Modeling on Many Scales - Multiscale Modeling of Exposure to Chemicals in Products

Abstract

Informing decision about chemical alternatives and related exposure to chemicals in consumer products necessitate to cover both far and near-field exposure over a range of scales and receptor populations. Building on USEtox, we present a suite of models covering a) near-field direct exposure of consumers to chemicals in products and in indoor air, and b) the far-field environmental and human exposure associated with localized chemical releases. In addition to the continent specific calculations of USEtox, a spatialized adaptation of USEtox is implemented on the multi-scale multimedia Pangea modeling platform, with 120000+ cells from 10km to global scale and using the high resolution global hydrological dataset HydroBASINS. We first apply the model to four chemicals used across Asia, selected to cover a variety of applications, volumes of production and emission, and physico-chemical and environmental fate properties: the anionic surfactant linear alkylbenzene sulphonate (LAS), the antimicrobial triclosan (TCS), the personal care preservative methyl paraben (MeP), and the emollient decamethylcyclopentasiloxane (D5). LAS emission levels and Predicted Environmental Concentrations are two to three orders of magnitude greater than for other substances. We observe a good agreement for TCS in freshwater (r=0.82, for 253 monitored values covering 12 streams), the substance with most data, whereas the model underestimate MeP sediments concentrations. Intake fraction and spatialized intakes are also determined both for the near field and spatially for environmentally mediated exposure in Australia. The direct indoor exposures are dominant, whereas we observe high spatial variation in intake fractions from 0.68 to 33 ppm for benzene emitted in ambient air, which travels over longer distances, and from 0.006 to 9.5 ppm for formaldehyde that has a more local impact. We finally discuss strengths and weaknesses of each of these complementary tools.