Biomedical subjects

Derk H Brouwer

Publications and source records attributed to Derk H Brouwer.

7 recordsLinked to original sources

PubMed2006

Size selective dustiness and exposure; simulated workplace comparisons.

A simulated workplace study was conducted to investigate the relation between inhalation exposure and dustiness determined with a rotating drum dustiness tester. Three powders were used in the study, i.e. magnesium stearate, representing a very dusty powder, and aluminium oxide and calcium carbonate, representing low and very low dusty powders, respectively. Two scenarios of handling small volume of powders were included; sweeping/cleaning and scooping/weighing/adding. Size-selective dust exposure was assessed using MultiDust (dual-fraction) IOM and RespiCon sampling heads. For the present operation scenarios, dustiness showed itself to be the major determinant of exposure and explained approximately 70% of the exposure variances. The ratios of respirable and inhalable fractions as determined by dustiness tests were comparable with the ratios observed for exposure. The results emphasize the relevance of dustiness as a parameter to characterize substances according to potential for exposure.

Air Pollutants, Occupational↗

PubMed2005

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.

Air Pollutants, Occupational↗

PubMed2005

Concepts of skin protection: considerations for the evaluation and terminology of the performance of skin protective equipment.

This article proposes a common language for better understanding processes involved in dermal exposure and skin protection. A conceptual model has been developed that systematically describes the transport of agent mass from sources, eventually resulting in "loading" of the skin surface or the skin contaminant layer. In view of a harmonized glossary of exposure terminology this is considered the exposure surface. Loading is defined as agent mass present in this layer divided by the exposure surface area. Skin protective equipment (SPE) is meant to reduce uptake, that is, an agent crosses the absorption barrier of the skin, by intervening in the processes of loading the exposure surface; however, the design of the equipment may fail to cover skin surface entirely. In addition, part of the mass intercepted by the SPE may reach the skin surface either by permeation, penetration, or by transfer when touching the contaminated exterior of the SPE. Evaluation of SPE performance has earlier focused on chemical resistance performance testing for permeation, penetration, or degradation of SPE-materials. In use-scenario practice, however, all processes will occur concurrently. Thus, SPE field performance evaluation including user-SPE interaction complementary to material testing is warranted. Results of laboratory testing for SPE-materials are reported as substance-specific breakthrough times and permeation rates. SPE field performance should be evaluated for reduction of either uptake or parameters that reflect the outcome of dermal exposure. Ideally, this should be based on the results of intervention-type workplace studies, for (e.g., assessment of exposure loading). The level of reduction can be expressed as a protection factor (ratio without/with SPE) for different parameters of dermal exposure or uptake. It is concluded that for evaluation of SPE-type performance, generic protection factors can be derived for substance-independent processes (e.g., reduction of exposure loading) but not for substance-specific reduction of uptake.

Environmental Monitoring↗

PubMed2004

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.

Aerosols↗

PubMed2004

Dermal exposure during filling, loading and brushing with products containing 2-(2-butoxyethoxy)ethanol.

INTRODUCTION: Limited quantitative information is available on dermal exposure to chemicals during various industrial activities. Therefore, within the scope of the EU-funded RISKOFDERM project, potential dermal exposure was measured during three different tasks: filling, loading and brushing. DEGBE (2-(2-butoxyethoxy)ethanol) was used as a 'marker' substance to determine dermal exposure to the products that workers were handling. METHODS: Potential whole body exposure was measured using self-constructed cotton sampling pads on 11 body locations. Cotton gloves were used to determine the contamination of both hands. Bulk samples were collected to determine the concentration of DEGBE so as to be able to calculate exposure to the handled product. RESULTS: A total of 94 task-based measurements were performed, 30 on filling, 28 on loading and 36 on brushing, which resulted in potential dermal hand exposure to the handled product of 4.1-18 269 mg [geometric mean (GM) 555.4, n = 30], 0.3-27745 mg (GM 217.0, n = 28) and 11.3-733.3 mg (GM 98.4, n = 24) for each of the scenarios, respectively. Potential whole body exposure to the product during filling and loading ranged from 1.67 to 155.0 (GM 15.2, n = 9) and <LOD to 176.2 (GM 0.30, n = 10). Because of sampling and analytical problems, whole body exposure during brushing could not be determined. CONCLUSION: Dermal exposure during filling and loading were of the same order of magnitude, while brushing resulted in much lower exposure levels, probably due to differences in work activities and work precision. For each of the scenarios, contamination was mainly found on the hands, representing up to 96% of the total exposure for filling. For filling and loading the most important source of variability in exposure was due to between-company variability rather than to either between-worker or within-worker variability. The pooled between-worker variability was the most important source of variability in dermal exposure levels for the brushing scenario.

Analysis of Variance↗

PubMed2003

DREAM: a method for semi-quantitative dermal exposure assessment.

This paper describes a new method (DREAM) for structured, semi-quantitative dermal exposure assessment for chemical or biological agents that can be used in occupational hygiene or epidemiology. It is anticipated that DREAM could serve as an initial assessment of dermal exposure, amongst others, resulting in a ranking of tasks and subsequently jobs. DREAM consists of an inventory and evaluation part. Two examples of dermal exposure of workers of a car-construction company show that DREAM characterizes tasks and gives insight into exposure mechanisms, forming a basis for systematic exposure reduction. DREAM supplies estimates for exposure levels on the outside clothing layer as well as on skin, and provides insight into the distribution of dermal exposure over the body. Together with the ranking of tasks and people, this provides information for measurement strategies and helps to determine who, where and what to measure. In addition to dermal exposure assessment, the systematic description of dermal exposure pathways helps to prioritize and determine most adequate measurement strategies and methods. DREAM could be a promising approach for structured, semi-quantitative, dermal exposure assessment.

Environmental Exposure↗

PubMed2002

Removing pesticides from the hands with a simple washing procedure using soap and water.

Crop activities lead to dermal exposure of workers to pesticides. The efficacy of hand washing as a control measure is unknown. The efficacy of water and soap was studied for some pesticides and exposure situations. Pre-washing contamination levels in field studies were calculated from foliar residues by models using transfer factors. Between 24.5% and 50.7% of the calculated prewashing contamination was removed in two field studies with three pesticides, with coefficients of variation between 43% and 72%. In a human volunteer study, on average 45.8% and 85.7% was removed for two pesticides (coefficients of variation 6% and 7%). No influence of 'washing vigour' was found and efficacy did not depend on pre-washing contamination levels. The combination of field studies and laboratory experiments was successful, partly compensating for weaknesses in both approaches.

Adult↗