Comparison of Occupational Exposure to Carbon Disulphide in a Viscose Rayon Factory Before and After...

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