Assessment of occupational exposures in a general population: comparison of different methods.

Abstract

Objectives-To evaluate the relative merits of job specific questionnaires and various alternative assessment methods of occupational exposures often used in general population studies. Methods-Subjects were participants in a hospital based case-control study of risk factors for male infertility. Estimates of exposure to organic solvents and chromium, based on job specific questionnaires, generic questionnaires, self reports of exposure, an external job exposure matrix (JEM), and a population specific JEM were compared with passive diVuse dosimeter results and measurements in urine. Urine samples from the end of the shift were analysed for metabolites of toluene, xylene, several glycol ethers, trichloroethylene, and chromium. Passive dosimeter date, metabolites of specific solvents, and urinary chromium concentrations were available for 89, 267, and 156 subjects, respectively. The alternative methods and measurements in urine were compared by means of the Cohen's statistic and by computing the positive predictive value, sensitivity, and specificity of the alternative methods against measurements in urine. Results-Passive dosimeter results indicated that exposure classifications with job specific questionnaire information could discriminate between high and low exposures. The coeYcients were <0.4, so agreement between the various methods and measurements in urine was poor. Sensitivity of the methods ranged from 0.21 to 0.85, whereas specificity ranged from 0.34 to 0.94. Positive predictive values ranged from 0.19 to 0.58, with the highest values for job specific questionnaires. Conclusions-The results indicate that the implementation of job specific questionnaires in a general population study might be worth the extra expense it entails, bearing in mind the paramount importance of avoiding false positive exposure estimates when exposure prevalence is low. (Occup Environ Med 1999;56:145-151)

Variability of environmental exposures to volatile organic compounds

“…Thus, we encourage investigators to forsake microenvironmental measurements of VOCs in favor of personal measurements, a sentiment recently voiced by Kromhout and van Tongeren (2003). Since passive monitoring devices allow subjects to measure their own VOC exposures with a minimum of professional involvement (Tielemans et al, 1999;Egeghy et al, 2000Egeghy et al, , 2002Liljelind et al, 2000Liljelind et al, , 2001, this goal is realistic.…”

Personal exposure to benzene from fuel emissions among commercial fishers: comparison of two-stroke, four-stroke and diesel engines

“…Two-stroke engines are known to emit more unburned fuel (including benzene) than fourstroke or diesel engines, and the elevated personal exposures to benzene may also indicate higher levels of exposure to potentially neurotoxic hydrocarbons. The self-monitoring approach for collecting personal exposure measurements has been used successfully in several previous studies (Loomis et al, 1994;Saarinen et al, 1998;Rappaport et al, 1999;Tielemans et al, 1999;Egeghy et al, 2000;Liljelind et al, 2000). Although our participants were trained to use passive monitors, we were not able to verify that they followed the self-monitoring protocol.…”

Determinación del historial de exposiciones en la epidemiolgía ocupacional

“…La validez y coherencia de los datos obtenidos de distintas fuentes y de los métodos aplicados para determinar la exposición varían enormemente (9), incluso dentro de un único conjunto de datos (40), y en el estimador final de la exposición personal se acumulan las deficiencias de sus componentes. Por ende, la interpretación de los indicadores de exposición resultantes depende directamente de la validez de sus diferentes componentes.…”