JosetteWeirOAG Toxicity of the arsenic-based pesticide Monosodium Methane Arsenate (MSM

8/7/2019 JosetteWeirOAG Toxicity of the arsenic-based pesticide Monosodium Methane Arsenate (MSM

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G Toxicity of the arsenic-based pesticide Monosodium Methane Arsenate (MSMA)

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nvironmental Petitions

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Proactive Disclosure

Toxicity of the arsenic-based pesticide Monosodium

Methane Arsenate (MSMA)

etition: No. 97

ssue(s): Human health/environmental health, pesticides, and toxic substances

etitioner(s): Canadian Association of Physicians for the Environment (CAPE)

Date Received: 5 November 2003

tatus: Completed

ummary: In this petition, the Canadian Association of Physicians for the Environment (CAPE) expresses concernbout the arsenic-based pesticide MSMA, which is used by the forestry industry to control bark beetle. The petitionsserts that there are new scientific findings on the toxicity of arsenic that need to be considered by the Pest

Management Regulatory Agency of Health Canada. Several questions are posed in this petition about MSMA,

ncluding questions on re-registration, environmental effects, and human exposure.

ederal Departments Responsible for Reply:Health Canada

Petition

Attachment

Office of the Auditor General and the Commissioner of Environment and Sustainable Development

40 Sparks St.

Ottawa, OntarioK1A 0G6

Attention: Petitions

Aug 25, 2003

We are submitting a petition under the Auditor General Act, to the Hon. Anne McLellan, Minister of Health, asollows.

rom: The Canadian Association of Physicians for the Environment (CAPE)
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PETITION

Context

ince July 13, 2001, Dr. Josette Wier, a pediatrician originally trained in France and a member of the CanadianAssociation of Physicians for the Environment (CAPE), has repeatedly brought to the attention of the PesticideManagement Regulatory Agency (PMRA) her concerns about an application for a permit to use the arsenical pesticMSMA (Monosodium Methane Arsenate). The BC Ministry of Forests (Morice Forest District) was the applicant fhe use of 3,300 kg of arsenic (active ingredient, in the form of MSMA) over a three-year period to "control" bark

eetle. Dr. Wier has specifically pointed out that research from the last 3-5 years shows that the assumptions uponwhich the safety of the product was established no longer hold. This is based on general research and especially onxtensive communications from Dr. W.R. Cullen, professor of chemistry at UBC and a world authority on arsenicoxicity. She has repeatedly encouraged the PMRA to get in touch with Dr. Cullen and has forwarded to the PMRAopies of relevant documentation and research materials.

o date, the PMRA has initiated only a single short phone call to Dr. Cullen, of no particular relevance. Furthermon a letter to Dr. Wier, dated July 18, 2001 and signed by Mr. Richard Aucoin, Acting Chief Registrar, the agency htated that an internal review of the data from Drs. Wier and Cullen "had concluded that although the findings areotentially important, these findings are not substantially new in the context of our existing knowledge of arsenic".his statement is in complete contradiction to Dr. Cullen's testimony at the Environmental Appeal Board (EAB)earing held in Smithers, BC, June 17-21, 2002, where Dr. Wier was the Appellant. His critique of the PMRA letteent a week before (June 11, 2002) to the lawyer representing the BC Ministry of Forests, went unchallenged at theearing. It became very clear that the PMRA had an outdated view of the metabolism of arsenic.

hortly after the EAB hearing, on July 4, 2002, CAPE informed the PMRA of Dr. Cullen's points. We received, onAugust 23, 2002, a response from Ms. Wendy Sexsmith of the PMRA, which was in essence a rearranged copy of une 11, 2002 letter which had been so thoroughly discredited by Dr. Cullen at the hearing. The PMRA, despite clend very disturbing new data from an unimpeachable source, resolutely maintained the position that NO newnformation was relevant.

We wrote the PMRA again on September 19, 2002, detailing very precise questions to be answered. Ms. Sexsmith'eply, of November 13, reiterated the inaccurate and completely invalidated notion that "total" arsenic is the relevan

ndicator, commenting, with surprising and probably unintentional irony, that there is so much of it in the Canadiannvironment that one should not worry about the effects of adding more! While acknowledging that there has been

monitoring whatsoever of exposure in applicators, and that there is and will be no effort made to monitor smallmammal or insect exposure even though such creatures form the basis of the food chain, she nevertheless concludewithout any cited evidence) that "there will be no contamination of dietary or water resources" after MSMApplication.

We asked Dr. Cullen to review Ms. Sexsmith's response of November 13, 2002. His evaluation, which is attached this petition, is at marked variance to that of the PMRA.

We then asked to meet with the Hon. Anne McLellan, Minister of Health, in a letter dated March 14, 2003. Weeceived no response. After five unanswered phone calls over a period of one month to her office, [name withheld]nformed Dr. Wier that [name withheld], had decided that CAPE should meet instead with Dr. Claire Franklin, headhe PMRA, with whom we had not previously interacted. A teleconference was duly held with Dr. Franklin on May003 but generated the same response as all previous interactions. Dr. Franklin made it crystal clear that she had nontention of altering or modifying the PMRA's position that MSMA was safe to use.

We then again requested a meeting with the Honourable Anne McLellan in an e-mail to [name withheld] of June 1003. We pointed out to [name withheld] that we wished to settle this issue before July when injections were toesume. Out of fifteen subsequent phone calls to [name withheld], thirteen were completely ignored. One resulted ixchange with [name withheld], who said she would pass it on to [name withheld], and as a result of the final one, uly 24, Ms.Wier was informed that [name withheld] had decided that we should not meet with the Minister and thetter would be forwarded (time unspecified) informing us of the reasons.


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his letter has now arrived; it simply endorses the position taken by the PMRA, without explanation.

rom this background, several issues emerge:

1. The difficulty obtaining a response from the Hon. Minister's office to repeated requests for a meeting with tMinister, and obtaining any sort of substantive response to our concerns or to the evidence presented to her.

2. The PMRA's unshakeable position that MSMA is safe, despite solid contradictory evidence from one of themost respected Canadian scientific authorities on arsenic toxicity.

3. The utter opacity of the process for handling requests for interaction with the Minister and with the PMRA.

The following are the questions we seek to have answered:

1. At what point does a persistent inquiry from a concerned and well-informed citizen on an issue withsignificant health implications generate a substantive response from the Minister's office?

2. Does the Minister routinely, and without independent analysis, endorse the PMRA's position that newscientific findings do not challenge the safety of a currently registered pesticide? If not, how is an independeanalysis triggered?

3. We understand that a request for re-registration of a pesticide must come from the Minister. Are there anyother ways of triggering a re-registration process, and are any of those available to the public at large?

4. In this particular case, in which the PMRA's position that MSMA is safe has been flatly contradicted by oneof the most respected Canadian scientific authorities on this matter, what process or mechanism is in place tdeal with such an outright divergence of opinions? Is the PMRA always presumed to be correct, in the face any other scientific authority?

5. Dr. Franklin wrote that the PMRA was not legally obliged to consider testimony provided in a provincialpermit appeal. Is the PMRA in fact not obliged to concern itself with Dr. Cullen's rebuttal of their position,simply because it took place in a provincial court and under oath? Is this a general principle?

6. Again with reference to this particular case, has MMA III ever been measured in applicators that the Ministor the PMRA is aware of?


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7. Regarding the new scientific findings on the metabolism of arsenic, the PMRA states that "although thefindings are potentially important, these findings are not substantially new in the context of our existingknowledge of arsenic". Which specific new scientific findings is the PMRA choosing to dismiss? How dothese findings not change our understanding of arsenic toxicity? In other words, what is the exact thresholdwhich new findings about the toxicity of a substance become significant, and how and by whom is itdetermined?

8. When was MSMA registered and when was it re-assessed? For which uses is MSMA currently registered? Iforestry use a minor use registration? What exactly is a minor use registration?

9. What actual evidence does the PMRA possess indicating that the measurement of total arsenic is sufficient tmonitor the effects of MSMA?

10. What measurements are employed by the PMRA, or its delegate, to assess the movement in ecosystems ofarsenic derived from applications of MSMA?

11. What are the effects of MSMA on small mammals, cavity-nesting birds including woodpeckers, or insects,including honey bees?

12. What are the risks of arsenic exposure and subsequent toxicity arising from a forest fire involving MSMA-treated trees, to both forest firefighters and adjacent communities? What are the relevant arsenic-containingcombustion products from the burning of an MSMA-treated tree and what is their toxicity?

13. What is the potential exposure of a logger cutting, say, 100 treated trees in a day, and breathing smoke fromthe incineration of their branches? If a logger becomes ill from absorbing toxic levels of arsenic, what systeis in place for estimating his or her exposure, monitoring its source, and providing prompt and effectivetreatment?

14. Have public health officials been warned of possible dangers associated with either work-related or forest firelated exposures to MSMA-treated wood?

15. When is re-registration of MSMA scheduled by the US EPA? If such re-registration is being scheduled earlthan originally planned, does this not imply increasing evidence of hazards associated with this product? Ifsuch urgency is warranted in the U.S., of what relevance is the precautionary principle to the PMRA while are-assessment is being conducted?

16. If MSMA fails to be re-registered in the US, how long will it take for PMRA to respond to this decision, anwhat would that response likely be?


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These conclusions are based on the following:

1. Studies at the US EPA and at the University of Arizona beginning in the mid 1990s have revealed thatmethylarsenic(III) species are cytotoxic in a range of cell lines, some human, and are more toxic thaninorganic arsenic species, often by factors of a thousand or more.

2. Studies at the US EPA beginning in the late 1990s have shown that methylarsenic(III) species are genotoxiin some cell lines. The corresponding arsenic(V) derivatives have little or no activity.

3. The methylation of arsenic in mammals, including humans follows the path:As(V) ' As(III) ' MeAs(V) ' MeAs(III) ' Me2As(V) ' Me2As(III)

and it was widely held that this was a detoxification process because the methylarsenic(V) species, in boldare not very toxic in animal models and these are the species excreted in urine. However, these are thespecies that were detected by the commonly used analytical method that was incapable of finding otherarsenic species. It is now known that the methylarsenic(III) species, in italics, that are an integral part of thmethylation pathway, are present in human urine. They are found to be the major species present in the uriof individuals, e.g. in Mexico, exposed to high levels of arsenic in their drinking water.

4. It has been known that dimethylarsinic acid, cacodylic acid, is a likely human carcinogen and it is nowbecoming apparent that the mode of action involves the formation of methylarsenic(III) species, probably tMe2As(III) in the scheme above.

5. MSMA, an arsenic(V) compound, has been regarded by regulators as a potential source of the likely humancarcinogen dimethylarsinic acid, but this was underplayed by regulators. However, if this is accepted then tsame metabolic process would proceed through the formation of the much more toxic methylarsenic(III)species not all of which would be further methylated.

Response to the Response to the letter from Dr Warren Bell

With reference to Attachment 1

Level of MMA(III) in forest litter.

suggest that the author actually read the quoted references, particularly Cullen and Reimer.

here is a vast difference between MSMA on the ground or elsewhere and other arsenic species. The backgroundrsenic level is of no concern here. Think of MSMA as a totally different species that has to be evaluated separatel

f all arsenic species were the same and additions contributed only a little to the background environmental burdenwould still be dealing with calcium arsenate as an agrochemical.

As for methylarsine, it could be formed in an anaerobic environment, flooded soil for example, but I don't think thassue has been raised. What is under discussion is that the MSMA could be reduced to species such as methylarsenxide, MeAsO (which is probably MeAs(OH)2) in dilute solution), in the soil or elsewhere. These methylarsenic(II


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pecies are cytotoxic and genotoxic. See comments on the current US EPA position.

Monitoring Dataensitive techniques for monitoring arsenic in urine have been available long before 2001. In fact a study done in 1

s quoted at the end of the paragraph. Most of the material in this paragraph is plain obfuscation. Monitoring can beone if necessary. See comments on the current US EPA position.

Norris article.Again the main issue is being avoided. Monitoring has not been done, and to say that it was not done because it wa

ssumed that the results would be acceptable is hardly a justification. Prudence alone should suggest that workersandling a toxic compound should be monitored.

mall Mammals' exposuream assuming that again the reference to methylarsine is an error as it was in the first paragraph. Some of the studiuoted are old and were made at a time when it would have been difficult to obtain speciation. In fact I doubt theuthors would have considered such an enterprise. Total arsenic values are not much use as an indicator of exposurpecific arsenic species. The situation is much different now and there is no excuse for the lack of useful information, for example, the arsenic species and their concentration in specific organs such as liver, if that is a concern.

Contamination of dietary, water resources, and plants (sic?)Here again this response shows a complete lack of appreciation of the problem. MSMA is not arsenic. The referencre lamentably out of date and irrelevant. For the record quite a lot is known about the arsenic species in mushroomnd there is very little of it which is the same "arsenic" that is in the ground.

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Minister's Response: Health Canada

9 March 2004

Dr. Warren BellCanadian Association of Physicians for the Environment

01-130 Spadina Avenueoronto, Ontario

M3V 2L4

Dear Dr. Bell:

urther to my acknowledgement letter of December 10, 2003, and in accordance with the requirements of section 2he Auditor General Act, I am pleased to provide you with Health Canada's response to the questions raised in your

etition concerning the safety assessment of the arsenical pesticide Monosodium Methane Arsenate.

hank you for your interest in this matter and I trust this information will prove helpful.

incerely,

Original signed by Pierre S. Pettigrew, Minister of Health, Minister of Intergovernmental Affairs and Minister

esponsible for Official Languages]

ierre S. Pettigrew


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NTRODUCTION

Health Canada has been requested by the Office of the Auditor General to respond to a series of questions innvironmental Petition no. 97 as they pertain to the mandate and responsibility of Health Canada. Health Canada'sest Management Regulatory Agency (PMRA) was identified to provide the Petitioner and Office of the Auditor

General with detailed responses to the questions and concerns raised in Environmental Petition no. 97.

HEALTH CANADA RESPONSES

Health Canada has reviewed Environmental Petition no. 97 and developed detailed responses to the 17 questions pon the petition. The questions and their associated responses are provided below.

Question 1: At what point does a persistent inquiry from a concerned and well-informed citizen on an issue

with significant health implications generate a substantive response from the Minister's office?

Response 1:

n striving to improve the health of all of Canada's people, while respecting individual choices and circumstances, t

Minister of Health has always maintained and will continue to maintain an open and transparent office for Canadiao voice their concerns. Accordingly, all inquires, whether to the Minister or the Department, are taken seriously anre responded to in as substantive a manner as possible.

Question 2: Does the Minister routinely, and without independent analysis, endorse the PMRA's position thnew scientific findings do not challenge the safety of a currently registered pesticide? If not, how

an independent analysis triggered?

Response 2:

he Pest Management Regulatory Agency (PMRA) has been mandated by the Minister of Health to administer theest Control Products Act(PCPA)and to exercise sound scientific judgment. The officials who are employed to caut that mandate have the scientific expertise to exercise such judgment and provide the Minister with sound advic

which he can and does rely.

With respect to triggering a re-evaluation or a special review of an existing product in light of new scientific findinlease refer to Response 3 on the following page.

Question 3: We understand that a request for re-registration of a pesticide must come from the Minister. Athere any other ways of triggering a re-registration process, and are any of those available to th

public at large?

Response 3:

he PMRA's re-evaluation program is described in Regulatory Directive 2001-03. The purpose of the program is tossess the continued acceptability of older, registered pesticides to human health and the environment. Monosodium

methane arsenate is one of the 401 actives registered prior to 1995 that are being re-evaluated. The Re-evaluationrogram consists of four distinct (sub) programs. Program 1 includes active ingredients and their end-use products

which a Risk Assessment Document or Reregistration Eligibility Decision (RED) document has been published byUnited States Environmental Protection Agency (EPA). These review documents must be of such quality to allow


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Canadian regulatory decision to be made without substantial in-house work. Program 2 includes products that requetailed in-house re-evaluation before a regulatory decision can be made. Program 3 is focussed on pest controlroducts that are scheduled for a new type of reassessment in the US under the Food Quality Protection Act(FQPArogram 4 is a program of targeted re-evaluations (Special Review or SR) and involves reviews that are triggered boncerns arising from adverse effects reports as well as products where national or international commitment orolicies require the PMRA to address a specific aspect of health or environmental safety.

As mentioned in Regulatory Directive 2001-03, opportunity is limited for public input into priority setting for produeviewed under Programs 1 and 3 as these priorities are driven by the availability of US review documents (Program

nd 3). A pesticide review under Program 2 or 4 may be triggered by concerns from the public provided that thevidence being presented is new and has scientific merit.

n the case of MSMA, the PMRA considered and included all information on the speciation of arsenic, including thew information provided by Dr. Cullen, in the Agency's risk assessment. This new information did not change theutcome of the risk assessment (i.e., even when speciation and the higher toxicity of certain species is considered, tsks remain acceptable). Accordingly, a special review was not triggered for this product. However, as indicated in

Response 15, MSMA is currently under re-evaluation by both the PMRA and the US EPA.

n the future, the new Pest Control Products Act, which was given Royal Assent in December 2002 but has not yetome into force, allows for further stakeholder input into priority setting for re-evaluations. Section 17 of the new P

Control Products Actstates that any person may request a special review of the registration of a pest control produy making a request to the Minister. The Minister initiates a special review if the supporting documents accompanyhe request provide reasonable grounds for the Minister to believe that the health or environmental risks are, or itsalue is, unacceptable.

Question 4: In this particular case, in which the PMRA's position that MSMA is safe has been flatlycontradicted by one of the most respected Canadian scientific authorities on this matter, what

process or mechanism is in place to deal with such an outright divergence of opinions? Is thePMRA always presumed to be correct, in the face of any other scientific authority?

Response 4:

he PMRA's position is that when considering the restricted use detailed in the provincial permit, which includes thevel of training and the type of protective equipment required for applicators, together with the fact that the speciforestry use of MSMA is a targeted spot application (direct injection into individual trees in infrequent "spots" in thorest), applicator, bystander and environmental exposure should be minimal and, therefore, would not result innacceptable risk.

t is important to understand that the toxicity (or hazard profile) of a chemical does not by itself, determine risk. It ihe amount, duration and route of exposure to the chemical that must also be considered. In the case of MSMA use

Canada, this use is both localized and restricted to individual trees. Together with the additional precautions imposehe exposure potential and risk to human health and the environment are minimized.

he PMRA recognizes and does not dispute Dr. Cullen's research findings regarding the potential hazards of arseniHowever, as indicated above, hazard is but one component of risk assessment. When the exposure profile for this u

f MSMA is factored into the risk assessment, the risks for properly protected workers do not exceed the level ofoncern.

Question 5: Dr. Franklin wrote that the PMRA was not legally obliged to consider testimony provided in aprovincial permit appeal. Is the PMRA in fact not obliged to concern itself with Dr. Cullen's

rebuttal of their position, simply because it took place in a provincial court and under oath? Is


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a general principle?

Response 5:

t is the PMRA's understanding that this question relates to an explanation which Dr. Franklin provided in a letterated June 5, 2003 to Dr. Warren Bell as detailed below. That explanation was in response to certain statements may Dr. Bell in a letter of May 15, 2003 to Dr. Franklin concerning a conversation they had on May 6th. The statemelated to information that had been entered in evidence at an Environmental Appeal Board hearing.

n the response dated June 5, 2003, Dr. Franklin indicated that, "...although PMRA was not legally obliged to consiestimony provided in a provincial permit appeal, [the PMRA] had reviewed the document to consider the testimonnd arguments put forth by Dr. Cullen and any other information [that] might be relevant to our risk assessment of

MSMA." Dr. Franklin also noted that the PMRA had, on a number of occasions, indicated that the work of Dr. Cullthough important, does not necessitate a change in the PMRA's conclusions with respect to the acceptability of thsks posed by MSMA. It was further noted that the risks posed by this use of MSMA under a provincial permit remcceptable and that the PMRA had previously supplied Dr. Wier with detailed information on why, based on thenformation available, the use of this product poses minimal risk to humans or the environment, including wildlife.

Dr. Franklin's explanation was intended to convey the message that the Agency is not obligated to act on informatiimply because it was provided as evidence in a legal proceeding. It is the relevance of the information to the carryut of the statutory responsibilities which determines whether and how it should be relied upon. When consideringull response provided by Dr. Franklin, (indicated above), it is apparent that the suggestion made in Question 5 (i.e.hat the PMRA did not "concern itself with Dr. Cullen's rebuttal of their position") does not properly reflect Dr.ranklin's explanation.

Question 6: Again with reference to this particular case, has MMA III ever been measured in applicators ththe Minister or the PMRA is aware of?

Response 6:

Regarding the availability of monitoring data on urinary levels of MMA (III) in applicators, it should be noted thatlthough the methodologies for arsenic speciation have evolved over the years, it is only within the last few years thensitive techniques for the speciation of arsenic methylation intermediates have been developed and published (Le001). Also, certified reference material has yet to be established for all arsenic species.

iological monitoring studies are sometimes used as part of the risk assessment process for occupational exposure.While it might be of interest to conduct appropriate biomonitoring and / or bioindicator studies, including speciationalysis, on urine samples from MSMA applicators, how these data should be applied to a science-based riskssessment would then need to be considered. An article by Norris (1985) provided total arsenic measurements frompot urine samples of MSMA and cacodylic acid applicators that had been collected in the 1970s. The worker scenn the Norris report (tree-thinning) involved the treatment of a much larger number of trees, which is a higher expocenario for applicators when compared to applicator treatment of infrequent "spots" for bark beetle control in BC.

While the data suggested some level of arsenic exposure, the PMRA agreed with the author's premise that with proandling techniques and the use of protective gear, applicator exposure levels would be minimised. To our knowledo other applicator bio-monitoring studies relevant to the forestry use of MSMA have been conducted to date.

Question 7: Regarding the new scientific findings on the metabolism of arsenic, the PMRA states that

"although the findings are potentially important, these findings are not substantially new in thecontext of our existing knowledge of arsenic". Which specific new scientific findings is the PMRchoosing to dismiss? How do these findings not change our understanding of arsenic toxicity? In


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other words, what is the exact threshold at which new findings about the toxicity of a substancebecome significant, and how and by whom is it determined?

Response 7:

he PMRA has not dismissed any new scientific findings. It is important to recognize that the carcinogenic potentiMSMA in humans remains uncertain and is still being investigated and debated by various scientific experts. Forxample, a recent report indicated that MMAA did not cause cancer in rats or mice that were exposed to MMAA in

heir diet for 2 years (Arnold et al., 2003).That being said, the statement referred to in Question 7 regarding theexisting knowledge of arsenic" was based on the knowledge that inorganic arsenic is a known human carcinogen hat from the regulatory perspective, using conservative assumptions, the possibility that MSMA couldbe carcinog

was considered when assessing the risk. Once again it is important to keep in mind that the toxicity (including potearcinogenicity) of a chemical does not by itself, determine risk. It is the amount, duration and route of exposure tohemical that must also be considered.

Question 8: When was MSMA registered and when was it re-assessed? For which uses is MSMA currently

registered? Is forestry use a minor use registration? What exactly is a minor use registration?

Response 8:

he MSMA product was first registered for bark beetle control in 1970. This has been re-examined on previousccasions as proposals for expansion of use or research permits were being considered. Nothing at that time suggesn unacceptable risk with the existing use.

Conifer thinning and bark beetle control are the only registered uses of MSMA in Canada. In addition to these usesMSMA is currently registered in the U.S. for many other uses, such as on turf, cotton, sugar cane and citrus groves

Minor Use Registration. Projected sales of some pest control products in Canada may be so low that manufacturersonclude they cannot justify the costs to support Canadian registrations. Therefore, for commercial reasons, such

roducts may not be available for use in this country. Many of these products are regarded as essential to cost-ffective pest control, and to the competitiveness and sustainability of agriculture, forestry, aquaculture and otherectors. These products are often referred to as "minor use products". Submissions for registration for these types oroducts typically occurs via sponsor groups, and more recently Agriculture and Agri-Food Canada has taken on thole of developing the needed data and submitting for registration of these minor use pesticides.

Note, however, the application for registration of the specified MSMA product in forestry was submitted by theegistrant United Agri Products, not through the user requested minor use label expansion program.

Question 9: What actual evidence does the PMRA possess indicating that the measurement of total arsenic i

sufficient to monitor the effects of MSMA?

Response 9:

t is not clear whether the petitioner is referring to measurement of arsenic in environmental media or humans. Aiscussion on each of these issues is provided below.

rom an environmental perspective, the distribution and speciation of arsenic in MSMA-treated trees and the targerganism have already been investigated (Maclauchlan et al. 1988a, 1988b; Manville et al. 1988; Newton 1986).

MSMA-treated trees contain inorganic arsenic (arsenate plus arsenite), monomethylarsonic acid (MMAA) andacodylic acid (DMAA). Untreated trees also contain these arsenic species, but at lower concentrations. The


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oncentrations and species of arsenic in the target organism (bark beetle) are also being investigated in a current stonducted by Environment Canada, in consultation with the PMRA.

or monitoring arsenic concentrations in soil, the concentration of "total arsenic" (which would include the MMA omponent) is most relevant because the arsenic species present in the environment depends entirely on thenvironmental conditions of the site (i.e., redox potential, pH, biological processes, etc.). Once arsenic residues fromecomposing foliage of treated trees are introduced into soil, they enter the "arsenic cycle" and could result in anyumber of arsenic species dictated by the environmental conditions of the site. If only one or a few arsenic species

monitored, rather than total arsenic, exposure could be underestimated. For national registrations, the PMRA must

onsider that environmental conditions are variable across Canada and cannot rely on the observed speciation at onarticular site. When the estimated or measured concentrations of total arsenic in the soil are comparable toackground concentrations, then it is concluded that environmental risks of MSMA used in forestry are comparablehe natural or baseline risk. The PMRA's conclusion, that the predicted negligible increase in arsenic concentrationsoil is comparable to background concentration, is supported by field studies (Newton 1986, Norris et al. 1983).

With regard to monitoring human exposure to arsenic, trivalent species are more unstable intermediates that are noeadily detected or quantified relative to other arsenic metabolites, and there is potential for interconversion. Thus,nalysis of one species in the absence of others could underestimate exposure. Accordingly, for regulatory purposeotal arsenic is measured and/or considered when evaluating human exposure.

Question 10: What measurements are employed by the PMRA, or its delegate, to assess the movement inecosystems of arsenic derived from applications of MSMA?

Response 10:

he data required from the registrant by the PMRA in a pre-market assessment are generated from controlledaboratory and field studies, which are conducted under approved guidelines and good laboratory practices. They arsed to determine the persistence, mobility, and bioconcentration potential of a pesticide and its major transformatiroducts in the environment. The types of data required may vary depending on where the pesticide is used. Some hese studies, such as hydrolysis, photolysis, aquatic and soil metabolism, and terrestrial dissipation, are routinely

onducted for all outdoor use pesticides.

Mobility studies attempt to predict the potential of the pesticide to volatilize into the atmosphere, move into groundurface waters, or bind to soil. Mobility studies, which include leaching, adsorption / desorption, and volatilizationrovide information on the mode of transport and eventual destination of the pesticide in the environment. Scientistan predict the degree of pesticide mobility in the soil from data generated from leaching and adsorption / desorptitudies.

ield studies, which identify the environmental dissipation processes, assess the transformation, transport, and fate esticides under actual use conditions with typically applied pesticide product at representative field sites. Thesetudies characterize the relative importance of each route of dissipation of the pesticide. Data generated from fieldissipation studies can provide more realistic estimates (albeit limited in time and space) of the persistence andransport of a pesticide when the product is applied under actual use conditions.

or re-evaluation of a pesticide, the PMRA also reviews published literature. In the case of arsenic, there are veryecent comprehensive reviews of the environmental behaviour of inorganic and organic arsenic compounds introduo the terrestrial environment (including MSMA). The summary of Dost (1995) of the fate of MSMA is a goodummary and relevant to the use pattern in question. The reviews by ATSDR (2000) and WHO (2001) do notontradict the conclusions of Dost (1995) on the environmental fate of MSMA.

Question 11: What are the effects of MSMA on small mammals, cavity-nesting birds including woodpecker


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or insects, including honey bees?

Response 11:

mall mammals that inhabit forested areas can be exposed to arsenic by consuming plants that contain arsenicesidues. Terrestrial plants may accumulate arsenic by root uptake from the soil and certain species may accumulatubstantial levels (ATSDR 2000). Yet even when grown on highly polluted soil or soil naturally high in arsenic, thrsenic level take up by the plants is comparatively low (ATSDR 2000). Therefore, dietary exposure of arsenic to

mall wild mammals is expected to be low. The lack of expected exposure is supported by field studies, where arseesidues in small mammals from MSMA-treated areas (Norris 1974, Ghassemi et al. 1981) are comparable to arsenoncentrations in mammals from background sites (Elfving et al. 1979, Ismael and Roberts 1992, Norris 1985).

All insects residing in the tree at the time of application are expected to die (since insects are the target organism). rap tree approach (pheromone attractant) does not draw species other than the target organism to the insecticide (D995). Therefore, adverse effects on honeybees are not expected due to lack of exposure. Adverse effects on insecthe soil or on the forest floor are not expected due to the expected negligible increase of total arsenic in the soilelative to background concentrations.

irds can be exposed to arsenic by excavating insects residing in the treated tree. Woodpeckers are known to obtainnsects from standing dead timber, whereas other woodland birds occasionally take insect food from the surface ofead wood. In consultation with the PMRA, Environment Canada is currently researching both exposure (arseniconcentrations and speciation in beetles and in food consumed by nestlings) and effects of MSMA (reproductiveuccess and health) on breeding and nestling woodpeckers.

he impact of MSMA on wildlife was considered prior to its registration in 1970. The outcome of the assessment dot raise any concern that would result in the denial of registration of MSMA. The impact of MSMA on wildlife asesult of forest use was also assessed in 1981 by the U.S. EPA (Ghassemi et al. 1981) and in 1995 by BC Ministry orests (Dost 1995). The conclusion in both reviews was that proper use of MSMA in forestry is unlikely to harm

wildlife. In the 33 years since MSMA was first registered in Canada, there have not been any reported wildlifencidents. The lack of reported incidents in Canada is attributed to the precise and restricted application of MSMA he consequent small contribution of arsenic relative to background concentrations.

Question 12: What are the risks of arsenic exposure and subsequent toxicity arising from a forest fire

involving MSMA-treated trees, to both forest firefighters and adjacent communities? What arthe relevant arsenic-containing combustion products from the burning of an MSMA-treated tr

and what is their toxicity?

Response 12:

he review of MSMA by Dost (1995) included an evaluation of the systemic toxicity and cancer risk as a result of ombustion of MSMA-treated wood under three different scenarios: domestic stove emission, open burning of slash

waste, and burning of mill waste. The risk posed by the burning of MSMA-treated trees as a result of forest fireswould also be accounted for in these scenarios. This report concluded that no significant exposures to arsenic wouldxpected and that there was unlikely to be any increased health risk due to combustion of MSMA-treated trees,pecifically. Although this report is several years old and does not include more recent information with respect to ecent research conducted by Dr. Cullen and others, the PMRA considers that this assessment still holds relevance he forest fire scenario, given the conservative assumptions on which the assessment was based. In addition, theMRA shares Dost's assertion that the greater hazard would more likely be the exposure to natural combustionroducts of the wood itself.


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Question 13: What is the potential exposure of a logger cutting, say, 100 treated trees in a day, and breathinsmoke from the incineration of their branches? If a logger becomes ill from absorbing toxic lev

of arsenic, what system is in place for estimating his or her exposure, monitoring its source, anproviding prompt and effective treatment?

Response 13:

With respect to burning treated logs, Dost (1995) has assessed the systemic toxicity and cancer risk as a result of th

ombustion of MSMA-treated wood under three different scenarios (domestic stove emission, open burning of slaswaste, and burning of mill waste). The eventualities of forest fires and the fuelling of beehive burners with arsenic-ontaminated wood would be included in these scenarios. It was concluded that no significant exposures to arsenic

would be expected and that there was unlikely to be any increased health risk. Please note that the PMRA does notoutinely conduct prospective risk assessments for scenarios of misuse / lack of compliance and does not support thurposeful burning of arsenic-contaminated wood (as with CCA-treated wood). Furthermore, in the environmentalppeal [2001PES-003: Josette Wier vs. Deputy Administrator Pesticide Control Act, (Minister of Forests, Moriceorest District, Permit Holder)], the Permit Holder has indicated that MSMA-treated trees are not to be removed an

heir bark is not burned. The provincial permit for MSMA treatment in the Morice Forest District (Permit No. 402-1/03) also requires each individual treated tree to be marked, prior notification that a specified area is to be treatedubstantial buffer zones from water and stipulates that only trained and provincially licensed personnel can apply t

roduct. Concerns regarding the lack of compliance with posted areas should be raised with provincial authorities.

Question 14: Have public health officials been warned of possible dangers associated with either work- relat

or forest fire exposures to MSMA-treated wood?

Response 14:

ee responses to Questions 12 and 13. The PMRA has determined that, based on current information, use of thisroduct in forestry does not pose an unacceptable risk of harm to human health or the environment. As outlined in rovincial permit for MSMA (Permit No. 402-582-01/03) Public Notification is required.

Question 15: When is re-registration of MSMA scheduled by the US EPA? If such re-registration is being

scheduled earlier than originally planned, does this not imply increasing evidence of hazardsassociated with this product? If such urgency is warranted in the U.S., of what relevance is the

precautionary principle to the PMRA while a re-assessment is being conducted?

Response 15:

MSMA is currently under re-evaluation by both the PMRA and the US EPA. MSMA re-evaluation was initiated by

MRA in 2003 and is now scheduled for completion in Fiscal Year 04/05. EPA is further ahead of the PMRA in the-evaluation of the organic arsenicals, with a preliminary risk assessment originally scheduled to be released forublic comment by the US EPA in early 2002. The US EPA did not meet this deadline and are now scheduled forompletion in their Fiscal Year 2004.

he Agency is not aware of any evidence that would support the suggestion that the US EPA's re-registration ofMSMA has been scheduled earlier than originally planned. Accordingly, there is no implication of increasing evide

f hazards associated with this product.

Question 16: If MSMA fails to be re-registered in the US, how long will it take for PMRA to respond to this


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decision, and what would that response likely be?

Response 16:

he US has many more registered uses for MSMA, including residential uses and uses on food and non-crops. Sincs likely that EPA will complete their re-evaluation ahead of PMRA, should specific concerns be identified in the Essessment that apply to the Canadian forestry use, appropriate action will be taken by the PMRA in a time-line thaomparable to that of the EPA. The outcome of the re-evaluation assessment will be available to the public and

takeholders for comment.

Question 17: Is the PMRA willing to consider evidence regarding the toxicity of MSMA independent of the assessment process in the U.S.?

Response 17:

he PMRA considers all available information during the re-evaluation process. Although the PMRA has beennvolved in scientific discussions with EPA regarding the organic arsenicals, as is the case with other pesticide re-egistration decisions, each country is ultimately responsible for their final regulatory decision.

References:

Agency for Toxic Substances and Disease Registry (ATSDR). 2000. Toxicological profile for arsenic. Atlanta, GAU.S. Department of Health and Human Services, Public Health Service.

Arnold LL, Eldan M, van Gemert M, Capen, C, Cohen S. 2003. Chronic studies evaluating the carcinogenicity ofmonomethylarsonic acid in rats and mice. Toxicology 190: 197-219.

Dost FN. 1995. Public health and environmental impacts of monosodium methanearsonate as used in bark beetleontrol in British Columbia. Prepared for Ministry of Forests, Silviculture Practices Branch. Queen's Printer for Br

Columbia, 47 pp.

lfving DC, Stehn RA, Pakkala IS, Lisk DJ. 1979. Arsenic content of small mammals indigenous to old orchard soull Environ Contam Toxicol 21:62-64.

Ghassemi M, Fargo L, Painter, P, Painter P, Quinlivan S, Scofield R, Takata A. 1981. Environmental fates and impf major forest use pesticides. EPA Contract no. 68-02-3174. TRW Environmental Division, Redondo Beach, CA.

U.S. Environmental Protection Agency, Office of Pesticides and Toxic Substances, Washington, DC.

smael A, Roberts RD. 1992. Arsenic in small mammals. Environ Technol 13(11):1091- 1095.

e XC. 2001. Arsenic speciation in the environment and humans in: Environmental Chemistry of Arsenic, edited by

WT Frankenberger, Jr., Marcel Dekker, Inc., New York 95-116.

Maclauchlan LE, Borden JH, D'Auria JM, Wheeler LA. 1988a. Distribution of arsenic in lodgepole pines treated wMSMA. Western Journal of Applied Forestry 3(2): 37-40.

Maclauchlan LE, Borden JH, D'Auria JM, Wheeler LA. 1988b. Distribution of arsenic in MSMA-treated lodgepoleines infested by the mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Scolytidae), and its relationshipeetle mortality. Journal of Economic Entomology 81(1): 274-280.

Manville JF, McMullen LH, Reimer KJ. 1988. Impact and role of monosodium methanearsonate on attack androgeny production by the Douglas-fir beetle (Coleoptera: Scolytidae) in lethal trap trees. Journal of Economic


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ntomology 81(6): 1691-1697.

Newton M. 1986. Residues from organic arsenical herbicides in chemically thinned forests. Journal of EnvironmenQuality 15(4): 388-394.

Norris LA. 1985. Exposure of applicators to monosodium methanearsonate and cacodylic acid in forestry. ACSymposium Series 273: 109-121.

Norris LA. 1974. Studies of exposure of applicators and animals to arsenicals. In Norris LA, The behaviour and im

f organic arsenical herbicides in the forest: Final report on cooperative studies, USDA Forest Service PNW ForestRange Experiment Station, Corvallis, OR, p 75.

Norris LA, Canutt PR, Neuman JF. 1983. Arsenic in the forest environment after thinning with MSMA and cacodycid. Bull Environ Contam Toxicol 30: 309-316.

WHO. 2001. Environmental health criteria 224: Arsenic and arsenic compounds (second edition). Published under oint sponsorship of the United Nations Environment Programme, the International Labour Organization, and the

World Health Organization, and produced withing the framework of the Inter-Organization Programme for the SouManagement of Chemicals, 521 pp.

Date Issued: 2003-11-05

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Documents

JosetteWeirOAG Toxicity of the arsenic-based pesticide Monosodium Methane Arsenate (MSM