other species. With respect to the mackerel, this distinction is entirely consistent with the high position of these species in the food chain. There is no statistically significant differentiation between than the remaining groups.
Table 9 (a-f) : Mercury burdens in Honda Bay fish (mg/kg).
2 6
0
0
0
0 0
e 0
0
0 0
0
0 0
0
0 0
0
0
0
0 0
0
0
0
0
0
0
0
Table 9 (cont.)
I I I
RANGE I Malakapas 10.05 - 0.42 10.25 - 2.10 I
0
0
0 0
0
0 2 7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0 0
0
0
0 0 0
0
0
0 0
0
0 0
0
0
0
0
0
0
Taba Taba Taba Taba Taba Taba Taba Taba
Table 9 (cont.)
0.05 0.24 0.07 0.32 0.09 0 .45 0.05 - 0.32 0.22 - 1.64
Sample no. 12.01 12.02 12.03 12.04 12.05 12.06 12.07 12.08
12.10 MEAN VALUE RANGE
2 8
0
0 0
0 0
0
0
0
0
0
0
0
0 0
0 0 0
0
0
0 0
0 0
0
0
0
0
0
0 0
0 0
0
0
Other non- Dredatorv
Table 9 (cont.)
Sample no.
14.01 14.02 14.03 14.04 14.05 14.06 14.07 14.08 14.09 14.10
MEAN VALUE RANGE
0.08 - 0.27 0.07 - 0.09 0.02 - 0.16 0.10 - 0.30 0.09 - 0.19
Mackerel
Dry weight Hg 3.21 1.31 1.19
1.32 2.41 0.90 1.87 1.41 2.53 1.70 0.87 - 3.21
Comparison of the wet weight Hg burdens in Honda Bay fish with threshold values for marketed fish in the USA (0.5 mgkg, US-EPA), and with global average data for species of varying ecologies (e.g. IRPTC, 1980; Table 10) indicates that the mean and, more significantly, the median levels prevailing in the Honda Bay samples are not exceptional. Separation and subsequent statistical analysis of data for individual specimens caught in the inner and outer sectors of Honda Bay yielded no significant differentiation. Realistically, all sampled species are extremely motile, hence significant differences across a continuous area of open water could not be expected.
Table 10: Approximate average wet-weight mercury levels (mg/kg) in muscle tissues of marine fish in major oceans worldwide.
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5.6: Mussel (Perm viridis) assessment
5.6.1: Mussel Hg assays: Bivalves are excellent indicators of heavy metal contamination, due to both their capacity to accumulate metals from their environment (mainly in particulate form), and their widespread distribution throughout the world. In many regions, bivalves also form an important source of human nutrition, and may therefore constitute a significant pathway for human metal exposure. On account of the biomagnification of metals which typically occurs during assimilation by shellfish, any small increase in ambient metal concentration resulting from pollution will typically be reflected by a distinct increase in mussel tissue concentrations.
During the BGS/ITE Honda Bay survey, samples of the species P e m viridis (green mussel) were collected from two locations. The first was situated in shallow water approximately 10 m off the southern margin of the Sitio Honda Bay jetty (near site PW 6, Fig. 13). The second was located close to the western shore of Canon island, approximately 6 km off the Tagburos - Sitio Honda Bay coast (see Fig. 7). All samples were returned to the haematology laboratory of Puerto Princesa Hospital for preparation and biomarker assessment within 8 hours of collection. All samples were purged in clean water prior to sub-sampling.
The soft tissues of 15 mussels from Sitio Honda Bay (coded PW6) and 10 from Canon Island (coded PW13) were air-dried at 50°C prior to transport to the UK for final weight determination and analysis. The dry tissues were partially digested in cold HNO, at ITE (Monks Wood) and forwarded to BGS for further reflux digestion and total Hg analysis by CVAFS.
5.6.2: Results: Dry weight and approximate wet weight Hg data for all mussel samples from Sitio Honda Bay and Canon Island are given in Table 11. The average wet weight value (2.13 mg/kg) and range (0.86 - 4.37 mgkg) established for the Sitio Honda Bay suite is almost an order of magnitude greater than that for Canon Island (mean 0.34 mgkg). The Sitio Honda Bay mean value falls within the lower quartile of the Minamata shellfish range (1.3 - 14.0 mgkg), indicating that mussels and analogous filter feeders from the immiediate vicinity of the jetty may be unfit for human consumption. The contamination of biota in this locality is entirely accordant with the high Hg concentrations observed in sediment from the same vicinity (see Benoit et al., 1994; or MGB survey data, September, 1995), and lateral concentration gradients for the two media are probably analogous. Accordingly, it is plausible that bivalve Hg tissue burdens decline to background within a few hundred metres of the Sitio Honda Bay source. The & Hg concentrations recorded in P e m viridis from the Canon Island station is within the
3 0
a 0
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a 0
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0 a 0
0
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e 0
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0 e 0
0
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0 0
0
Sample
PW13-1 PW13-2 PW13-3 PW13-4 PW13-5
international background range for shellfish, signifying that bivalves from the wider Honda Bay may be suitable for human consumption.
Wet wt Dry wt Hg Sample Wet wt Hg Dy wt Hg
Hg 0.45 2.28 PW13-6 0.24 1.22 0.29 1.45 PW13-7 0.36 1.84 0.24 1.24 PW13-8 0.27 1.36 0.58 2.92 PW13-9 0.41 2.08 0.26 1.30 PW3-10 0.31 1.57
Table ll(a): Dry weight and approximate wet weight mercury concentrations (mg/kg) in tissues from Honda Bay mussel samples (Perna v i r id i s ) .
Table ll(b): Mercury concentrations (mgkg) in Honda Bay mussel samples (cont).
5.6.3: Neutral-red biomrker assessment. An ecotoxicological field test based on the neutral-red retention (NRR) capacity of invertebrate cells has been successfully utilised to assess metal-induced stress in a number of marine and terrestrial settings (e.g. Weeks and Williams, 1995). In the present study, haemolymph (0.02-0.05 ml) was extracted from 25 mussel specimens from sites PW6 and PW13, and mixed with an equal volume of temperature-adjusted physiological ringer using a 1 ml hypodermic syringe. Each haemolymph suspension was transferred then to a siliconized Eppendorf (0.5 ml) for subsequent (NRR) analysis,
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A neutral-red stock solution, comprising 20 mg of neutral-red dye dissolved in 1 ml of dimethyl sulphoxide, was freshly prepared. Subsequently, 10 pl of the stock solution was diluted with 2.5 ml of physiological ringer, giving a working concentration of 80 pg/ml. To avoid crystallization of the neutral-red dye, the working solution was renewed every hour during the measurement process. Haemolymph samples of 20 ~1 were placed on a microscope slide, and the cells allowed to adhere to the slide surface for 3 minutes before the application of the neutral-red working solution (20 pl) and a cover-slip.
Each slide was continuously scanned at random (by rapid haphazardous repositioning) under a microscope (at constant magnification) to observe any temporal adjustments to the condition of the cells. Each visualization was divided into 3 minute intervals, from which the numbers of cells with fully stained and unstained cytosol were determined. Observation was stopped at the interval when the ratio of stainedunstained cytosol was greater than 50% of the total number of cells counted. The midpoint of the interval was noted as the NRR time.
5.6.4: Results: A statistically significant difference (P<O.OOl) was observed (based on a Student’s t-test two sample analysis, assuming unequal variances) between the NRR times determined for mussels from the Sitio Honda Bay and Canon Island locations. The former had an average NRR-time of 15 min (+3.0), while latter consistently displayed at retention of e. 45 min (f4.0). These trends are consistent with an increased level of toxicological stress and attendant cell dysfunction in the Sitio Honda Bay sample population. While alternative causes of stress (eg. between-site temperature, salinity or organic pollutant variations) have not been specifically discounted, the close correlation between NRR times and Hg tissue burdens at the two sample sites is most likely to be causal.
5.7: Assessment of human HP bu rdens:
5.7.1: Background The extent to which the populations of Santa Lourdes and Sitio Honda Bay are exposed to Hg through residence on, or near, a mine waste substrate can be inferred from bioavailability data derived from mineralogical studies of Hg speciation in the waste material (section 5.3). Such studies, must, however, be supplemented by direct monitoring of the potentially impacted populations (alongside one or more appropriate control groups) to produce a comprehensive risk assessment. Hair analysis is internationally recognised as suitable for this purpose (e.g. WHO, 1981). The method holds advantages over blood Hg analysis as it is non-invasive, and results are not prone to short-term dietary influences. Hair Hg burdens are a direct function of average blood
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concentration (section 5.7.4 below) and can thus be used to make crehble inferences regarding blood burdens.
5.7.2: Methodology: An electoral list was acquired of individuals living in three selected sampling areas:- (i) Sitio Honda Bay (a community living on a mine-waste substrate), (ii) Santa Lourdes proper (a community living at the margin of the PQMI site) and (iii) Tagburos (a coastal fishing community 1 km south of Sitio Honda Bay). Hair samples were collected from the rear of the scalp (Fig. 15) from representive sub-groups totalling 35% of the Sitio Honda Bay population and smaller components of the Tagburos and Santa Lourdes (proper) communities. Data regarding age, sex, profession (including prior involvement with mining), body weight and residence history were collated by interview, with the assistance of officials from Puerto Princesa hospital (see Appendix 1).
Following the completion of the survey, all Palawan subjects were classified into five groups: (i) Sitio Honda Bay residents, (ii) Tagburos residents , (iii) Santa Lourdes residents living adjacent to the PQMI site, (iv) other residents of Santa Lourdes (mainly living west of the PQMI site), (v) ex-mineworkers from PQMI. A small control population from Manila was also sampled for comparative purposes. Of the four ex-miners identified, it is notable that two had previously been classified as having elevated blood Hg burdens (c. 25 ng/ml) in the 1995 DOH survey, and had subsequently been 'detoxified at the Puerto Princesa hospital. The age range and total number of individuals in each sample group is shown in Figure 16.
Hair samples of approximately 2 g mass were prepared for analysis by washing repeatedly in distilled water to remove dust and other surficial contaminants. They were then air-dried, cut into 1 cm lengths using nylon scissors, weighed and transferred to 50ml graduated test- tubes. Ten mg of V,O, and 5 ml of HNO, was added to each tube, and the samples were left under air-reflux overnight. The following morning all samples were heated to 140°C for 5 minutes, cooled and 2 ml of H,SO, added. After a further heating period of 15 minutes, all solid material was digested and the solutions were cooled and diluted to an appropriate volume. An aliquot of each solution was used to determine total Hg content by CVAFS.
Certified hair standards obtained from the EC (0.36 mgkg) and the Republic of China (12.3 mgkg) were digested in the fashion outlined above and analysed in conjunction with the Palawan sample suite to ensure data accuracy. The Hg values obtained from 8 independent analyses of the EC reference standard were in the range 0.32 - The corresponding range for 7 independent analyses of the Chinese standard
3 3
0.34 mgkg. was 10.06 -
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transformation data indicate that approximately 20% of subjects hold blood Hg burdens in excess of 20 ng/ml. This trend is closely accordant with that previously derived from direct blood Hg analysis of 42 subjects from Santa Lourdes and Tagburos by the DOH in 1995, indicating an 25% exceedance of a this threshold.
5.7.5: Influence of dietary vs. residential Hg exposure: Derivation of the relative importance of dietary, occupational and residential contributions to total Hg exposure is critical for the accurate assessment (and, if necessary, amelioration) of toxicological risk. From the data presented in this study, there is no evidence to suggest that residential factors significantly influence the Hg body burdens of any Palawan population groups. In particular, any exposure of the Sitio Honda Bay population as a consequence of their residence on a mine-waste substrate can be considered negligible, given the statistical comparability of hair Hg burdens for this group with those determined for the adjacent coastal barangay of Tagburos. The limited significance of mining activities or mine waste deposits on present-dav human Hg exposure is equally evident with respect to the Santa Lourdes community living adjacent to the PQMI site, for which a mean hair Hg burden substantially lower than that of the Tagburos coastal community has been derived. These trends are, in turn, consistent with the mineralogical data for mine waste presented in section 5.3, indicating that Hg in mine waste at the Sitio Honda Bay site is both predominantly inorganic, and held in species with extremely low bioavailability . Viewed in conjunction, the mineralogical and human body burden data currently available suggest that there is no immediate requirement to re-locate the Sitio Honda Bay population (or to otherwise modify the structure) on grounds of Hg exposure limitation.
In contrast to the strictly limited influence of residential factors, there is strong evidence that diet exerts a first order control on Hg exposure within the Palawan population. The predominance of fish as a source of methyl Hg in the human diet has been recognised for several decades (WHO, 1976), to the extent that up to 90% of spatial variations of Hg burdens worldwide are explicable by reference to fish consumption (Piotrowski and Inskip, 198 1). This reflects the intense biomagnification of Hg in aquatic foodchains, often producing enrichment factors of >30,000 in top-carnivores (shark, barracuda etc.) relative to ambient water Hg concentrations. While the global average Hg concentration in hair is of the order of 2 mgkg (blood equivalent - 8 ng/ml), the ‘normal’ blood levels for high fish consuming populations (including Italy, southern France, indigenous Canadian or American Indians) can range from 20-80 ng/ml (e.g. Paccagnella and Prati, 1974; Riodolfi, 1977; Clarkson, 1975; Health and Welfare of Canada, 1979).
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The WHO has provided guidelines for estimating likely hair Hg burdens in populations with varying levels of (non-contaminated) fish consumption. These are:- consumption once monthly = 1.4 mgkg, once weekly = 2.5 mgkg, and once daily = 11.6 mgkg. Interviews with participants in the Palawan survey indicated that fish consumption is generally of a daily frequency. Of the 130 subjects included in the Palawan survey, 128 displayed hair concentrations falling below the anticipated daily consumption threshold of 11.6 mgkg. The inferred body burdens of virtually all subjects can be thus be considered a predictable and direct function of diet.
The temporal fluctuations of Hg body burden evident in one ex-mineworker sampled during the hair survey are particularly significant with respect to the influence of dietary vs. occupational factors. The subject concerned was detoxified at the Puerto Princesa hospital in 1995 following the determination of a blood Hg concentration of 25 ng/ml during the DOH survey. On treatment this level is likely to have fallen substantially, but has since risen once again to >20 ng/ml (inferred from a scalp-interface hair concentration of 5.3 mgkg). This rapid post-treatment elevation of blood Hg concentration is fully consistent with a dietary burden, with equilibrium re-established rapidly following departure from hospital. This does not, in itself, raise doubt over the diagnosis of clinical symptoms in the subject, as these are likely to be manifestations of historical (occupational) exposure of a much greater magnitude.
5.7.6: Toxicological implications of the recorded Hg burdens: There is no international consensus regarding the practical ‘risk’ threshold for methyl Hg in humans. The precise blood concentration beyond clinical damage occurs (often following a long latent period) is dependent on a complexity of factors including age, exposure duration and nutrient status (with respect to elements such as Se). In practice, it is therefore unlikely that any single value will prove universally applicable. Despite these uncertainties, evidence from clinical and epidemiological studies undertaken worldwide suggests that the 20 ng/ml ‘action level’ currently proposed by the DOH (for use in the identification of subjects for remedial treatment) is unusually low. Such an ultra-cautious approach may have severe cost-benefit implications for subsequent treatment programmes, as a large percentage of the total population will be encompassed. As noted previously (section 5.7.5), the proposed 20 ndml threshold falls within the ‘normal’ blood concentration range for sizeable populations in Europe and North America (e.g. Paccagnella and Prati, 1974; Riodolfi, 1977; Clarkson, 1975; Health and Welfare of Canada, 1979), with no toxicological effects observed.
Any revised blood Hg threshold or action value for use in Palawan should ideally be based on local- and/or regional-scale dose-response datasets. In the absence of such data, the guidelines provided in the WHO Health Criteria Document (1976), subsequently revised
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under the UNEP GEMS and MARC programmes (1981), may be of value. The latter incorporates dose-response data from over 300 studies conducted in Iraq, Japan, Canada, USA and southern Europe. It concludes that an increased risk of mild non-specific neurological damage may result from life-long exposure beyond a blood Hg threshold of 80 ng/ml. Assuming shorter exposure, risk is generally apparent beyond a higher threshold of 200 ng/ml. Pregnant women constitute a special case, for whom a threshold of <100 ng/ml may be more appropriate. In a 1996 Science of the Total Environment Special Volume on mercury pollution in Latin America, a risk threshold of 50 mg/kg in hair (blood equivalent = 200 ng/ml) is routinely utilised.
While the determination of a toxic threshold is important with regard to the isolation of individuals or groups at risk, it is equally critical that amelioration strategies fully account for the Hg exposure pathways involved. Detoxification procedures (typically involving the use of a sulphydryl receptor) are potentially applicable for the treatment of acute exposure. To be fully successful, however, clinical treatment must be coupled with subsequent removal of the subject from the contaminant source. The approach is thus inherently suited to the treatment of occupational rather than dietary exposure, and is unlikely to provide a long-term mechanism for reducing the imact of dietary Hg exposure in the coastal communities of Palawan. In the literature review undertaken as a component of this study, no instance has been recorded in which clinical detoxification has been proposed, or applied, for the treatment of individuals/populations exposed via fish consumption. A more common amelioration strategy under such circumstances involves progressive modification of the diet (notably methods of fish preparation) through community education. Programmes of this type have been successfully deployed among native American Indian populations in Canada and the USA.
6: SUMMARY AND CONCLUSIONS.
From the evidence available, the declarations by the Philippine media in September 1995 regarding the occurrence of a major mercury poisoning episode on Palawan cannot be substantiated. On the basis of the data presented in this study, the following conclusions can be drawn:-
1: The Sitio Honda Bay jetty exerts a marked localised influence on sediment quality. The datasets of Kapuan (1982), Benoit et al. (1994) and the MGB/BGS (1995) are accordant in noting sedimentary Hg concentrations in excess of 100 mgkg within 100 m of the structure. The concentration gradients around the jetty are, however, relatively steep, and Hg values decline to background within a distance of 400-800 m.
4 1
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2: Sediment Hg concentration data acquired by the MGB and BGS for the wider Honda Bay environment highlight no evidence of contamination. The average interfacial Hg
concentration in Honda Bay sediments (c. 40 pgkg) lies within the global background
range. Downcore Hg profiles indicate no significant adjustment of Hg influx during the past c. 100 years. Outwith the strictly limited zone noted above, the impact of mining andor coastal tailings disposal can be considered negligible.
3: Data produced by the MGB and BGS for waste material from the Sitio Honda Bay structure indicate that the total Hg content is variable, with values ranging from 30-340 mgkg. The down-profile distribution of Hg is characterised by a systematic decline of concentration with depth. There is unsubstantiated evidence that garden topsoil imported onto the Sitio Honda Bay jetty (with a relatively high organic content) may actively accumulate Hg to levels exceeding those of the underlying waste.
4: The speciation or geochemical form of Hg in the Sitio Honda Bay waste (and in the Hg- enriched sediments adjacent to the structure) is overwhelmingly dominated by inormnic Hg-phases. Onshore and nearshore methylation rates for Hg appear low. Cinnabar is not the sole inorganic host, as c. 90% of the total Hg present resides in fine particulates of low
specific-gravity. Microprobe analyses of the <20 pm fraction of one Sitio Honda Bay
waste sample have shown a substantial proportion of this non-sulphide Hg to occur in ferric oxyhydroxide complexes which, in turn, are strongly bound to clay mineral surfaces. The bioavailability of Hg (and other heavy metals) in this form is extremely limited.
5: Analysis by CVAFS of filtered (0.45 pm) surface- and groundwater samples from the
Tagburos-Santa Lourdes area (including the PQMI site) has indicated no detectable Hg contamination. All aquifer and stream water samples yielded Hg values of 40 ng/l or below, and thus fall within the global background range. Such low concentrations are surprising given the highly mineralised, geothermally active setting involved. The
sporadically elevated Hg values (up to 4 pg/l) reported for Santa Lourdes groundwaters in
certain previous studies (notably the dataset supplied to the MGB by SGS Laboratories) are of doubtful credibility due to the sampling and analytical procedures involved.
6: The Hg burdens of 60 fish samples (10 each of six species) from the inner and outer sectors of Honda Bay fall within the ranges typically encountered for comparable species worldwide. The mean Hg burdens for all species fall below the US-EPA marketing threshold of 0.5 mgkg. No recorded value approaches the Minamata range. The values recorded show accordance with data acquired for Honda Bay fish by EMB and University of
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the Philippines researchers. All depict low or moderate Hg burdens when expressed on a common (ie. wet weight) basis. To date, no evidence has been provided to justify any bay- wide restriction of fishing activities (or fish consumption).
7: Samples of Pernu viridis (green mussel) recovered from a site 10 m off the Sitio Honda Bay jetty exhibit Hg enhancement in soft tissues to levels within the Minamata range (max. 21 mg/kg dry weight). Attendant toxicological stress has been inferred from a low NRR capacity in individual cells from these samples. Comparative analyses of Perm viridis specimens from Canon Island (5-6 km offshore) showed tissue Hg burdens to lie exclusively within the global background range (1-2 mg/kg dry weight). Ecotoxicological tests for this population produced no evidence of cell dysfunction. These trends concur with sediment-based evidence (1 & 2 above) indicating the strictly localised impact of the jetty structure on the marine environment.
8: A comprehensive survey of Hg body burdens in 130 Honda Bay subjects based on hair analysis has highlighted a universally high level of Hg exposure relative to a small control population from Manila. It is, however, extremely unlikely that this exposure level is reflective of geological factors or mining activities. Statistical comparison of the Sitio Honda Bay, Tagburos and Santa Lourdes (proper) populations failed to significantly discriminate the former two groups, from which it can be concluded that the Sitio Honda Bay population is not subject to elevated Hg exposure as a consequence of residence on the Hg-enriched substrate. Population resettlement on health grounds is therefore probably unwarranted. Estimated mean blood Hg values for the five Palawan sample groups range from 8.8-17.6 ng/ml, with a maximum individual value of 74.1 ng/ml. The mean and median values for all groups are typical of populations consuming fish at a daily frequency. No alternative mechanism of exposure need be invoked. Data regarding the precise blood Hg threshold associated with the onset of toxicological risk are equivocal. There is, however, virtually no evidence of appreciable risk at blood concentrations of e80 ng/ml, irrespective of exposure duration.
9: Strategies for ameliorating Hg-induced health hazards must take account of both the clinical symptoms presented and the mechanism of exposure involved. In cases of acute Hg exposure from a residential or occupational source (for example, through former employment in a mine), post-exposure detoxification may be beneficial. The approach has strictly limited applicability, however, in instances of dietary exposure, for which a strategy of progressive food supply modification is routinely adopted.
10: The above conclusions are substantially based on a single field sampling programme, conducted in December 1995. This short survey constitutes no adequate substitute for longer
4 3
term monitoring, which will inevitably provide the key to a more comprehensive understanding of the sources, environmental behaviour and toxicity of Hg in Honda Bay and beyond.
7: ACKNOWLEDGEMENTS
This study was funded by the UK ODA through the diversion of resources from Engineering Division Technology Development and Research (TDR) programme R6226 (Mitigation of Mining-Related Mercury Pollution Hazards). Logistic support and field guidance was provided by staff of the Philippines Department of Environment and Natural Resources (Mines and Geosciences Bureau) and the Puerto Princesa Hospital, Palawan. University of the Philippines researchers Ms. Grace Doming0 and Mr Mike Reyes participated enthusiastically in all aspects of the field programme. Discussions with Dr G.S. Jacinto (University of the Philippines) and Dr A. Socrates (Provincial Health Officer, Palawan) were invaluable throughout both the design and execution phases of the survey.
8: REFERENCES:
Benoit, G., Schwantes, J.M., Jacinto, G.S. and Goud-Collins, M.R. 1994: Preliminary study of the redistribution and transformation of HgS from cinnabar mine tailings deposited in Honda Bay, Palawan, Philippines. Marine Pollution Bull. 12,754-759.
Clarkson T.W. 1975: Exposure to methyl Hg in Grassy Narrows and White Dog reserves. Interim-report., US-EPA.
Health and Welfare of Canada. 1979: Task force on organic mercury in the environment. Grassy Narrows and White Dog reserves, Ontario. Dept. National Health and Welfare, Ottowa, Canada.
Kapuan, A.F., Kapuan, P.A., Tan, E.C. and Vercelez, F. 1982: Total mercury in water and sediments from the Honda Bay area in Palawan, Phil. J. Sci. 3, 135-144.
Kershaw, T.G., Clarkson, T.W. and Dhahir, P.H. 1980: The relationship between blood levels and dose of methylmercury in man. Arch. Environ. Health, 35,28-36.
Krauskopf, K.B. 1979: Introduction to Geochemistry. McGraw Hill, 617 pp.
Paccagnella, B., Prati, L. and Bigoni, A. 1973: Studio epidemiologico sur mercurio nei pesci e la salute unama in un isola Italiana del Metiterraneo. Ig. Mod. 66,479-503.
4 4
0
0 0
0
0
0
e 0
0
0
0 0
0
0
a 0
0
0
0 0
0
0 0 a 0
0 e a 0
0
0
0
Paccagnella, B. and Pratti, L: 1974: Total mercury in blood and hair of Italian people. Ig. Mod. 67, 369-30.
Piotrowski, J.K. and Inskip, M.J. 1981: Health effects of methylmercury. MARC, University of London. 82 pp.
Riodolfi. M. 1977: Further epidemiological study of Hg levels in fish and human blood and hair. Ig. Mod. 70, 169-186.
United Nations Development Programme: 1986: Geology of Central Palawan, Technical Report no. 6, DP/UN/PHI-79-004-6. UNDP, New Uork, 56 pp.
Weeks, J. and Williams, T.M: 1995: A simple ecotoxicological field test to determine mining-related heavy toxic trace element stress. Ecotoxicology-(in press).
World Health Organisation 1976: Environmental Health Criteria Document 1 : Mercury. WHO, Geneva.
World Health Organisation 198 1 : Revised Health Criteria Document: Mercury, WHO, Geneva.
4 5
0
e 0
0 0
0
a 0 0 0
0
0 0 0
0 0 0
a 0
0
0
0
0
0
0
a a 0
0
0
0
0
0 0
APPENDIX 1: Descriptive information for all subjects of Manila and Palawan groups from
whom hair samples were collected for Hg analysis. Note that the code JP is utilised in place of SHB to depict the Sitio Honda Bay group.
4 6
S I T 1 0 HOflDA B A Y
C H I L D R E H C O D E J r
f l l 3 U E S E X
1 R d r i a n D e l a C r u r n Z L a a r n i B o j o s F
3 J c r r l c E r c o b a n c z n f J n y b n l d o C a p a c h o n
S n a r l a n o K a t h i r i n e R l F
6 n a r i a n o K r i r t c n c R l l F
7 D a u i d X r i s t i n c
B U n i c o 6 i r l i c
fiDULT C O D E
9 E l c n a h g u i l a r
l e ~ o g e i i o U l l l a n u e u a
1 1 K z i h i l l n V i l i h n u c v a
lZ 6 i n a F c U i l l a n u c u a
1 3 R a n d y V i 1 l a n u c u a
1 4 ~ n n a l f z a n a y o l i n o
1S f i l f r t d a K a g o l i n o
1 6 H i c o l a s A l a r o
1 7 s i r n A l n r o
1 8 J u d i t h A l n r o
1 9 L o l i t a R e y c r
2 8 P c d r o G r a p a n
Z l A r s e n i a R c q u i n t o
Z Z L o c t l y n D a n a o
2 3 F r c d D a n a o
Zt F o r d i u t s D a n n o
2 5 4 n g e l i t a G c j o n
2 6 T i t o G c j o n
27 B l o r i a C o r t e r
Z R V i c t o r i o H o r c n o
2 9 J o c p n n U n i c o
3 0 J o c e l y n U n i c o
3 1 U a l e n t f n a U n i c o
3 2 J o s i c B u n g a r
33 F e l l n a U a l l r d o r
3 4 J u l l t o 6 o n n a l r r
35 R y a n U u l l a g
36 J a y h p o l i n a r
37 R o l a n d o H a r a p a o
38 E r l l n d a n a r a p a o
3 9 F c r n a n d a f i p o l i n a r
i i i i i a r i t c s i i c i a C r u z
1 1 R n i t a D t l a C r u z
- - . - .. .
F
F
J P
F
n F
F
tl
F
n n €
F
F
K
€
F
n tl
F
n F
n n F
F
F
P
n n n n F
rr t
P
-
R 6 E
7
6
7
7
6
b
6
2
5 7
5 1
3 4
17
15
2 4
6 7
O C C U P A T I o n U T . K B . h D D R E S S
S i t i o H o n d a B a g )
S I t i o H o n d a B a y
S i t i o H o n d a B a y
S i t i o H o n d n B a y
S i t i o H o n d h B a g
S i t i a H o n d a B a y
Sitio H o n d a B a y
S i t i o H o n d a B a y
S t o r e O u n c r 5 8 . 8 S i t i o H o n d a R a y
F i s h e r m a n 19.0 S i t 1 0 H o n d a B a y
H o u s c k c c p c r 5 2 . B S i t i o H o n d a B a y
H o u r c k c c p c r S B . 0 S i t i o H o n d a Hay
F i f h r r u a n 5 2 . 0 S i t i o H o n d a R a y
H o u s e k e e p e r 5 0 . B S i t f o H o n d a B a y
F i s h e r m a n 5 5 . 0 S i t i o H o n d a B a y
2 5
2 7
4 8
Z B
7 t
3 1
10 m o s
2
2 5
2 6
5 3
5 R
3
29
5 s 2 5
53
12
7
2 1
3 6
3 1
Z t o r r O u n c r
S t o r e O u n e r
H o u s r k e e p c r
f i s h c r n r a n
H o u s r k c c p c r
H o u s e k e e p e r
66 F a r a c r / K i n c U o r k 7 8 . 0 S i t i o H o n d a B a y
H o u s c k t c p c r
F i nlitrnan
S t o r e O u n e r
F i s h t r n a n
S t o r e O u n e r
H o u s c k c c p c r
H o u s r k c c p c r
S t o r e O u n t r
f i s h c r m a n
f l r h c r a a n
H o u n e k e e p r r
*3.8 S i t i o
38.6 S i t i o
4 6 . 9 S i t j o
5 1 . 5 S i t i o
33.2 S i t i o
5 4 . 5 Sftio
18.0 S i t i o
1 3 . 8 S i t i o
l B . 9 S i t l o
s4.5 S i t i o
6 8 . 8 S f t i o
5 i i . R S i t i o
12.5 S i t i o
50.0 S i t i o
5 1 . 8 S i t i o
4 9 . 8 S i t i o
58.0 Sit10
18.0 Sitio
16.6 Sitio
* 6 . 0 S i t i o
b 0 . B S i t i o
5 1 . 5 S l t i o
H o n d n
n o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
2 2 P u m p B o a t O p e r n t 56.8 S i t i o H o n d a B a y
i i S t u d e n t 45.6 S i i l o ~ o n d a B a y
5 B . B S i t l o H o n d a B a y 58 H o u r c k c e p t r
.. . . - . .
0
n i z n a r l o n D a g a n t a
0 13 J o h n l J n i c o n n i i f l l c h a c l n a n a l o
0 i 5 B c n J i e Q u i u a r
4 6 f i b n c r Q u l u a r
n n
1 7 D i o n i t o G o n r a l e r n + 0 n a r i s s a H c r r c r a F
5 3 R l d r l n f i s t a c a a n n 5 8 J e f f c r r o n O t r a r a n n
5 1 J a m e s f i r c h i c O t s a r a n n 0
S Z C h r i s t o p h c r C a ~ ~ a c h o H 5 3 f i l b e r t h l u t a y a F
0 5 1 E l y B c r a m c n
2 4
1 6
9
8
1 2
b
1 8
1 1
1 2
9
1 3
1 0
1 0
F i s h e r r a n
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
5 5 n a r i t e s H e r r c r a F 1 2 S t u d e n t
5 6 K r i s t i n a n a n a b a t F 1 2 S t u d e n t
0 5 7 n a r i a l e n B c r a r c F 9 S t u d e n t
5 8 S h e e n a A f c a t a a n F 1 0 S t u d e n t
F - l e D a y C a r e U o r k c r 0
I 0 1 E l f r a b c t h P u l a n c o
1 8 2 F c d c r i c o T u ~ n o g n 8 5 f a r r e r / S k i n L e s s
o n L e g s
O S A t t T R L G U R D E S
I C h r i s t i a n A l o n s a g a y n 0 Z E r u i n J a m a n d r c n
~i R o s a l i e A l o n s n y a y F
0 4 e l l a n ~ l l o n s a g a y n
5 S a 1 u a d o r A n a n o n 0 6 n a r i c c l D u c o r i n F
0 7 E ~ i l y n C e l e d o n i o F
8 R u s s c l l P a l a c s K
0 9 K a t r i n a h i o n s a g a y F
1 0 J a k c D o r r c r o n 0 1 1 n a r y J a n c S i n o y F
0 0 1 4 J c s r a n f I l o n s a g a y F
0 18 P i a n o n i s
0 1 9 T e r e r a f I m a n o F
0 ~ i i i u i y j a g i i a s n a r i n a s
1 2 B e n j i c B o q u c n a n 13 G l c n d a B o q u e n a F
1 5 D o n n a D o r r e r o F
1 6 ~ e c e i y n ~ a c o s a F 1 7 B l e n d c l C a s u p a n a n F
F
2 8 C a t h e r i n c B o n t o g o n F -
2 2 R u b y l y n F u c g o 0
F
9
a 1 1
12
1 1
12
12
8
1 2
1 2
1 1
1 2
1 0
1 1
14
1 1
9
9
8
1 1
i i 1 1
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S i t u d e n t
S t u d e n t
S 0 . B S l t i o
5 5 . 0 S i t i o
3 6 . 0 S f t l O
2 5 . 8 S i t t o
3 0 . 0 S i t 1 0
16.6 S i t i O
2 5 . t 3 i t i o
2 7 . 0 3 l t i o
3 3 . 8 S i t i o
2 5 . 9 S i t i o
3 7 . 0 S f t i o
2 2 . 0 S i t i o
2 5 . 0 S i t t o
3 0 . 0 S i t i o
3 S . 0 S i t i o
21.0 S l t i o
z1.0 S i t i o
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
7 2 . e H a i n i t
5 5 . 0 H a i n i t
2 3 . 6 S t a L o u r d c s
2 7 . 8 S t a L o u r d r s
2 s - 3 S t a L o u r d e r
2 3 . 6 S t a L o u r d c s
2 7 . 7 S t a L o u r d c s
3 3 . 0 S t a L o u r d e s
2 5 . 8 S t a L o u r d e r
S t a L o u r d c s 2 2 . e 2 7 . 0 S t a L o u r d c s
3 0 . 0 S t a L o u r d c r
2 2 . ? S t a L o u r d e s
S t a L o u r d c s
2 5 . e S t a L o u r d c s
2 6 - 0 S t a L o u r d e s
4 0 . 0 S t a L o u r d e s
2 6 . 0 S t a L o u r d e s
t a . 6 S t a L o u r d c s
1 9 . s S t a L o u r d e s
20.9 S t a L o u r d e s
3 3 . 6 S t a L o u r d e s
4 3 . 6 S t a L o u r d r s
S t a L o u r d e s 3 0 . 0
2 a - 0
0
0
~ , H * L O U R D E S ( C o n ? C O D E S L * 0 2 , R o s a F e L a n t r c l l a F 1 1
0 2 7 C h e r y l H l c g a r t- 1 2
0 2 9 R o b c r t o 6 a b r i c l n 1 2
F 1 3 z 3 ~ p r l ~ y n ~ a c o s a
Z S n a r l c c l n c j o l l o F 1 3
R c z c l E a r l a s F 1 2
28 J r f f r c y L a u c r o n i l l a K 1 2
38 ti i n o D a s n a r 1 n a s n 1 3
F 5 0
S t u d c n t
S t u d e n t
S t u d c n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
2 0 . 6
2 8 . 6
3 0 . 0
3 2 . 7
5 3 . 6
4 0 . 0
2 5 . 8
3 0 . 0
5 6 . 0
S t a L o u r d c s
S t a L o u r d c s
S t a L o u r d c r
S t a L o u r d c r
C c n t r o
n a t a h i m ik
n a t a h ie ik
C c n t r o
C c n t r o
S T A L O U R D E S n f 3 T h H I t l I K ( N E A R H I H E ) . C O D E S L n
n Z n e l u l n D a n a r o n 3 H a r c o L a g p a n n 4 6 c r a l d L a n g o r a y a n n
6 S u s a n T a y l o r F
5 J o b c r I y L a u r o n l l l a n
7 J o b e r l y L a n g o r a y a n F
8 n a r y firm S c r a l d c F a 9 J o h n n n u r i c c U h n y n
0 S E D a n i e l T a y l o r n
. i t b C U R O S - S I T 1 0 A P L A Y R
C O D E T G
1 0
1 8
1 8
1 1
1 0
1 0
Y
3
S Z
S Z
S t u d c n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d c n t
S t u d e n t
2 5 . 0
2 5 . 0
2 4 . 0
2 6 . 0
2 7 . e 2 3 . 0
2 s . 0
2 3 . 0
2 0 . 0
31.0
n a t a h i n t k
n a t a h ia I k
n a t a h i m i k
R a t a h i s ~ i k
n a t a h i a i k
n a t a h i n i k
t l a t a l ~ l n ik
H a t a h I n i k
n a t a h la 1 k
n n t a h i m i k
1 D n n t c G a l l c g o
0 2 A r i c l G u h c l d c
3 R c r e l T a m p o n
4 J o c g G a l l c g o 0
5 R a n i 1 J U n n n
0 7 T c o f e i a G a i i c g o F
6 J e n u e G a l l e g o F
8 E l c o t c r i o S e u a s i o n n
l e F l o r e n c i a P a l o r o P
1 1 C r i s t i n a S u r d i l l a F 0 1 2 C o n c c p c i o n S u r d i l l a P
1 3 n a r i a n c B c n t i r o s o F
14 n i c a B e n t i r o s o F
Z B F i s h c r n a n
2 8 F l r h c r a a n
18 F i r h c r n a n
1 8 F i s h e r m a n
16 F I s h c r e a n
z 4 s H o u s e k e e p e r
67 f i r h e r m a n
6
* 0 H a u s e k e e p e r
5
3 2 H a u s c k c c p c r
1
2
2 5
st, H o u s c k c c p c r
5 S t u d c n t
6 1 . 0
6 5 - 8
s s . a 6 8 . 8
6 0 - 0
5 . 9
S 0 . B
6 0 - 6
16 . B
4 8 . e 1 7 . 0
s a .e 9 . 0
1 2 - 0
5 0 . 0
5 0 - 0
2 8 : 0
T ~ g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o r
T ~ g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o r
T a g b u r o s
T a g b u r o s
T a g b U r o r
L e n g t h
S t a y
S / B
S / B
8 y r s .
S / B
7 y r s .
S / B
S / B
1 0 y r s
S / B
8 y r r .
S / B
1 6 y r s
6 1 0 s .
6 m o p .
6 m o p .
1 0 y r s
3 / B
0
0 0
0
0
e 0 0
e 0
0 0
0
0
0
0
e 0
0
0 0
0
0 e 0
a 0
0
0
0 0 0
Name
TG (cont) 18 Vicente Lapis 19 Pedro Lapi s 20 Feliza Rolano 21 Petra Lapis 22 Ambrosia Maratas 23 EmmaDopeno 24 Ma. April Luna 25 Crisanta Oruta
EX 1 Federico Mumar 2 Federico Vejana 3 Unknown 4 AidoMedina
CON 1 Shirlina Oreas 2 James Oreas 3 Bettina Gonzales 4 Jocelyn Domingo 5 Michelle Domingo 6 Nelsie Garcellan 7 RamonSingh
Sex
M M F F M F F F
M M M M
F M F F F F M
Age Occupation Wt
56 46 28 55 55 9 8 48
65 70 70 65
36 4 12 34 3 19 36
fisherman fisherman housekeeper housekeeper fisherman student student housekeeper
ex-miner ex - mi n e r ex-miner ex-miner
dentist - - housewife -
mechanic
52 59 45 46 60 18 17 43
- - - -
- 25 30 65 20 40 65
Residence Period
Tagburos Tagburos Tagburos Tagburos Tagburos Tagburos Tagburos Tagburos
(detoxified) (detoxified) (wheelchair) -
Manila Manila Manila Manila Manila Manila Manila
12 yrs 11 yrs 8 yrs 10 yrs 15 yrs 4 yrs 2 yrs 9 yrs
0
0
a 0 0
a 0 a 0
0
0
0 0
e 0
0 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
I,
APPENDIX 2: Total Hg concentration data for all subjects included in the Palawan hair survey. Note that the code JP is utilised in place of SHB to depict the Sitio Honda Bay
group.
4 7
O A G G LAB NO. 8942
4
JP 12 ~ 0.1024 5.68 6.04 JP13 1 0.1023 6.1 6 JP 14 0.1 398 3.77 JP 15 0.1 01 6 6.55 JP 16 0.1022 2.78 JP17 I 0.1373 0.40
~
SAMPLE , WEIGHT] PPM repeat value JP 1 ' 0.1110 1.39 JP 2 0.1 059 2.40 JP 3 1 0.0721 4.34 i
JP27 j 0.1057 JP28 ~ 0.1118
IJP 4 i 0.1015 I 6.69 I
3.61 1 8.32
IJP 5 j 0.1047 1 3.28 I 1
JP32 ~ 0.1159 JP33 1 0.1174
IJP 6 1 0.1092 ~ 3.56 1 1
2.1 4 3.14 1
IJP 7 ~ 0.1444 1 6.77 1 1
JP 35 JP 36
IJP 8 ~ 0.0903 1 2.49 1 1
0.1 209 ~ 6.53 0.1150 i 7.55
IJP 9 ~ 0.0547 ~ 1.07 1 1
JP 39 1 0.1286 2.38 JP40 j 0.1047 1.16
IJP 10 ! 0.1124 1 10.93 1 1
~~
IJP 11 1 0.1128 1 3.78 1 1
JP 41 0.1201
JP 43 1 0.1243 ~ ~ 4 2 i 0.1040
JP44 1 0.0119
1.64 3.97 2.87
<0.10
lJP18 j 0.1157 I 0.72 1 1 2.65
JP20 1 0.1164 ~ 10.28 IJP 21 1 0.1007 1 2.35 I 1 IJP 22 0.1042 1 2.00 1 1 IJP 23 1 0.0692 1 3.01 1 1 IJP24 i 0.1017 1 2.77 1 1 IJP25 ~ 0.1102 ~ 3.36 1 1 1JP26 I 0.1259 1 10.02 1 1
IJP38 1 0.1131 1 4.04 1 1
AGG LAB NO. 8942
JP 52 0.1 01 2 18.54 JP 53 0.1 287 6.92 JP 54 0.1102 , 7.45
SAMPLE 1 WEIGHT/ PPM 1 repeat value JP 45 0.0461 1 4.18 i
JP 56 JP 57
i
JP46 ! 0.0878 1 6.09 1
0.1 250 ' 4.91 0.1 073 5.67
JP 47 1 0.0146 1 3.83 1
JP 102 1 0.0506 - I
I
JP 48 1 0.1072 1 3.24 1
2.88
JP49 i 0.1063 1 1.67 1 JP50 1 0.1152 1 16.58 1
JP 55 1 0.1135 I 3.70 1
I I
JP 101 1 0.1028 1 2.35
SAMPLE ! WEIGHT^ PPM i 1 GSH-1 1 0.10041 0.32 ,
GSH-1 ~ 0.101OI 0.32 I GSH-1 j 0.1OOOI 0.34 I GSH-1 I 0.1006/ 0.32 ~
GSH-1 ~ 0.09981 0.32 I GSH-1 I 0.101OI 0.32 I GSH-1 ~ 0.09951 0.34 1
e AGG LAB NO. 8942
e e 0 e 0 0
e e 0 0 0 e 0 0 0
0 I,
0
0 0 0 0 0
0 0 0 0
0 0 I)
0
SL 2 1 0.1020 SL 3 i 0.1072
SAMPLE I WEIGHT i PPM I reDeat value I
3.1 7 1.46
CON 1 i 0.0506 1 1.07 1 i
SL 4 SL 5
CON2 ~ 0.0737 1 0.70 1 1
0.1051 ~ 1.78 0.1463 1 0.98
CON 3 I 0.1280 1 0.49 1 1
SL 6 1 0.1528 S L 7 j 0.1030
CON 4 i 0.1005 1 0.37 1 1
3.83 2.98
CON 5 j 0.1010 1 0.33 CON 6 1 0.1073 I 0.98
S L 21 SL 22 SL 23
CON 7 ~ 0.1094 1 0.48 1 1
0.1 502 1.69 0.1 003 1.50 0.1 554 2.97
I I !
EX 1 I 0.1264 1 5.29 EX 2 1 0.1089 1 5.31 1 5.94 1 EX 3 1 0.1170 1 1.05 I 1 EX 4 I 0.1115 1 1.51 1 1
SL 1 I 0.1091 1 1.31 1 1
S L 8 i 0.1143 1 1.76 1 1 SL 9 ~ 0.1224 1 1.28 1 1
I
SL 10 1 0.1148 j 3.62 SL 11 1 0.1363 1 3.95 SL12 I 0.1232 1 3.45 I
SL 14 1 0.1643 1 1.91 1 1 SL15 i 0.1215 1 3.92 1 1 SL16 I 0.1094 1 3.34 1 1 SL17 ~ 0.1128 1 1.44 1 1 SL18 I 0.1012 ~ 1.06 1 1 sL19 i 0.1142 I 1.22 I 1 SL20 I 0.1096 1 2.09 I 1
SL 24 0.1 223 0.1 008
SL 26 0.1 124 SL 27 0.1261 1 0.92 SL28 1 0.1579 1 2.10 1 1 SL29 1 0.0665 1 3.25 1 1 3L30 ~ 0.1162 1 2.46 1 1 3L31 ~ 0.1048 1 2.09 1 2.68 1
0 0 AGG LAB NO. 8942
TG 11 TG 12
0 0 0 0 0 0 a a 0
0 0 0 0
0 0 0
e 0 0 0 0 0 0 0 0 0 0 rn rn
D
0.1140 j 3.58 ~
0.1138 4.58 j
SLM 2 0.0759 1 2.30 ~
TG 13 TG 14 TG 15
SLM4 1 0.0922 I 2.93 I 1
0.1232 1 0.72 I 0.1180 1 0.78 ~
0.1445 j 1.86 ~
SLM5 1 0.1159 I 2.27 ~ 1
TG 17 TG 18
SLM 6 I 0.1097 1 2.46 I 1
0.0782 ~ 2.91 ~
0.1113 1 5.74 ~
SLM7 I 0.1445 1 1.83 1 1
SLM 10 0.1 336 3.54
TG 1 I 0.1199 1 2.08 1 1 TG 2 1 0.0593 1 5.97 1 1 TG 3 1 0.1171 1 5.52 1 1 TG 4 I 0.0386 I 1.87 i 1 TG 5 1 0.1084 1 3.25 1 1 TG 6 I 0.1040 1 8.00 1 1 TG 7 1 0.1142 I 5.58 1 1 TG 8 1 0.1291 1 7.25 1 1 TG 9 1 0.1054 1 5.08 1 1 TG10 1 0.1170 1 3.02 1 1
1 1 TG16 1 0.1104 1 2.87 ~
11.12
TG 21 0.1 322 TG 22 I 0.1209 5.51 TG23 I 0.1356 1 1.92 1 1 TG 24 1 0.1094 I 1.91 i 1 TG 25 I 0.1239 1 4.63 1 1
