Validation of Multimedia Models Assessing Exposure to PAHs—The SOLEX Study

Abstract

Polluted soils have become a public health problem. While population exposure to soil pollutants is generally quantified using multimedia models, their estimations have not been validated, and studies that attempted to do so are scarce. The objective of the SOLEX study was to compare the predictions of pyrene exposure levels (converted into 1 hydroxypyrene) computed by several models with the results of urinary 1-hydropyrene (1-HOP) assays among 110 employees working at three sites polluted during their past use as manufactured gas plants. Four models were used: AERIS (Canada), CalTOX (California, USA), CLEA (UK), and HESP (The Netherlands). Three occupational exposure scenarios--with office, mixed, and outdoor workers--were constructed, based upon job activities during two measurement campaigns, one in winter and one in summer. The exposure levels estimated by the four models could differ markedly (from 7 up to 80 times) according to the exposure scenario. Also, the predominant exposure routes differed according to the model (direct soil ingestion for HESP and CalTOX, inhalation for AERIS, and dermal absorption for CLEA). The predictions of CalTOX are consistent with the 1-HOP measurements for all the scenarios. For HESP, the consistency is observed for the scenarios, office and mixed, for which the pyrene level in the soil is low. AERIS and CLEA yield results that are systematically above the 1-HOP measurements. This study confirms that validation of the models is crucial and points out to the need to proceed to assess components of the models that are the most influential using appropriate statistical analysis in combination with true field data.

An Interagency Comparison of Screening‐Level Risk Assessment Approaches

“…Results are similar to those from several other studies (Brock et al , 2003; Dor et al , 2003; Thiessen et al , 1997; Mills et al , 1997; CMHC, 1997), which suggested that at a smaller scale, it is the assumptions an assessor makes, based on his or her judgment, which is of primary importance in the assessment of exposure and risk. At a larger scale, judgment and policy rather than science are responsible for choices such as that of TRV, which result in the greatest variability among agencies and on the assessment of risk altogether.…”

“…Dor et al (2003) compared exposure estimates from four multimedia human exposure models: AERIS (Canada), CalTOX (United States), CLEA (United Kingdom), and HESP (The Netherlands). Exposure to the PAH pyrene was estimated using multiple exposure scenarios.…”

Site Contamination Health Risk Assessment Case Study Involving Tenant Relocation from a Former Gasworks Site

“…This biomarker of personal PAH exposure (which measures the metabolite of pyrene, a common component of PAH mixtures and was at 2 to 4 time greater levels than BaP levels in samples) was extensively used in occupational settings, where worker exposures to pyrene in air and via the skin were found in good agreement with measurements of urinary 1-OHP (Bouchard & Viau, 1999;Brandt & Watson, 2003;Dor et al, 2003). Environmental measurements were also reported in various subpopulations (Gundel et al, 1996;Jongeneelen, 2001) and in large-scale population surveys in the United States (NHANES, 2004;Huang et al 2004).…”

Model framework for integrating multiple exposure pathways to chemicals in household cleaning products

“…Briefly, the CalTOX model considers chemical transformation in the environment and uses biotransfer and bioconcentration factors. The CalTOX model has been widely used for environmental contaminant distributions and multimedia exposure and risk assessments . The model can estimate direct inhalation exposure from environmental releases to ambient air and also track indirect exposures through food or water ingestion attributable to the environmental releases (e.g., surface water) in a particular study area.…”