Annals of Occupational Hygiene Advance Access originally published online on March 2, 2004
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Ann. occup. Hyg., Vol. 48, No. 3, pp. 203-208, 2004
© 2004 British Occupational Hygiene Society
Published by Oxford University Press
Dermal Exposure to Styrene in the Fibreglass Reinforced Plastics Industry
1 Department of Occupational and Environmental Medicine, University Hospital of Northern Sweden, SE-901 85 Umeå; 2 National Institute for Working Life, SE-907 13 Umeå, Sweden 3 Present address; Alcontrol Laboratories, PO Box 6519, SE-906 12 Umeå, Sweden
Received 28 April 2003; in final form 30 June 2003; published online on 2 March 2004
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Objectives: The aim of this study was to assess the potential dermal exposure to styrene in the fibreglass reinforced plastics industry. Methods: Assessment was performed during spraying and rolling using a patch sampling technique. The patch was made of charcoal sandwiched between two layers of cotton fabric. Samplers were fastened at 12 different spots on a sampling overall, each spot representing a body area. One patch was fastened at the front of a cap. A patch fastened to a string worn around the neck assessed the exposure at chest level inside the clothing. Patches were fastened to cotton gloves at sites representing the dorsal side and the palm of the hand to evaluate exposure on these areas. Following sampling the patches were solvent desorbed and styrene was analysed by gas chromatography flame ionization detection. Results: The potential body exposure for the participating individuals was between 544 and 17 100 mg/h with a geometric mean (GM) of 3780 mg/h. The legs, arms and outer chest in general had the highest exposures. The left and right hands had mean (GM) exposures of 344 and 433 mg/h, respectively. Styrene was determined for the patch at the inside of the clothing, indicating contamination of the dermal layer. Conclusions: The charcoal patch can be used to evaluate potential exposure to styrene. The results indicate that the dermal layer of the worker is exposed to styrene. Precautions should be performed to reduce dermal exposure.
Keywords: dermal exposure; patch sampling; styrene
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
In the fibreglass reinforced plastics industry a styrene formulation mixed with glass fibre is used in the production of different kinds of goods. The styrene formulation consists of
25–50% styrene monomer, 50–75% unsaturated styrene resin and a few per cent of a hardener, usually methyl ethyl ketone peroxide. A mixture of the styrene formulation and glassfibre is sprayed onto an object or a mould. During spraying the aerosol formed may either impact on the surface being sprayed or may remain in the air compartment until deposition on other surfaces or onto the workers clothing or skin. Following spraying the object is hand-laminated to expel air pockets and to produce a relatively smooth surface to the product. During laminating the worker is exposed to styrene vapour emitted from the object and most likely splashes and droplets from the hand-held rolling tool. In addition, touching of objects, tools and other contaminated surfaces may cause deposition of a mixture of liquid styrene, styrene resin and glassfibre onto the clothing and protective gloves, respectively. Styrene permeating or penetrating the protective clothing or the gloves may then contaminate the inner clothing or the skin. Dermal absorption of styrene vapour or liquid styrene has been shown to be low or negligible among humans compared with inhalation exposure (Dutkiewicz and Tyras, 1968; Rihimäki and Pfäffli, 1978; Berode et al., 1985; Wieczorek, 1985). The authors of these studies suggest that the risk of developing systemic effects following dermal exposure to styrene is relatively low compared with the risk following inhalation exposure. However, styrene can cause skin irritation on acute exposure (Wenker et al., 2001). Allergic contact dermatitis to styrene, unsaturated styrene resin or the hardener methyl ethyl ketone peroxide has been reported among workers in the fibreglass reinforced plastics industry (Tarvainen et al., 1993; Minamoto et al., 2002a,b). If exposure by inhalation is reduced by technical improvements, such as installation of local extractors or use of personal protective equipment such as respirators, dermal exposure may still be of concern and should thus be assessed. Different methods have been used to assess dermal exposure to chemical hazards, such as skin washing and manual wiping (Brouwer et al., 2000), qualitative and quantitative fluorescence techniques (Cherrie et al., 2000) and use of surrogate skin techniques, i.e. patches or pads (Soutar et al., 2000). Polypropylene pads have been used to monitor polycyclic aromatic hydrocarbons, layers of gauze to monitor cyclohexane-soluble particulate matter and 3,3'-dichlorobenzidine (Soutar et al., 2000). Assessment of dermal exposure to a liquid such as styrene points to the use of a sampler onto which the substance is absorbed or adsorbed. In addition, the analyte should preferably be retained on the sampler during the assessment. Few studies regarding dermal exposure to volatile substances have been published. One reason may be difficulties in finding a suitable sampler. Cohen and Popendorf (1989) suggested that a sampler made of charcoal cloth could be appropriate for use in such applications, but did not perform any field studies to test the applicability of the sampler.
The aim of this study was to evaluate potential dermal exposure to styrene during rolling in the fibreglass reinforced plastics industry (DEO-unit 3, dispersion with a hand-held tool, Scenario 3.4 rolling) using a patch sampling technique.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Work process
The assessment was conducted at two industrial settings producing rowing boats and small and medium sized motorboats for leisure activities. Styrene formulation and glassfibre was sprayed onto the object with a hand-held airless spray gun. The use rate during spraying was
0.6 kg formulation and glassfibre/min. This task was carried out within a ventilated spray zone with the worker standing in the vicinity of the opening of the area (Fig. 1). Following spraying, which took 2–3 min, the individual used a hand-held roller with a short or an extended handle to smooth out the mixture of styrene formulation and glassfibre over the surface of the sprayed area (Fig. 2). At one of the work places spraying was performed by one of four individuals. Following spraying he and his colleagues conducted rolling. They all participated in the sampling procedure. At the other company approximately 15 individuals were working within the production department. Six individuals performing spraying and rolling took part in the study. The procedure of spraying and rolling was repeated approximately two to five times depending on the product being produced. Rolling was carried out within the spray area at both of the participating companies. During sampling the workers wore a sampling overall (part no. 714500; Procurator, Malmö, Sweden). The overall was made of polyester and of the same kind normally used by the individuals as protective clothing during spraying and rolling. The overall used as protective clothing was kept hanging in the environment of the spray area when not in use and the individual switched to a new overall approximately once a week. Gloves made of leather were normally used during the spraying and laminating process and were changed approximately once a week. A few of the workers participating used a respirator with a charcoal filter during spraying, but most of them did not use a breathing apparatus.
|
|
Dermal sampling
Patches, 10 x 10 cm in size, were cut from a charcoal/cotton cloth. The cotton carrier material was printed with glue dots and covered with
180 ± 20 g/m2 of activated charcoal (Blücher GmbH, Erkrath, Germany). The samplers were preheated in an oven at 80°C overnight prior to sampling to reduce the amount of impurities possibly interfering during analysis. The back of the patch was covered with aluminium and then fastened with staples at 12 different locations on the front of a monitoring overall. Exposure of the forehead was estimated by fastening a sampler to the front of a cap. On each of two cotton gloves, two patches were fastened representing the dorsal side and the palm of the hand, respectively. The workers used these cotton gloves instead of their protective gloves, as they were unwilling to wear the cotton gloves with samplers fastened underneath or covering the protective gloves. We were also interested to examine possible exposure under the clothing. The sampling overall was of the same kind as the one normally used as a protective overall. Placing samplers close to or on the skin would thus give a relatively good picture of possible contamination under normal working conditions. Following discussion with the workers we decided to measure exposure of one body area, the chest. To monitor exposure at this point a patch was fastened to a string with small clothes pegs. The worker wore the string around the neck with the patch under the clothing close to the chest. The sampling spots are indicated in Table 1. The patches were fastened to the monitoring overall, the cap, the gloves and the string in the laboratory and transported to the premises in a box. The workers put on the overall, the gloves, the cap and the string a few minutes before the onset of sampling. If repeated sampling was carried out on the same day, the worker was dressed in a new overall, cap, gloves and string with patches already fastened. These items were kept in a closed box until use. The overall onto which the patches were fastened was used twice if not too contaminated from the previous sampling. If used again the overall was given an airing for at least 2 days before re-use. In order to evaluate whether any styrene vapour was released from the overall following airing, patches were fastened at some of the sampling spots (legs, arms and front chest) for 3 h and analysed for their content of styrene. Sampling was carried out during the work process, which comprised spraying and laminating for most of the individuals. Our intention was to estimate exposure during rolling only, but in reality this was not possible, as sampling could not be interrupted during spraying. The worker took the sampling equipment off directly after the task was completed. A few hours later he/she could perform spraying and laminating again and repeated sampling on that individual could be carried out. Sampling was performed on six different days at one of the factories and the four individuals participated on 3, 3, 12 and 12 occasions, respectively. At the other factory sampling was carried out on three different days and the six individuals participated on 1, 2, 2, 3, 3 and 4 occasions, respectively. This resulted in 45 measurements with a mean sampling time of 59 min (30–125 min). Exposure of the hands was determined on 30 of the 45 occasions with a mean sampling time of 40 min (30–125 min). Following sampling the exposed patch was transferred to a 30 ml glass bottle and the vial was sealed with a screw cap and transported to the laboratory. At the work place one or two patches were spiked with known amounts of styrene in carbon disulphide (CS2) by means of a syringe (0.6–1.0 mg). One patch was used as a field blank for that special sampling day. The spiked patches and the blank samples were treated in the same way as the exposed patches.
|
Analysis of styrene
At the laboratory, 10 ml of CS2 was added to the glass bottle with exposed patches, the field spiked or the field blank samplers already present. The patches were extracted by shaking for 30 min. An aliquot of the extracted sample was transferred to a vial and 1.0 µl was injected onto a gas chromatograph (Hewlett-Packard model 5890) by means of an automatic injector (Hewlett-Packard model 7630). The gas chromatograph was equipped with a Hewlett Packard Ultra 2 fused silica column (50 m x 0.2 mm i.d., phase layer 0.33 µm) connected to a FID detector. Nitrogen was used as a carrier gas. The temperature program was 100°C for 1 min, followed by a temperature rise of 10°C/min up to 200°C. The FID temperature was 270°C. The concentration of the analyte was determined by the external standard method and processed by Millennium® software. The detector response was linear in the range 0.1–20.0 mg/ml styrene (r2 = 0.992). If one sample showed a concentration of
20.0 mg/ml the sample was diluted to fit the calibration curve. The limit of quantification (LOQ) was determined at 10 SB, where SB is the standard deviation of the background noise of a blank sample. The LOQ from the 10 x 10 cm patch was estimated as 180 µg. The amount of styrene on patches fastened to a previously used and aired sampling overall was less than the LOQ. Field samples were solvent desorbed on the evening of the sampling day and analysed during the night and on the following day.
Test for recovery of styrene from the patch
Recovery of styrene from the patches was evaluated by a spiking experiment. A calibrated pipette was used to apply 0.909 or 909 mg onto six samplers. Following spiking the patch was put into a 30 ml glass vial and the vial was sealed with a screw cork. The patches were analysed following storage for 24 h at room temperature or 6 days at –20°C, respectively.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Recovery of styrene from the patch
The recoveries following storage of 0.909 or 909 mg at room temperature for 24 h were 100 (RSD = 27%) and 108% (RSD = 8%), respectively. Recovery following storage at –20°C for 6 days was estimated as 89 (RSD = 22%) and 110% (RSD = 14%), respectively.
Field spiked samplers showed the following recoveries: four samplers spiked with 0.6 mg, recovery 93%, RSD 0.7%; 10 samplers spiked with 0.8 mg, recovery 89%, RSD 9.0%; six samplers spiked with 1.0 mg, recovery 90%, RSD 4.6%.
Potential dermal exposure
Body parts and total body
The exposure to styrene of the individual patches showed substantial variability, with a GM of 9.20–30.8 mg/h (Table 2). Styrene surface concentration (mg/h) was calculated by multiplying the exposure of styrene on the individual patch sampler by the corresponding body area (cm2) as shown in Table 1 and dividing by the patch area of 100 cm2, giving a total exposure per body section. The total body exposure was estimated by summing the exposure on the 13 different body parts. The surface concentration was estimated to be 9.40–779 mg/h for the different body compartments (Table 2). The leg compartment had the highest styrene exposure, accounting for 35.7% (1351 mg/h) of the potential exposure. The outer chest accounted for 20.6% (779 mg/h) and the arms accounted for 22.8% (864 mg/h). The outer back accounted for 8.4% (316 mg/h), head and face for 3.2% (121 mg/h), front of neck for 0.5% (20.5 mg/h) and back of neck for 0.25% (9.40 mg/h). The inner chest had an exposure (GM) of 302 mg/h (59.4–1091 mg/h). The potential whole body exposure was between 544 and 17 100 mg/h, with a GM of 3780 mg/h.
|
Hands
The amounts of styrene on the patches representing the palms and the dorsal sides of the left and right hands, respectively, were summed. The exposures (mg/h) (GM) of the patches on the left and right hands were calculated as 164 (37.0–660 mg/h) and 206 mg/h (22.5–1104 mg/h), respectively (Table 2). The surface concentration (mg/h) was estimated by multiplying the patch exposure by the corresponding area of the left and right hands, respectively (420 cm2, Table 1) divided by the area of the two patches used on each hand (200 cm2). The GMs of the potential exposures of the left and right hands were estimated to be 344 (78.7–1388 mg/h) and 433 mg/h (46.7–2325 mg/h), respectively. There was no statistical significantly difference in exposure on the left and right hands (P = 0.160, independent t-test).
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The results from our investigation indicate that dermal exposure to styrene took place during rolling and spraying in the reinforced styrene plastics industry. Most of the exposure occurred on the worker’s legs, arms and chest. Outer back, head and face and front and back of neck were the body areas which were least exposed. This is understandable as the individual often had to bend over, or almost into, the object during laminating, resulting in contact of legs and arms with contaminated surfaces of the object being treated (Fig. 2). In addition, splashes and droplets emitted by the laminating tool probably deposited to a higher degree on the arms, legs and outer chest, respectively, compared with other areas of the body. During spraying the aerosol emitted most likely deposited to a relatively high degree on these body parts partly due to rebounding of aerosol from the object as the worker was standing relatively close to the manufactured goods (Fig. 1).
The hands had a relatively high exposure. All of the participating workers were right-handed and there was no statistically significant difference in styrene exposure between the left and right hands. The individuals used a rolling tool with a short or an extended handle during the sampling period. When using a rolling tool with an extended handle, both hands were exposed to styrene present on the tool from previous or ongoing use. When laminating the object using a short-handled roller, the workers used the left as well as the right hand. During performance of this task the hands were frequently in contact with the object being laminated.
Interestingly, the inner chest had an exposure of 39% of the exposure of the outer chest (Table 2). Splashes, droplets and/or aerosol depositing on the overall, resulting in diffusion, permeation and/or penetration of styrene vapour and styrene in liquid form through the protective clothing, may account for exposure at a relatively high degree. In addition, styrene vapour could enter via openings at the neck, the wrists, the feet and through the zip at the front of the overall, respectively.
The amount of styrene on the individual body patches and the samplers on the cotton gloves has been used to calculate the potential body and hand exposures. The calculation assumes uniform exposure of the individual body parts and that the sampler has not become saturated. The amount of styrene recovered from the field patches was in the range 1.30–567 mg (data not shown). Our spiking experiment showed that the sampler had a relatively high sampling capacity, at least 909 mg styrene, indicating that the samplers did not become saturated during the assessment. There was great variability in exposure between individual body parts as well as between individuals, which at least to some part could be explained by the assumption of uniform exposure of the body area represented by one patch. The difference in potential body and hand exposures indicates that the watchfulness and/or the skill of the worker may play a role in the final results. Other variables such as area treated, volume sprayed and condition of the equipment may be other important determinants of exposure.
The patch used in this work was made of activated charcoal sandwiched between two layers of cotton fabric. In addition to liquid styrene, styrene vapour is adsorbed causing a ‘background’ level of adsorption. The liquid fraction is likely more ‘responsible’ than the vapour for the observed dermal problems following exposure in this kind of industry. Background adsorption of vapour could thus mask liquid deposits and introduce uncertainty in estimating the retained liquid fraction. Development of a dermal sampler for volatile or semi-volatile substances, which can distinguish between vapour and liquid deposits, seems to be an interesting challenge.
We must also realize that activated charcoal has a much higher adsorptive surface than human skin. The amount of styrene adsorbed onto the patch is most certainly several times higher than the amount which could be adsorbed onto a similar area of human skin. Nevertheless, the findings demonstrate that there exists a potential exposure to styrene and that the dermal layer of the worker will probably be exposed to styrene during the work process studied. Changing the protective clothing and protective gloves on a regular basis, avoiding or minimizing contact with contaminated surfaces, reducing the exposure to aerosol during spraying and cleaning of equipment regularly are some steps to be taken to reduce the risk of dermal exposure.
Acknowledgements—Professor Jan-Olof Levin at the National Institute for Working Life is gratefully acknowledged for supplying us with the necessary analytical equipment and additional laboratory facilities. This study was performed within a European project RISKOFDERM (Project QLK4-CT-1999-01107) with financial support from the EU. The project was also financially supported by the National Institute for Working Life, Umeå, Sweden, and the Department of Occupational and Environmental Medicine, University Hospital of Northern Sweden, Umeå, Sweden, which is gratefully acknowledged.
|
FOOTNOTES |
|---|
* Author to whom correspondence should be addressed. Fax: +46-907852456; e-mail: kare.eriksson{at}vll.se
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Berode M, Droz PO, Guillemin M. (1985) Human exposure to styrene. VI. Percutaneous absorption in human volunteers. Int Arch Occup Environ Health; 55: 331–6.[CrossRef][Web of Science][Medline]
Brouwer DH, Boeniger MF, van Hemmen JJ. (2000) Hand wash and manual skin wipes. Ann Occup Hyg; 44: 501–10.
Cherrie JW, Brouwer DH, Roff M, Vermeueln R, Kromhout H. (2000) Use of qualitative and quantitative fluorescence techniques to assess dermal exposure. Ann Occup Hyg; 44: 519–22.
Cohen B-SM, Popendorf W. (1989) A method for monitoring dermal exposure to volatile chemicals. Am Ind Hyg Assoc J; 50: 216–23.[Web of Science][Medline]
Dutkiewicz T, Tyras H. (1968) Skin absorption of toluene, styrene and xylene by man. Br J Ind Med; 25: 243–4.[Web of Science][Medline]
Minamoto K, Nagano M, Inaoka T, Futatsuka M. (2002a) Occupational dermatoses among fibreglass-reinforced plastics factory workers. Contact Dermatitis; 46: 339–47.[Medline]
Minamoto K, Nagano M, Inaoka T, Ushijima K, Fukuda Y, Futatsuka M. (2002b) Skin problems among fiber-glass reinforced plastics factory workers in Japan. Ind Health; 40: 42–50.[Medline]
OECD. (1997) Guidance document for the conduct of studies of occupational exposure to pesticides during agricultural application, Series on testing and assessment report no. 9. Paris: OECD Environment Directorate.
Rihimäki V, Pfäffli P. (1978) Percutaneous absorption of solvent in man. Scand J Work Environ Health; 4: 73–85.[Web of Science][Medline]
Soutar A, Semple S, Aitken RJ, Robertson A. (2000) Use of patches and whole body sampling for the assessment of dermal exposure. Ann Occup Hyg; 44: 511–8.
Tarvainen K, Jolanki R, Forsman-Gronholm L, et al. (1993) Exposure, skin protection and occupational skin diseases in the glass-fibre-reinforced plastics industry. Contact Dermatitis; 29: 119–27.[Medline]
Wenker MAM, Kezic S, Monster AC, de Wolff FA. (2001) Stereochemical metabolism of styrene in volunteers. Int Arch Occup Environ Health; 74: 359–65.[Medline]
Wieczorek H. (1985) Evaluation of low exposure to styrene (I). Dermal absorption of styrene vapors in humans under experimental conditions. Int Arch Occup Environ Health; 57: 71–5.[Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  P. Boogaard Biomonitoring as a tool in the human health risk characterization of dermal exposure Human and Experimental Toxicology, April 1, 2008; 27(4): 297 - 305. [Abstract] [PDF]
|
|
|
|
 |
|
 H. MARQUART, N. D. WARREN, J. LAITINEN, and J. J. VAN HEMMEN Default Values for Assessment of Potential Dermal Exposure of the Hands to Industrial Chemicals in the Scope of Regulatory Risk Assessments Ann. Hyg., July 1, 2006; 50(5): 469 - 489. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. D. WARREN, H. MARQUART, Y. CHRISTOPHER, J. LAITINEN, and J. J. VAN HEMMEN Task-based Dermal Exposure Models for Regulatory Risk Assessment Ann. Hyg., July 1, 2006; 50(5): 491 - 503. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. A. KOLSTAD, J. SONDERSKOV, and I. BURSTYN Company-Level, Semi-Quantitative Assessment of Occupational Styrene Exposure when Individual Data are not Available Ann. Hyg., March 1, 2005; 49(2): 155 - 165. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. RAJAN-SITHAMPARANADARAJAH, M. ROFF, P. DELGADO, K. ERIKSSON, W. FRANSMAN, J. H. J. GIJSBERS, G. HUGHSON, M. MAKINEN, and J. J. VAN HEMMEN Patterns of Dermal Exposure to Hazardous Substances in European Union Workplaces Ann. Hyg., April 1, 2004; 48(3): 285 - 297. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||