Date of Award

2013-01-01

Degree Name

Master of Science

Department

Geology

Advisor(s)

Wen-Yee Lee

Abstract

Glucocorticoids are a class of steroid hormones that can either be produced synthetically or naturally by the adrenal glands. The synthetic glucocorticoids are highly prescribed in the United States for their anti-inflammatory and immunosuppressive properties to treat a variety of ailments and diseases; however, these have been implicated in a number of adverse human conditions such as obesity, metabolic syndrome, immune-suppression, delayed puberty, adrenal insufficiency and Cushing Syndrome, among others. Ongoing research has shown that synthetic and natural hormones are transported to aquatic environments via mammalian excretion or wastewater effluent, and as a result, the release of glucocorticoids into the environment is potentially creating reproductive stress and mutations on aquatic vertebrates. The occurrence of glucocorticoids in environmental samples has only been reported worldwide in limited articles; nonetheless the studies have led to growing awareness of their potential environmental and health impacts at low concentrations ng/L. Their effects in the environment are unknown; however, the aforementioned compounds in water resources are of increasing concern due to their ability to act as endocrine disruptors.

Given that synthetic and natural estrogens have been previously found in wastewater influent and effluent for the Paso Del Norte Region, we hypothesized that glucocorticoids would be detected at significant concentrations. The objective of this research was to develop and optimize a chemical and biological method for the detection of glucocorticoids using solid phase extraction (SPE) followed by high performance liquid chromatography mass spectrometry (HPLC-MS)--in addition to a biological analysis using a 4-hour yeast assay.

Four glucocorticoids were included in this study and they are cortisone, hydrocortisone, prednisone and prednisolone. The average glucocorticoid concentrations in influent and effluent ranged from 4.62 (prednisolone/cortisone) to 15.56 (prednisone) ng/L, and from 3.43 (prednisolone/cortisone) to 12.57 (prednisone) ng/L, respectively. Prednisone had the highest levels among the four glucocorticoids in all wastewater samples potentially reflecting a high consumption of prednisone for asthma and allergy treatments in our region. For the influent samples, the finding showed that the levels of glucocorticoid in the morning hour samples were higher than that in samples collected from the rest of the day. As for the effluent samples, glucocorticoids are higher in the 12 pm samples. A 17.9 (±9.7) % estimated removal for the Northwest Wastewater Treatment Plant was calculated. To date, research has not identified a specific technology or wastewater treatment process that has the potential to completely remove glucocorticoids from wastewater effluent however anaerobic treatment is highly recommended.

Two previously hGR transfected yeast cells were tested for detecting glucocorticoids in wastewater: one with a higher promoter activity (MCY-212) in comparison to a lower promoter activity yeast cell (DSY-1345). The half maximal effective concentrations, EC50, for the glucocorticoids of interest were found to be in the μM range which is equivalent to high mg/L concentration. The results indicated that the biological analysis is not a suitable method for analyzing glucocorticoid activity in wastewater since the sensitivity of the assay was not sufficient for samples with concentrations of ng/L levels.

Even though this research was focused on the Paso Del Norte region, the presence of glucocorticoids in the environment is a worldwide problem. Semi-arid and arid regions represent 30% of the world's continental area. Limited water resources have the potential to be highly impacted by anthropogenic activities. It is important to target the removal of glucocorticoids and other environmental endocrine disruptors during wastewater treatment processes to avoid further dispersal of these contaminants of emerging concern to freshwater systems and protect the water resources for the safety of public health.

Language

en

Provenance

Received from ProQuest

File Size

75 pages

File Format

application/pdf

Rights Holder

Maria Carmen Lozano

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