Estimating Chronic Exposure to Steroid Hormones in Water

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Title: Estimating Chronic Exposure to Steroid Hormones in Water
Author: Hirons, Natalie Lianne
Advisors: Damian Shea, PhD, Committee Chair
Chris Hofelt, PhD, Committee Member
Patricia McClellan-Green, PhD, Committee Member
Abstract: Ecological risk assessment (ERA) is a useful process contributing to safeguarding the earth’s ecosystems. Exposure assessment is a vital component of ERAs, as chemical exposure information is used to make decisions involving ecological risk. So, the continued advancement of sampling methodology is essential to better understanding chemical exposure. While traditional sampling methodologies, including grab sampling, only capture a snapshot of exposure, the development of passive sampling devices (PSDs) has allowed for estimations of chronic contaminant exposure. For many emerging contaminants, including many endocrine disruptors, determining chronic exposure is pertinent to assessing toxicological risk, and unlike current available sampling methodologies that tend to target specific classes of compounds, a more universal PSD (uPSD) is necessary to capture both hydrophobic contaminants and more hydrophilic contaminants, such as steroid hormones. In this work, two novel PSDs, a cartridge uPSD and a fiber uPSD, were evaluated as tools to improve our understanding of chronic exposure to steroid hormones, namely estrogens and androgens, in surface waters. A number of studies have demonstrated that chronic exogenous hormone exposure in the low nanogram-per-liter range can result in irreversible alterations in development and reproduction of individual organisms, which could threaten the reproductive success of certain aquatic populations. Consequently, as hormone use in agriculture for the efficient growth and production of meat has increased and as the science community has become increasingly aware of potential hormone contamination of surface waters via wastewater effluent, increased hormone monitoring efforts have revealed the presence of hormones in surface waters. The goal of this work was to develop novel surface-water monitoring tools to quantitatively assess chronic exposure to free estrogens and androgens. Both the cartridge uPSD and fiber uPSD contained the same polymeric sorbent, Oasis HLB®; however the cartridge uPSD consisted of a porous, stainless steel casing, while the fiber uPSD consisted of a polyethersulfone membrane. Both devices were calibrated in the laboratory by using an uptake experiment, in order to determine sampling rates for all hormones, and an elimination experiment, to determine the effect of flow rate on elimination and to evaluate the suitability of using performance reference compounds (PRCs) during in situ applications. Over the 30-day uptake experiment, all hormones remained in the linear uptake phase for both devices, demonstrating that both devices have the capacity to function as time-integrative devices. Sampling rates for the cartridge uPSD ranged from 0.09 – 0.11 L/d, and sampling rates for the fiber uPSD ranged from 0.04 – 0.09 L/d. Neither device demonstrated clear correlations of sampling rates to log Kow values; however calibrations of both devices to contaminants with expanded ranges of log Kow values is necessary to confirm these results. In the 30-day elimination experiment, neither device demonstrated any effect of flow rate on elimination rate; however, for two hormones, estrone and androstenedione, a correlation was observed. These results suggest that the use of PRCs may not be necessary to correct for differences in flow rates between laboratory calibration and field deployment; however, PRCs may be necessary to monitor changes in uptake due to biofouling or temperature in situ. The final component to validating the use of both devices included field deployments in surface waters receiving inputs from wastewater treatment plants and concentrated animal feeding operations. Mean estimated water concentrations from cartridge uPSD and fiber uPSD residues closely matched mean grab sample mean concentrations of surface waters. Ultimately, these results validate that both the cartridge uPSD and fiber uPSD offer potential as tools to provide quantitative estimates of chronic steroid hormone exposure in surface waters.
Date: 2009-04-23
Degree: MS
Discipline: Toxicology
URI: http://www.lib.ncsu.edu/resolver/1840.16/462


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