A review of exposure assessment methods for epidemiological studies of health effects related to industrially contaminated sites

BACKGROUND: this paper is based upon work from COST Action ICSHNet. Health risks related to living close to industrially contaminated sites (ICSs) are a public concern. Toxicology-based risk assessment of single contaminants is the main approach to assess health risks, but epidemiological studies which investigate the relationships between exposure and health directly in the affected population have contributed important evidence. Limitations in exposure assessment have substantially contributed to uncertainty about associations found in epidemiological studies. OBJECTIVES: to examine exposure assessment methods that have been used in epidemiological studies on ICSs and to provide recommendations for improved exposure assessment in epidemiological studies by comparing exposure assessment methods in epidemiological studies and risk assessments. METHODS: after defining the multi-media framework of exposure related to ICSs, we discussed selected multi-media models applied in Europe. We provided an overview of exposure assessment in 54 epidemiological studies from a systematic review of hazardous waste sites; a systematic review of 41 epidemiological studies on incinerators and 52 additional studies on ICSs and health identified for this review. RESULTS: we identified 10 multi-media models used in Europe primarily for risk assessment. Recent models incorporated estimation of internal biomarker levels. Predictions of the models differ particularly for the routes ‘indoor air inhalation’ and ‘vegetable consumption’. Virtually all of the 54 hazardous waste studies used proximity indicators of exposure, based on municipality or zip code of residence (28 studies) or distance to a contaminated site (25 studies). One study used human biomonitoring. In virtually all epidemiological studies, actual land use was ignored. In the 52 additional studies on contaminated sites, proximity indicators were applied in 39 studies, air pollution dispersion modelling in 6 studies, and human biomonitoring in 9 studies. Exposure assessment in epidemiological studies on incinerators included indicators (presence of source in municipality and distance to the incinerator) and air dispersion modelling. Environmental multi-media modelling methods were not applied in any of the three groups of studies. CONCLUSIONS: recommendations for refined exposure assessment in epidemiological studies included the use of more sophisticated exposure metrics instead of simple proximity indicators where feasible, as distance from a source results in misclassification of exposure as it ignores key determinants of environmental fate and transport, source characteristics, land use, and human consumption behaviour. More validation studies using personal exposure or human biomonitoring are needed to assess misclassification of exposure. Exposure assessment should take more advantage of the detailed multi-media exposure assessment procedures developed for risk assessment. The use of indicators can be substantially improved by linking definition of zones of exposure to existing knowledge of extent of dispersion. Studies should incorporate more often land use and individual behaviour

The epidemiology of down syndrome in four counties in ireland 1981-1990

Background We conducted a descriptive epidemiological study oi Down syndrome (DS) in the four Irish counties (Dublin, Kildare, Wicklow and Galway) covered by EUROCAT registries of congenital malformations for the years 1981-1990. Methods EUROCAT registries, which cover defined populations, use multiple sources for case ascertainment Ali DS cases born between 1 January 1981 and 31 December 1990 to mothers resident in the lour counties were identified. Crude birth prevalence rates and maternal age-standardized rates (SPRs) were calculated for each county and for each year in the study period, The prevalence oi DS by maternal age grouped in five-year periods and the risk for each live-year group were also estimated. Results The crude birth prevalence for the :our counties was 18.5/10000 for all births and 18.3 for live births. There was a fall in the total number oi DS births over the decade, but less change in the crude birth prevalence owing to an increase in the proportion oi mothers aged 35 +. Galway had the highest crude birth prevalence of DS (23.5/10000) but the SPR was within average for the lour counties as a whole - 110.3, 95 per cent confidence interval (CI) 86.7-139. The risk oi having a DS child increased 70-fold from 1:1841 at age 15-19 to 1:26 at 45 years or older. Nearly half oi all DS cases (47.4 per cent) had at least one additional anomaly Conclusions The parts oi ireland covered by EUROCAT have a high birth prevalence oi DS births as compared with some other countries, but the maternal age-specific rates are not substantially different from those in large international studies

The epidemiology of down syndrome in four counties in ireland 1981-1990

Background We conducted a descriptive epidemiological study oi Down syndrome (DS) in the four Irish counties (Dublin, Kildare, Wicklow and Galway) covered by EUROCAT registries of congenital malformations for the years 1981-1990. Methods EUROCAT registries, which cover defined populations, use multiple sources for case ascertainment Ali DS cases born between 1 January 1981 and 31 December 1990 to mothers resident in the lour counties were identified. Crude birth prevalence rates and maternal age-standardized rates (SPRs) were calculated for each county and for each year in the study period, The prevalence oi DS by maternal age grouped in five-year periods and the risk for each live-year group were also estimated. Results The crude birth prevalence for the :our counties was 18.5/10000 for all births and 18.3 for live births. There was a fall in the total number oi DS births over the decade, but less change in the crude birth prevalence owing to an increase in the proportion oi mothers aged 35 +. Galway had the highest crude birth prevalence of DS (23.5/10000) but the SPR was within average for the lour counties as a whole - 110.3, 95 per cent confidence interval (CI) 86.7-139. The risk oi having a DS child increased 70-fold from 1:1841 at age 15-19 to 1:26 at 45 years or older. Nearly half oi all DS cases (47.4 per cent) had at least one additional anomaly Conclusions The parts oi ireland covered by EUROCAT have a high birth prevalence oi DS births as compared with some other countries, but the maternal age-specific rates are not substantially different from those in large international studies