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Comparison of Occupational Exposure to Carbon Disulphide
in a Viscose Rayon Factory Before and After Technical
AdjustmentPetar Bulat et al.
Institute of Occupational Health, Belgrade YugoslaviaDepartment of Public Health, University of Gant,
Belgium
Applied Occupational and Environmental Hygiene Volume 17(1):334-38, 2002
Study Objective
• Measure personal exposures to carbon disulfide in order to follow-up and verify the effect of technical modifications on worker exposures in selected departments and job titles of a viscose factory
Study approach
• Characterize exposure for different job titles by establishing TWA ambient concentrations and to compare those measurements with data obtained in a previous study. Differences in exposure between the two studies reflect the efficacy of the introduced technical improvements.
Carbon Disulfide - Chemistry
• CS2;– highly volatile liquid– MW = 76.14– Sp. G. = 1.263– VP = 300 mmHg @ 20 degree C– Explosive 1-50% v/v in air
CS2 Exposure Guidance
• OSHA– 20 ppm; C 30 ppm
• ACGIH– TWA-TLV 10 ppm (31 mg/m3)– Skin– BEI 5 mg/g creatinine
• NIOSH– 1 ppm; 10 ppm/15 minutes
CS2 Health effects - general
– Neurological– Cardiovascular– Ophthalmological– Endocrinological– Nephrological– Gastrointestinal– Reproductive dysfunction
Sampling – where and who
• 3 departments– Viscose preparation
• Viscose preparator
– Spinning• Spinner• First spinner• Day shift• Maintenance
– Bleaching• Bleaching department
Technical AdjustmentsViscose Prep. Dept.
• General– Improve exhaust ventilation
• Personal– New type of fresh air RPE for viscose
preparator for entering churns
Technical AdjustmentsSpinning Dept.
• General– Enclosures and exhaust ventilation
• spinning machines• freshly spun cakes• waste bins
• Personal– RPE
• Fresh air mask– Spinner and 1st spinner– Compulsory with spinning machines open
• Half face piece – Day shift spinner and maintenance worker– Compulsory when in spinning room
Technical AdjustmentsBleaching Dept.
• General– Too numerous and substantial to
document
• Personal– None given
Sampling and Analytical
• Personal sampling pumps– 100 ml/min– Pre & post calibrated
• Samples with > 10% difference discarded
– Total sample volume <= 25 L• Gas/vapor sampling tubes
– Charcoal tubes – 400 mg/200 mg– Serially connected to drier tube
Sampling and Analytical
• Tube handling post sampling– Ends capped– Mailed in refrigerated box
• Laboratory– Held frozen at –70 deg. C– Used NIOSH method 1600
• Desorption of tubes• GC mass spectrometry analysis
Data Integrity and Analysis
• A priori data culling– Per & post sample flow rate change
of >10%– Backup section => 10% of front
section• Statistical parameters
– Geometric mean– 95 % CI
• SPSS/PC+
Two types of Personal Samples Collected
• Outside the respirator– Shoulder or collar
• Inside the respirator– Taped to cheek – fresh air RPE– Attached to a probe on the half face
piece RPE– Sampled continuously RPE on or off
Sampling DataJob title #Inside/
# outside
# monitored/# employed
Mean sample time
Days of sampling
Viscose Preparator 15/5 6/6 84.8(71.1-101.0)
7
Spinner 41/44 32/38 100.3(94.5–106.6)
14
First spinner 4/1 1 of 2 97.3(67.7-140.1)
3
Day shift 14/13 4/10 33.6(25.5-42.8)
6
Maintenance 5/20 9/9 90.4(78.1-104.5)
3
Bleaching Dept 3/4 3/12 121.5(88.5-167.7)
3
Results – Job titles
• Found changes in job activity vs. job titles between the two studies– Viscose preparator, spinner and first
spinner were comparable– Day shift spinner, maintenance and
bleaching department were different
Results – exposures(mg/m3)
Job Title PresentInside RPE
StudyOutside RPE
PreviousStudy
Viscose Preparator
10.1(6.0-17.0)
20.8(1.3-34.44)
90.2 (62.8-139.5)14.7(9.2-20.2) Ci
Spinner 5.4(3.95-7.37)
8.11(5.71-11.53)
111.5 (93.8-132.6)
First Spinner
6.3(3.3-11.9)
40.27n=1
100.9 (75.3-185.3)
Results – exposures(mg/m3)
Present Study CS2 concentration (mg/m3)
Day-shift 13.0 (6.5-26.0) Ci
32.4 (18.0-57.2) Co
Maintenance workers 2.2 (0.6-7.9) Ci
3.9 (2.6-5.9) Co
Previous Study
Spinning cake regulator 147.2 (117.0-190.4)
Bathman 2.0 (1.1-3.6)
Cleaner 39.5 (27.1-54.5)
Still standing regulator 51.5 (42.9-61.9)
Spinning head 39.8 (32.6-48.6)
Plummer 25.9 (13.9-48.3)
Dry worker small repairs 41.4 (24.1-71.1)
Shift technician 0.6 (0.2-2.3)
Discussion
• Spinner and viscose preparator jobs very regimented and fixed -partial shift sample OK
• 60% capacity this campaign vs. full capacity on previous study
Conclusions
• Significant decrease in worker exposure from– Enclosing and ventilating spinning
machines and spun cake tables– Wearing RPE– Work organization
Conclusions
• Adjustments could be recommended in other viscose rayon factories to reduce CS2 exposures after careful study of local production process
Problems
• Sample length on variable, non- repetitive job titles
• No documentation of RPE wear time
• Day shift spinners only sampled during work on spinner machines thus overestimating their daily exposure since that task was small part of total work activity.
Problems
• No reported measure of variability– Limits use of data by other researchers or
other purposes
• No statement of confidence on GM even though stated as one of the calculations done
• Individual exposure data not reported• No reported use of sample blanks• Was best sampling strategy used
Lessons learned
• Always carefully describe work activity associated with a job title
• Always state a priori reasons for culling data samples
• Play close attention to sampling methods
• Do and report what you say