Quantitative self-assessment of exposure to solvents among shoe repair men.

Self-assessment of exposure (SAE) refers to any exposure assessment methodology wherein the worker takes an active role in establishing his or her exposure status. The objective of this study was to investigate the reliability and feasibility of SAE approaches among shoe repair workers collecting exposure data over a 3 month period. This study was conducted in 26 Dutch shoe repair shops, which were divided into two groups of SAE with different levels of expert supervision. Participants in group 1 received only written instructions on sampling methods, whereas workers in group 2 were also instructed face-to-face by an occupational hygienist. Participants were asked to do 20 (group 1) or 14 (group 2) measurements by themselves. In group 2, an additional 6 measurements in each company were conducted under supervision of an expert. Organic solvents were measured by passive samplers (3M badges) and a sum score for volatile organic compounds (VOC score) was used in data analysis. Mixed effect models and principal component analysis were used to compare concentration levels and exposure variability between group 1 and group 2. Finally, 473 out of the 520 distributed samplers (91%) were available for analysis. Measurements in group 1 were not evenly spread over the 3 month period, whereas dispersal of measurements was much better if experts were more closely involved (group 2). No significant differences in average VOC scores were found between group 1 and group 2. The exposure variability in group 1 appeared to be significantly larger than that in group 2. However, analysis within group 2 showed that no differences exist in geometric means and exposure variability between 'expert' and 'self-assessment' measurements. Thus, the study results are ambiguous with respect to the reliability of SAE, and more research is needed to corroborate and refine the present results. This new methodology can, if proven reliable, be seen as a cost-effective way of collecting exposure data.

Occupational exposure during application and removal of antifouling paints.

Exposure data on biocides are relatively rare in published literature, especially for secondary exposure. This is also the case for antifouling exposure. Therefore, a field study was carried out measuring exposure to antifouling paints. Both primary exposure (rolling and spraying) and secondary exposure (during sand blasting) were studied. Exposure during rolling was measured in boatyards where paints containing dichlofluanid (DCF) were applied. Spraying was measured in dockyards (larger than boatyards) where paints containing copper were applied. Furthermore, during sand blasting the removal of old paint layers containing copper was measured. A total of 54 datasets was collected, both for inhalation and dermal exposure data. For paint and stripped paint bulk analyses were performed. The following values are all arithmetic means of the datasets. Inhalation of copper amounted to 3 mg m-3 during spraying and to 0.8 mg m-3 during sand blasting. Potential body exposure loading amounted to 272 mg h-1 copper during spraying and 33 mg h-1 during sand blasting. For dichlofluanid the inhalation exposure loading was 0.14 mg m-3 during rolling, whereas the potential body exposure loading was 267 mg h-1 and potential hand exposure loading 277 mg h-1. The results for primary exposure compare well to the very few public data available. For the secondary exposure (sand blasting) no comparable data were available. The present study shows that the exposure loading should be considered more extensively, including applicable protective gear. In this light the findings for the potmen during sand blasting suggest that personal protective equipment should be (re)considered carefully.

An experimental study to investigate the feasibility to classify paints according to neurotoxicological risks: occupational air requirement (OAR) and indoor use of alkyd paints.

The concept of occupational air requirement (OAR), representing the quantity of air required to dilute the vapor concentration in the work environment resulting from 1 l product to a concentration below the occupational exposure limit (OEL), was considered to have potential to discriminate between paints that can and cannot be used safely. The OAR is a simple algorithm with the concentration of volatile organic compound (VOC) in the paint, a discrete evaporation factor and the neurotoxicological effects-based OEL. Conceptually, OAR categories of paints for construction and maintenance applications could be identified that can be applied manually without exceeding OELs with no appreciable room ventilation. Five painters volunteered in an exposure study aimed at testing the OAR approach in practice. Total exposure to VOC was assessed in 30 experiments during the application of 0.5 l of paint in a defined 'standard indoor paint job'. Fifteen paints were prepared, reflecting differences in solvents (percentage, volatility, toxicity) with a range of OAR levels from 43 to 819 m(3)/l. Exposure was assessed by personal air sampling (PAS). In addition, real-time air monitoring was performed. All tests were conducted at minimum ventilation rate (< or=0.33 h(-1)). PAS results were expressed as percentage of the nominal OEL and ranged from 8 to 93% for high solids and from 38 to 168% for conventional paints. In general, higher VOC contents resulted in higher exposure. High volatile paints showed a statistically significant faster increase of VOC concentration with time compared with paints containing low volatile solvents. A significant relationship between OAR value and exposure was observed (R(2) = 0.73). The experiments indicate that OAR-based classification of paints predicts and discriminates risk levels for exposure to neurotoxic paint-solvents in indoor painting fairly well.

Personal exposure to ultrafine particles in the workplace: exploring sampling techniques and strategies.

Recently, toxicological and epidemiological studies on health effects related to particle exposure suggest that 'ultrafine particles' (particles with an aerodynamic diameter of <100 nm) may cause severe health effects after inhalation. Although the toxicological mechanisms for these effects have not yet been explained, it is apparent that measuring exposures against mass alone is not sufficient. It is also necessary to consider exposures against surface area and number concentration. From earlier research it was hypothesized that results on number concentration and particle distributions may vary with distance to the source, limiting the reliability of estimates of personal exposure from results which were obtained using static measurement equipment. Therefore, a workplace study was conducted to explore the performance of measurement methods in a multi-source emission scenario as part of a sampling strategy to estimate personal exposure. In addition, a laboratory study was conducted to determine possible influences of both distance to source and time course on particle number concentration and particle size distribution. In both studies different measurement equipment and techniques were used to characterize (total) particle number concentration. These included a condensation particle counter (CPC), a scanning mobility particle sizer (SMPS) and an electrical low pressure impactor (ELPI). For the present studies CPC devices seemed to perform well for the identification of particle emission sources. The range of ultrafine particle number concentration can be detected by both SMPS and ELPI. An important advantage of the ELPI is that aerosols with ultrafine sizes can be collected for further analysis. Specific surface area of the aerosols can be estimated using gas adsorption analysis; however, with this technique ultrafine particles cannot be distinguished from particles with non-ultrafine sizes. Consequently, estimates based on samples collected from the breathing zone and scanning electron microscopic analysis may give a more reliable estimate of the specific surface area of the ultrafine particles responsible for personal exposure. The results of both the experimental and the workplace study suggest both spatial and temporal variation in total number concentration and aerosol size distribution. Therefore, the results obtained from static measurements and grab sampling should be interpreted with care as estimates of personal exposure. For evaluation of workplace exposure to ultrafine particles it is recommended that all relevant characteristics of such exposure are measured as part of a well-designed sampling strategy.