Wastewater treatment plant effluent alters pituitary gland gonadotropin mRNA levels in juvenile coho salmon (Oncorhynchus kisutch).

It is well known that endocrine disrupting compounds (EDCs) present in wastewater treatment plant (WWTP) effluents interfere with reproduction in fish, including altered gonad development and induction of vitellogenin (Vtg), a female-specific egg yolk protein precursor produced in the liver. As a result, studies have focused on the effects of EDC exposure on the gonad and liver. However, impacts of environmental EDC exposure at higher levels of the hypothalamic-pituitary-gonad axis are less well understood. The pituitary gonadotropins, follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh) are involved in all aspects of gonad development and are subject to feedback from gonadal steroids making them a likely target of endocrine disruption. In this study, the effects of WWTP effluent exposure on pituitary gonadotropin mRNA expression were investigated to assess the utility of Lh beta-subunit (lhb) as a biomarker of estrogen exposure in juvenile coho salmon (Oncorhynchus kisutch). First, a controlled 72-h exposure to 17α-ethynylestradiol (EE2) and 17ß-trenbolone (TREN) was performed to evaluate the response of juvenile coho salmon to EDC exposure. Second, juvenile coho salmon were exposed to 0, 20 or 100% effluent from eight WWTPs from the Puget Sound, WA region for 72h. Juvenile coho salmon exposed to 2 and 10ng EE2L(-1) had 17-fold and 215-fold higher lhb mRNA levels relative to control fish. Hepatic vtg mRNA levels were dramatically increased 6670-fold, but only in response to 10ng EE2L(-1) and Fsh beta-subunit (fshb) mRNA levels were not altered by any of the treatments. In the WWTP effluent exposures, lhb mRNA levels were significantly elevated in fish exposed to five of the WWTP effluents. In contrast, transcript levels of vtg were not affected by any of the WWTP effluent exposures. Mean levels of natural and synthetic estrogens in fish bile were consistent with pituitary lhb expression, suggesting that the observed lhb induction may be due to estrogenic activity of the WWTP effluents. These results suggest that lhb gene expression may be a sensitive index of acute exposure to estrogenic chemicals in juvenile coho salmon. Further work is needed to determine the kinetics and specificity of lhb induction to evaluate its utility as a potential indicator of estrogen exposure in immature fish.

Molecular comparison of Mycobacterium avium isolates from clinical and environmental sources.

We collected Mycobacterium avium isolates from clinical and drinking-water sources and compared isolates among themselves and to each other using molecular methods. Four clinical isolates were related to water isolates. Groups of indistinguishable clinical isolates were identified. The groups of identical clinical isolates suggest a common source of exposure.

Persistence of nontuberculous mycobacteria in a drinking water system after addition of filtration treatment.

There is evidence that drinking water may be a source of infections with pathogenic nontuberculous mycobacteria (NTM) in humans. One method by which NTM are believed to enter drinking water distribution systems is by their intracellular colonization of protozoa. Our goal was to determine whether we could detect a reduction in the prevalence of NTM recovered from an unfiltered surface drinking water system after the addition of ozonation and filtration treatment and to characterize NTM isolates by using molecular methods. We sampled water from two initially unfiltered surface drinking water treatment plants over a 29-month period. One plant received the addition of filtration and ozonation after 6 months of sampling. Sample sites included those at treatment plant effluents, distributed water, and cold water taps (point-of-use [POU] sites) in public or commercial buildings located within each distribution system. NTM were recovered from 27% of the sites. POU sites yielded the majority of NTM, with >50% recovery despite the addition of ozonation and filtration. Closely related electrophoretic groups of Mycobacterium avium were found to persist at POU sites for up to 26 months. Water collected from POU cold water outlets was persistently colonized with NTM despite the addition of ozonation and filtration to a drinking water system. This suggests that cold water POU outlets need to be considered as a potential source of chronic human exposure to NTM.