The effect of chlorination of estrogenic chemicals on the level of serum vitellogenin of Japanese Medaka (oryzias latipes)

Abstract

Mature male medaka were continually exposed to four chemicals, p-n-nonylphenol (p-n-NP), nonylphenol (p-NP), bisphenol-A (BPA) and 17beta-estradiol (E2) to evaluate their estrogenic activities in the laboratory. In order to understand the effect of the chlorination that is applied widely in water and wastewater treatment, the above chemicals were chlorinated and then exposed to mature male medaka. Furthermore, in the case of vitellogenin, a is a female specific protein induced by the exposure to test waters containing the above chemicals after 5 weeks, medaka was returned to uncontaminated tap water to determine whether male medaka have a self recovery function from the effect of estrogenic chemicals. Much greater vitellogenin compared to the background levels were induced in the male medaka by separate exposure to 100 microg/L of p-NP, 1,000 microg/L of BPA and 0.05 microg/L of E2. The levels of vitellogenin increased with increasing exposure periods. The relative potencies of these chemicals descended in the order of E2>>p-NP>BPA. Vitellogenin levels inducible by these chemicals were drastically reduced as a result of the chlorination for 24 hours. However, a moderate increase in hepatocyte somatic index (HSI) meant the hepatic fatness was observed as a result of chlorination. It is not clear at this stage whether or not the formation of chlorination byproducts is responsible for this moderate increase in HSI. The vitellogenin concentration of male medaka exposed to chemicals for 5 weeks decreased gradually after return to the uncontaminated water. However, the vitellogenin concentration did not return to the initial normal levels even after 5 weeks. A clear relationship between the serum vitellogenin concentration and the hepatic vitellogenin concentration was also found. Since quantitative analytical procedures for hepatic vitellogenin are easier than those of the serum vitellogenin, measuring the estrogenic effect using the measurement of vitellogenin in liver is recommended.

Toxicity to early life stages and an estrogenic effect of a bisphenol A metabolite, 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene on the medaka (Oryzias latipes)

“…Sohoni et al (2001) demonstrated that BPA induced VTG synthesis in male fathead minnows (Pimephales promelas) at concentrations of 640 and 1280 Ag/ l after 43 days and 160 Ag/l after 71 days. In medaka, Tabata et al (2003) observed marked increases in the serum VTG concentrations of mature male fish after 5 weeks of exposure to 1000 Ag BPA/l. In addition, Kang et al (2002a) demonstrated that concentrations of hepatic VTG were increased significantly in males of reproductive phase treated with BPA at 3120 Ag/l.…”

Occurrence of endocrine disrupting compounds in water sources of Belo Horizonte Metropolitan Area, Brazil

“…The chlorination of EDCs might result in a reduction of water estrogenicity [44] or its enhancement [45,46], and, since this is a disputed issue, more research is needed in this area.…”

Behaviour of bisphenol A (BPA), 4-nonylphenol (4-NP) and 4-nonylphenol ethoxylates (4-NP1EO, 4-NP2EO) in oxidative water treatment processes

“…Hu et al (2002b), using a yeast two-hybrid system showed that aqueous chlorinated 4-NP solutions elicit anti-estrogenic activities. Tabata et al (2003) ascertained by means of vitellogenin synthesis in male Medaka fish that chlorination using 1.5 mg/l NaClO did not increase the vitellogenin synthesis. On the other hand Requena et al (unpublished, cit.…”