LABORATORI DEL CENTRE DE MEDI AMBIENT
D.E.Q. (E.T.S. D’ENGINYERIA INDUSTRIAL BARCELONA)
M.G. Rosell 1 , A. Carrasco 2 , E. Gallego 3
1 Centro Nacional de Condiciones de Trabajo. INSHT. C/Dulcet, 2-10. E 08034 Barcelona. e-mail:
2 ACCIONA Facility Services. Departamento de Seguridad y Salud, Pº Zona Franca, 69-63. E 08038. Barcelona e-mail:
3 Laboratori del Centre de Medi Ambient. Universitat Politècnica de Catalunya (LCMA-UPC). Avda. Diagonal, 647. E 08028 Barcelona. e-mail:
Automotive painting cabins are cleaned with several solvents, being great part of them mixtures of volatile organic compounds (VOCs), where the three xylene isomers are the most important constituents. To evaluate the work-related exposition of the cleaners that use these mixtures of solvents, xylenes have been determined in the working ambient air as well as its metabolite,
VOCs and to know the working conditions of the cleaners, but also to evaluate the effectiveness of personal protective equipment (PPE), the engineering control and the work practices.
The xylenes have been chosen as indicators of exposition because they are the main components in the cleaning solvents used, with a level of concentration between 50% and 85%.
The Xylenes have an occupational exposure limit (8 h TWA) of 50 ppm (221 mg/m 3
3
exposure index (BEI) for xylenes is the sum of the total methyl hippuric acids in urine at the end of the work-shift, being the value 1500 mg/g creatinine.
The study was carried on in two different automotive companies, Company A and Company B. A total of 12 personal air samples and 32 urine samples (both from exposed and non exposed workers) were taken. In addition to that, a query form was filled by each employee to determine personal aspects that could interfere in the study (e.g. smoking habits). The air samples were analyzed by gas chromatography (NIOSH Analytical Method 1501) and the urine samples by HPLC (Method MTA/MB-022/A95 INSHT).
•Gas phase VOCs were dynamically sampled connecting a solid sorbent tube (coconut shell charcoal, 100 mg / 50 mg) to an air collector pump sampler SKC whit a flow rate of 0.2 L/min.
The diffusive sampling was carried out with an ORSA 5 ® (Dräger). Both sampling tubes were extracted with CS
•The urine samples were taken at the end of the work-shift.
2
(1 ml for Charcoal tubes and 2 ml for diffusive samplers) during 30 min.
65
60
55
50
45
40
35
30
25
20
15
10
5
0
100
95
90
85
80
75
70
A Company n-butyl acetate ethyllbenzene
1-methoxy-2-propanol m+p-xylene
2-butoxyethanol
Column: DBWax (60 m x 0.53 mm x 1 µm)
Oven: 40 ºC during 6 min, then at
2 ºC/min until 100 ºC
Injector: 200 ºC
FID Detector: 250 ºC
Injection volume: 1 µl
1-propanol o-xylene
25
20
15
10
5
0
45
40
35
30
100
95
90
85
80
75
70
65
60
55
50
15 20
Time (min)
25 30 35
B Company m+p-xylene butyl acetate ethylbencene o-xylene limonene isobutanol
1-methoxy-2-propanol toluene
15 20
Time (min)
1,2,4-trimethylbenzene
25 30
A Company
Diffusive sampling
ORSA (7 h)
ΣXylene isomers
P - 1
P - 2
P - 3
P - 4
P - 5
P - 6
P - 7
Environmental
TWA for long term exposure mg/m 3 ppm
24.0
5.4
29.4
2.6
6.6
0.6
8.5
3.1
12.1
11.4
15.9
1.9
0.7
2.7
2.6
3.6
221 50
Active sampling
Charcoal tube
(15 min)
P - 1
P - 2
STEL for short term exposure
ΣXylene isomers mg/m 3 ppm
4.6
1.0
8.2
442
1.8
100
B Company
Diffusive sampling
ORSA (7.5 h)
P - 1
P - 2
P - 3
P - 4
P - 5
P - 6
P - 7
P - 8
P - 9
TWA for long term exposure
ΣXylene isomers mg/m 3 ppm
304.0
68.9
427.2
96.7
551.9
125.0
73.0
16.5
368.7
83.4
20.8
4.7
66.6
15.1
350.4
80.5
550.5
124.6
221 50
Active sampling
Charcoal tube
(15 min)
P - 1
P - 5
P - 8
P - 9
STEL for short term exposure
ΣXylene isomers mg/m 3 ppm
105.4
23.8
157.4
249.7
35.6
56.5
516.0
442
116.8
100
35
Urine/creatinine/environment
R
2
= 0,874
2500
2000
1500
1000
500
0
0 100000 200000 300000
Xylenes (ug/m3)
400000 500000 600000
Significant correlation observed between the metil hipuric concentration in urine (mg/g creatinine) and the concentration of the xylenes in ambient air (µg/m3) (F-Snedecor, p <0.05).
Mobil phase: 9:1 Buffer solution: ACN:acetic acid (pH 2.8) Flow 1 m/min
Column: Sinergy 4 µ Hydro (150 mm x 4.6 mm)
Injection volume:10 µL
Detector: PHD, at 254 nm
Methyl hippuric acid Minimum Maximum Mean
SD
A Company
All workers
No smokers
All workers
No smokers mg/l mg/g creatinine mg/l mg/g creatinine mg/l mg/g creatinine mg/l mg/g creatinine
1.5
2.7
1.5
2.7
32.8
14
53.8
14
Non exposed
70.3
67.3
70.3
67.3
Exposed
357.2
142.3
286.4
133.2
21.6
18.7
18.6
17.2
134.5
57.8
131.6
56.1
±
±
±
±
±
±
±
±
23.1
20.4
22.5
19.2
93.9
35.9
80.7
32.3
B Company
All workers
No smokers
All workers
No smokers
Median
Methyl hippuric acid Minimum Maximum Mean
SD
Non exposed mg/l mg/g creatinine
4.8
4.4
47.6
40.4
15.7
12.4
±
±
11.4
9.1
mg/l mg/g creatinine
7.3
5.2
28.7
19.8
14.3 ± 6.7
11.4 ± 4.5
Exposed
10412 2306.1 ± 3247.8
mg/l mg/g creatinine mg/l mg/g creatinine
181.2
229.3
181.2
229.3
2042.5
938.9 ± 664.3
3717.4
1463.7 ± 1392.3
2042.5
890.9 ± 667.8
Median
13.1
9.9
13.1
9.9
886.3
646.9
864.7
612.2
88.9
54.3
91.7
54.8
11.3
10.6
9.9
10.3
Even though the three xylene isomers are the main constituents of the solvents used in the cleaning process, other hazardous VOCs (e.g.
sensory irritants, hazardous for masculine reproduction) have been found in ambient air samples, such as limonene and 1-metoxy-2propanol. The presence of these compounds has to be taken into account when taking protective measures for the workers.
-Significant differences have been observed in metil hipuric acid concentration in urine between exposed and non exposed workers.
-Among exposed workers, significant differences have not been observed between smokers and non smokers. This data indicates that smoking habits do not interfere in the metil hipuric burden in urine of the workers, as their exposition to xylenes through the solvent is higher than the one that comes from smoking.
-The working conditions in B Company are not adequate. They have to improve environmental air quality increasing the ventilation rates.
-A Company can be considered safe.
REFERENCES
Henry J. McDermott,Shirley A. Ness Air monitoring for toxic exposures Wiley Publishiers Science. 2007 2ond Ed.
W J Hunter, G Aresini, R Haigh, P Papadopoulos, W Von der Hude Occupational exposure limits for chemicals in the
European Union Occup. And Environ. Medecine, 1997; 54 ; 217-222
INSHT.
Límites de Exposición Profesional para Agentes Químicos en España , 2010
The
is
of methyl hipuric acids in urine at the end of working day.