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Alyssa Zearley Thesis.pdf (1.68 MB)

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Incorporating Diet into In Vitro Bioaccessibility Assays to Improve Prediction of Bioavailability of Soil Pb in Birds and Humans

Zearley, Alyssa
http://rave.ohiolink.edu/etdc/view?acc_num=osu1532085799038326

Abstract Details

2018, Master of Science, Ohio State University, Environment and Natural Resources.
Anthropogenic use of lead has resulted in widespread soil contamination. Exposure to lead when contaminated soil is incidentally ingested with food poses a risk to both humans and wildlife. When soil is ingested, only a fraction of total Pb is bioavailable, or absorbed into the bloodstream. Conservative soil bioavailability defaults are used to calculate exposure in the absence of bioavailability data. This often overestimates exposure and risk. Generating bioavailability data allows a more accurate representation of risk, reducing cleanup costs or making sites appropriate for a wider variety of uses. However, the animal feeding studies traditionally used to generate these data are time-consuming and expensive. Extensive research has led to development and adoption of in vitro bioaccessibility assays that simulate gastrointestinal conditions to determine in vitro bioaccessible Pb (IVBA Pb), which is then used to predict relative soil Pb bioavailability (RBA Pb). These methods simulate fasting conditions and it is unclear whether they can predict bioavailability of soil Pb consumed with food. This study sought to incorporate diet into soil Pb in vitro bioaccessibility assays to simulate exposure in wildlife incidentally consuming soil while feeding and in humans eating produce contaminated with soil. To determine whether in vitro bioaccessibility assays were predictive of RBA Pb of eight soils dosed to Japanese quail (Coturnix japonica), the soils were combined with the feeding study diet and IVBA Pb determined with three in vitro bioaccessibility methods: USEPA Method 1340 at pH 1.5, USEPA Method 1340 at pH 2.5, and a newly developed Avian Ohio State University In Vitro Gastrointestinal evaluation. All methods were predictive of RBA Pb in Japanese quail (Coturnix japonica), and diet+soil methods produced somewhat stronger relationships than soil-alone methods. Seven wildlife diets were then evaluated with a single soil in the 3 previously mentioned methods to explore the impact of different diets on IVBA Pb. IVBA Pb was lower in the more nutrient-dense stock diets compared to natural diets, suggesting risk may be underestimated when using stock diets in in vitro or in vivo toxicological assays. A new in vitro bioaccessibility assay was developed to simulate human exposure to Pb from soil-contaminated vegetables. Gastric and intestinal phase IVBA Pb was determined in eight vegetables contaminated with a smelter soil or a residential soil. Diet+soil IVBA Pb differed from soil-alone IVBA Pb and the effects of diet were dependent on phase. Future work is needed to determine which is more appropriate for simulating IVBA Pb in soil-contaminated vegetables. These first steps towards developing diet+soil in vitro bioaccessibility assays have demonstrated that diet influence IVBA Pb and should be considered when evaluating exposure. With further research, these methods will facilitate the use of RBA Pb when calculating exposure for risk assessment.
Nicholas Basta (Advisor)
G. Matthew Davies (Committee Member)
Jeffory Hattey (Committee Member)
135 p.
Environmental Science
bioaccessibility; bioavailability; risk assessment; Pb; lead

Recommended Citations

Citations

  • Zearley, A. (2018). Incorporating Diet into In Vitro Bioaccessibility Assays to Improve Prediction of Bioavailability of Soil Pb in Birds and Humans [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532085799038326

    APA Style (7th edition)

  • Zearley, Alyssa. Incorporating Diet into In Vitro Bioaccessibility Assays to Improve Prediction of Bioavailability of Soil Pb in Birds and Humans. 2018. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1532085799038326.

    MLA Style (8th edition)

  • Zearley, Alyssa. "Incorporating Diet into In Vitro Bioaccessibility Assays to Improve Prediction of Bioavailability of Soil Pb in Birds and Humans." Master's thesis, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532085799038326

    Chicago Manual of Style (17th edition)

osu1532085799038326
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