Society For Risk Analysis Annual Meeting 2017

Session Schedule & Abstracts

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Common abbreviations

PAHs & Related Compounds: Exposure and Dose-Response

Room: Salon K   1:30 pm–3:00 pm

Chair(s): Margaret Pratt

Sponsored by Dose Response and Exposure Assessment Specialty Groups

W3-I.1  1:30 pm  Comparative dietary exposure assessment of selected heterocyclic amines and polycyclic aromatic hydrocarbons through meat and bread consumption in the United States. Pouzou JG*, Costard S, Zagmutt FJ; EpiX Analytics

Abstract: Dietary exposure to two compound classes proposed as a link between meat consumption and colorectal cancer (CRC), polycyclic aromatic hydrocarbons (PAH) and heterocyclic amines (HCA), was quantified from average US meat and bread consumption. Studies reporting PAH or HCA content of cooked meats were identified via literature review. Results were pooled using linear mixed models/meta-regression to predict the concentration of two HCAs (PhIP,MeIQx), and PAH8 based on cooking methods, time, temperature, and other factors, whereas bread PAH8 was estimated empirically. Concentration models/predictors were selected using likelihood ratio tests (p<0.05). Concentrations were combined via Monte Carlo simulation with meat (beef, poultry, pork, seafood) or wheat bread consumption estimated from a US dietary survey (NHANES) to compare the mean daily consumption of PAH and HCA. Statistical significance of PAH or HCA consumption was considered when confidence in the PAH/HCA consumption being highest (PrHighest) was >95%. PAH8 concentration was not different among meats (p=0.861, beef: 3.7 ng/g, poultry: 1.1 ng/g, pork: 0.6 ng/g, and seafood: 0.4 ng/g), but was significantly impacted by cooking method (p<0.001), using open flame (p<0.001), and cooking time (p<0.001). Meat type and cooking method were significant to HCA concentration (p<0.001, pork: 4.6 ng/g, poultry: 4.3 ng/g, beef: 0.5 ng/g, and seafood: 0.02 ng/g). HCA or PAH dietary exposure was not significantly different among meats or bread. Within meat categories, only pan-frying significantly increased exposure to MeIQx in beef (6.5 ng/day, PrHighest: 99%) and poultry (12.7 ng/day, 97%). Although cooking methods affect PAH and HCA concentration, dietary exposure did not differ across meat or bread categories because of differences in consumption and cooking practices in the US. Our findings can be combined with epidemiological data to assess the consistency of evidence and comparative diet-associated risks of CRC.

W3-I.2  1:50 pm  The influence of polycyclic aromatic hydrocarbons on lung function in a representative sample of the Canadian Population. Cakmak S*, Hebbern C, Cakmak JD, Dales ED; Government of Canada

Abstract: We investigated the associations between exposure to polycyclic aromatic hydrocarbons (PAHs) and selected respiratory physiologic measures in cycles 2 and 3 of the Canadian Health Measures Survey, a nationally representative population sample. Using generalised linear mixed models, we tested the association between selected PAH metabolites and 1-second forced expiratory volume (FEV1), forced vital capacity (FVC), and the ratio between the two (FEV1/FVC) in 3,531 people from 6 to 79 years of age. An interquartile change in urinary PAH metabolite was associated with significant decrements in FEV1 and FVC for eight PAHs, 2-hydroxynapthalene, 1-, and 2-hydroxyphenanthrene, 2-, 3-, and 9-hydroxyfluorene and 3- and 4-hydroxyphenanthrene. Exposure to PAH may negatively affect lung function in the Canadian population.

W3-I.3  2:10 pm  Benzo(a)pyrene Toxicity Value Updates: Implications for Human Health Risk Assessment. Chien J*, Lemay JC; Gradient

Abstract: Polycyclic aromatic hydrocarbons (PAHs) are commonly detected in soil and sediment at former industrial sites and are often the focus of remediation efforts. However, toxicity criteria are not available for all PAHs. For carcinogenic endpoints, human health risks are assessed by assigning toxicity equivalency factors (TEFs) to carcinogenic PAHs (cPAHs) relative to toxicity of benzo(a)pyrene (BaP), which is the best characterized of the cPAHs. In January 2017, the United States Environmental Protection Agency (US EPA) published new toxicity values for BaP in its Integrated Risk Information System (IRIS). The new oral cancer slope factor (CSF) is lower than the previous CSF by approximately 7-fold. The new IRIS inhalation unit risk (IUR) for cancer is approximately 2-fold lower than the IUR developed by the California Office of Environmental Health Hazard Assessment, which had previously been used in US EPA risk assessments. US EPA also published, for the first time, non-cancer Reference Dose (RfD) and Reference Concentration (RfC) values. We examined the impacts of these updated BaP toxicity criteria on results of a human health risk assessment at an example site, where PAHs were detected in soil and groundwater. For demonstration purposes, we calculated risks from PAHs for the construction worker and the resident. As expected, the calculated incremental lifetime cancer risks (ILCRs) for both receptors were lower using the new toxicity values compared to the old values. More importantly, non-cancer hazards due to PAHs exceeded US EPA's target risk limit of one. This demonstrates that use of these new toxicity values in human health risk assessments, particularly for non-cancer endpoints, may have remediation implications for PAH sites.

W3-I.4  2:30 pm  Alternative Methods for Assessing Human Health Risks from Exposure to Polycyclic Aromatic Compounds. Chrostowski PC*; CPF Associates, Inc.

Abstract: Polycyclic aromatic compounds (PACs, including PAHs) typically occur as complex mixtures in the environment ranging from petroleum (crude and products) to coal products (tar, creosote) to food (grilled meats) to combustion products (tobacco smoke, tailpipe emissions). It is common for 50-200 individual PACs to be present in these mixtures. Advances in analytical chemistry have enabled reliable and mostly complete identification and quantitation of components of PAC mixtures, however, regulatory human health risk assessment methods have not kept pace. For example, traditional USEPA site-specific risk assessments focus on 16 priority pollutant PAHs originally designated in the 1970s. Routine regulatory analytical methods may add yet a few others (e.g. carbazole) although other commonly available non-regulatory analytical methods can easily measure >50 PACs. Thus, environmental human health risk assessments exclude most PACs present in common mixtures. Many of these compounds lack high-quality dose-response relationships, the methods fail to recognize the toxicological impact of the matrix, and rely on methods of assessment that cannot account for toxicological interactions (other than additivity) in the mixtures. Alternative methods, both biological and chemical, have been proposed by the petroleum industry and academic researchers, however, have not gained traction for regulatory health risk assessments. In some cases, the different methods yield contradictory results which detracts from the credibility of the methods being compared. This paper will review the current state-of-practice in PAC human health risk assessments, characterize the pros and cons of the different methods, apply alternative methods to real-world datasets, critically review the outcome of these applications, and present potential ways that these methods may be reconciled and used in routine regulatory risk assessments.

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