Comparison of Occupational
Exposure to Carbon Disulphide in a
Viscose Rayon Factory Before and
After Technical Adjustment
Petar Bulat et al.
Institute of Occupational Health, Belgrade Yugoslavia
Department 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 followup 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 Adjustments
Viscose Prep. Dept.
• General
– Improve exhaust ventilation
• Personal
– New type of fresh air RPE for viscose
preparator for entering churns
Technical Adjustments
Spinning 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 Adjustments
Bleaching 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 Data
Job 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
Present Study
Inside RPE Outside RPE
Previous
Study
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)
40.27
n=1
100.9 (75.3-185.3)
Results – exposures(mg/m3)
Present Study
CS2 concentration (mg/m3)
Day-shift
Maintenance workers
13.0 (6.5-26.0) Ci
32.4 (18.0-57.2) Co
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, nonrepetitive 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