High throughput exposure and risks for alternatives assessment of chemicals in toys and building products

Evaluating exposure is an important component to identify viable alternatives to harmful chemicals in products. Yet, Alternatives Assessment (AA) methods lack efficient and flexible approaches to quantify exposure for the many thousand product-chemical combinations. To address this gap, we a) develop an operational matrix-based high-throughput framework efficiently coupling multi-pathway near-field (worker and consumer) with far-field (general population) exposures
for use in AA, and b) apply it to case studies of chemicals in toys and in building materials. Method: We first determine the chemical mass in a product and calculated fractions transferred from toys or building product interior to other compartments and humans in a matrix. Inverting this matrix yields cumulative environmental transfer fractions and Product Intake Fractions (PiF) linking chemical mass taken in by humans to a unit mass of chemical in the product. We finally determine exposure doses expressed in mg/kgBW/d or on a product function basis. Our framework was applied to generate high-throughput exposure results for commonly used chemicals in toys and in building products. Results: For chemicals in toys, exposure is restricted for pathways such as dermal contact or dust that are associated with the use of a single toy of e.g. 0.4kg, but becomes substantial when considering a total mass of 18.3 kg_toys purchased per child and per year in developing countries and the related releases to indoor air. The PiF widely ranges from a median of 0.002 to a max of 0.04 (or 4%). Resulting exposure doses for product users can vary from a median of 4E-6 to 4.9 g/kgBW/d, dominated by inhalation and dermal gaseous uptake. For each product application, we are able to determine the chemical-specific contributions of pathways and population groups to overall exposure and compare the relative exposure magnitude for all chemicals in a given product. Combining these exposures with toxicity data, we are able to calculate Hazard Quotients from a median of 4E-4 to 299, identifying main chemicals of concern and ranking alternatives. For building products, resulting exposure doses for product users range from a median of 1.3E-2 to 3.7 mg/kgBW/d, and Hazard Quotients from a median of 0.7 to 222. Systematic sensitivity studies enable us to identify the most important product and chemical attributes affecting the Product Intake Fraction and produce heat maps to easily determine exposure, for use in a screening AA, as will be illustrated for chemical alternatives in several product types. The more detailed mass-balanced-based framework is readily available for use by AA practitioners to screen a wide range of product-chemical combinations.