SVOCs in the Indoor Environment: Mechanistic Insights to Support Sustainable Product Design, Safe Use and Improved Public Health
William Fisk, Hal Levin, Tom McKone, William Nazaroff, Charles Weschler
Thousands of chemicals are currently in commercial use and hundreds more are introduced each year. Of these, only a small fraction has been assessed adequately for potential risks. REACH in Europe and the current emphasis on chemical screening and prioritizing in the United States (Cohen Hubal et al., 2008, 2010; Judson et al., 2010) highlight the critical need for improved tools to characterize and predict potential exposures associated with the indoor use of building materials and consumer products. These tools are urgently required to characterize and classify thousands of environmental chemicals in a rapid and efficient manner to prioritize testing and assess potential for risk to human health. Rapid risk assessment requires prioritization based on both hazard and exposure. In addition, the framework for design, manufacture and management of chemicals is transforming in response to society’s need for safe and effective chemicals. Prediction of potential exposures across the product lifecycle for all chemical classes and use scenarios is required under green engineering principles to minimize potential health risks to all vulnerable groups. Principles of green chemistry and sustainable chemical use require comprehensive consideration of integrated environmental, economic, and social factors.
The importance of exposures to manufactured chemicals and products in the indoor environment is broadly recognized as an important health issue in the developed world. For example:
• The Swedish government has shifted policies and reallocated resources to achieve sixteen long-term environmental goals, among them “a non-toxic environment,” and “a good built environment” (see http://www.regeringen.se/sb/d/5775); and
• The U.S. Department of Housing and Urban Development (HUD) announced HUD’s Healthy Homes Strategic Plan in June 2009. The HUD Deputy Secretary joined the Acting Surgeon General in launching a coordinated national effort to produce healthier housing, as they issued a national “call to action” to confront the prevalence of home-related preventable diseases.
Consideration of the indoor uses and sources of chemicals is critical to achieving the objectives of green chemistry. Of special interest are semi-volatile organic compounds (SVOCs) including plasticizers, flame retardants, and pesticides. SVOCs have been associated with adverse health outcomes including endocrine disruption in laboratory animals and in early-stage environmental epidemiology studies (Birnbaum, 2010; Rudel et al., 2009; Rudel and Perovich, 2009; Howdeshell et al., 2008; Jaakkola and Knight, 2008; Bornehag et al., 2004). SVOCs are released from a vast range of building materials and consumer products, and are found in essentially all environmental media including food, saliva, air, dust, water, and blood (Weschler and Nazaroff, 2008; Rudel and Perovich, 2009). Important considerations required to evaluate and manage the health risks of indoor SVOCs include:
1. Approaches for incorporating information on indoor sources and fate of SVOCs for rapid prioritization;
2. Exposure information for SVOCs in the indoor environment required to inform toxicity testing design and interpretation of real-world health risks;
3. Exposure considerations across the lifecycle, but with a particular focus on the indoor residential environment to inform chemical and product design.
A “Pilot” Workshop on SVOCs in the Residential Environment (SVOC Workshop 1) was held at EPA in Research Triangle Park in August 2009. Using one class of SVOCs (phthalates) as an example, a strategy was proposed for linking information on exposure potential for SVOCs in the indoor environment with information on hazard for rapid chemical prioritization and risk characterization. This strategy provided a tiered approach for rapid exposure-based screening followed by targeted modeling and measurement to develop a mechanistic understanding of important physical-chemical-biological processes required to predict exposure and risk associated with SVOCs used or emitted in the residential environment. In this workshop (SVOC Workshop 2) our specific objectives are to:
• Interrogate and generalize the framework proposed in SVOC Workshop 1 by considering a broad range of SVOCs to demonstrate the extent to which mechanisms along the source-to-dose continuum are controlled by physical/chemical properties of the SVOCs or their metabolites;
• Consider extension of framework for a holistic systems-based approach that enables relevant processes to be linked across the source-to-dose continuum, adjusting the scales of the various mechanistic processes so that these can be appropriately integrated;
• Consider extension of framework to evaluate potential exposures across the product lifecycle for all chemical classes and for all use scenarios to inform design, evaluation and risk management;
• Propose screening-level, rapid exposure assessment approaches based on simplified forms of mechanistic exposure models.
Indoor Air Institute (William Fisk, Hal Levin, William Nazaroff)
American Chemistry Council (ACC) (Tina Bahadori)
EPA ORD (Linda Sheldon and Roy Fortmann)
EPA NCCT (David Dix)
EPA Indoor Environment (Laureen Burton)
1. JC Little, CJ Weschler, W Nazaroff, Z Liu, EA Cohen Hubal, Rapid methods to estimate potential exposure to semivolatile organic compounds in the indoor environment, Environmental Science & Technology, doi: 10.1021/es301088a. Download here
2. WW Nazaroff, CJ Weschler, JC Little, EA Cohen Hubal, Intake to production ratio: A measure of exposure intimacy for manufactured chemicals, Environmental Health Perspectives, http://dx.doi.org/10.1289/ehp.1204992 Download here
3. H-M Shin, TE McKone and DH Bennett, Intake fraction for the indoor environment: a tool for prioritizing indoor chemical sources, environmental science and technology dx.doi.org/10.1021/es3018286. Download here
Workshop Location and Dates
EPA, Research Triangle Park, North Carolina
January 5—7, 2011
Download the draft agenda here
Download the draft paper here
Download the workshop summary here
The agenda and most of the presentations are available at http://epa.gov/ncct/expocast/svoc_agenda.html
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