>Magister Scientiae - MSc / Endocrine disrupting compounds (EDCs) are exogenous compounds/chemicals in the environment that interfere with the synthesis, secretion, distribution and function or elimination of natural hormones in the body. Environmental estrogens are a subclass of EDCs that may mimic or inhibit the effect of endogenous estrogen and can therefore influence developmental and reproductive health in humans and animals. EDCs have been reported to adversely affect the reproductive, immune, endocrine and nervous systems of wildlife and humans. The effects of EDCs include gonadal abnormalities, altered male/female sex ratios, reduced fertility and cancers of the male and female reproductive tract to mention a few. These effects are difficult to detect. Although it is essential to screen for EDCs in aqueous environmental samples, most countries have failed to implement this as part of their routine water quality monitoring programs due to various constraints such as the high cost of assays and the lack of infrastructure and skills required to do the assays. Therefore, there is a clear need for more user-friendly, more economically viable and time saving assays that can be used for routine monitoring of environmental EDCs. The aim of this study was to investigate the comparison between chemical and tissue culture methods to monitor environmental estrogens. 28 environmental water samples were collected from various sites around South Africa and analyzed for EDCs using a battery of rapid in vitro tests. Samples collected for the current study were selected based on various human impacts and also to give approximately 50% high and 50% low estrogen values. The 28 environmental water samples were separated into two groups based on the estradiol ELISA. The estradiol ELISA was chosen because estradiol is the principal estrogen found in all mammalian species during their reproductive years. For this separation, an estradiol level of 5 pg/ml was used as cut-off. Of the 28 samples investigated, 15 had estradiol levels higher than 5 pg/ml and were designated as high estradiol. The remaining 13 samples contained estradiol at 5 pg/ml or less and they were designated as low estradiol. The first objective of this study was to compare different rapid ELISAs for EDC monitoring to determine if the data obtained with these assays are similar/identical. The data obtained from the estrogenic ELISAs was related/similar and showed good correlation with each other. This is because the different estrogens are very similar and also due to the fact that the same sub-group in the population (the reproductively active females) is secreting these hormones. Therefore, an estradiol rapid assay was proposed as a first screening system for estrogens in samples. Even though there was a positive correlation between the estradiol rapid assay and testosterone rapid assay, separation of samples based on estradiol levels wasn’t a good predictor of testosterone levels in the samples. A testosterone rapid assay was therefore recommended as necessary to screen for androgens in samples. The positive correlation between the estradiol rapid assay and progesterone rapid assay was expected because both estradiol and progesterone are secreted and excreted by the same population sub-group (reproductively active females). This study also demonstrated a good predictability of separating samples containing progesterone using the estradiol ELISA. Progesterone is secreted by pregnant women, a sub-group of the reproductively active females. It is advised that a progesterone rapid assay be included to screen samples for progestogens. The second objective of this study was to compare estradiol rapid ELISAs with a bioassay for anti-androgenicity using mouse testicular cell cultures. The mouse testicular cell testosterone synthesis bioassay to monitor anti-androgenicity of the samples showed no correlation between the ELISA data for estrogens. This study shows that anti-androgenic effects need to be monitored independently because the data for estrogenic compounds cannot be used as a predictor for anti-androgenic effects. This demonstrated the need for the inclusion of a mouse testicular cell testosterone synthesis bioassay to screen for androgenicity and anti-androgenicity of water samples. In summary, due to the different mechanisms of action of EDCs, this study recommended a battery of assays to monitor for EDCs. The battery of assays suggested is: ●Estradiol ELISA as a rapid assay to screen for estrogens. ●Testosterone ELISA as a rapid assay to screen for androgens. ●Progesterone ELISA as a rapid assay to screen for progestogens. ●Mouse testicular cell testosterone synthesis bioassay to screen for androgenicity and anti-androgenicity.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uwc/oai:etd.uwc.ac.za:11394/5107 |
| Date | January 2012 |
| Creators | Baguma, Richard |
| Contributors | Pool, Edmund J. |
| Publisher | University of the Western Cape |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Rights | University of the Western Cape |
Page generated in 0.0026 seconds