Endocrine disrupting chemicals in freshwater and marine water
Toxicant default guideline values for protecting aquatic ecosystems
Extracted from Section 8.3.7 ‘Detailed descriptions of chemicals’ of the ANZECC & ARMCANZ (2000) guidelines.
The default guideline values (previously known as ‘trigger values’) and associated information in this technical brief should be used in accordance with the detailed guidance provided in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality.
Description of chemical
Recently there have been increasing reports on the disrupting effects that chemicals released into the environment may be having on the normal endocrine functioning in a variety of aquatic organisms and terrestrial wildlife (Colborn et al. 1996, USEPA 1997b, OECD 1997a). Disruption to the endocrine system affects hormone production and distribution, ultimately impinging on basic life functions such as reproduction and development of the reproductive system, growth, maintenance of the body’s internal environment, and production utilisation and storage of energy (Wilson & Foster 1985). Adverse effects observed have included: abnormal thyroid function and development in fish and birds; decreased fertility and hatching success; either demasculisation and feminisation or defeminisation and masculinisation of various species; decreased offspring survival; and alteration of immune and behavioural function (USEPA 1997b).
These effects have been attributed to various chemicals, including some persistent organochlorines such as PCBs, DDT, dioxin and some pesticides (USEPA 1997b, Toppari et al. 1995). A spill in 1980 of dicofol contaminated with DDT metabolites was associated with severe effects on alligators and turtles in Lake Apopka in Florida, particularly on production and hatching, juvenile survival and normal development of reproductive systems (Guillette 1995, USEPA 1997b). Tributyltin (TBT) is well known for causing imposex (development of male characteristics) in female gastropods (Ellis & Pattisina 1990). Alkylphenols (e.g. nonylphenol and octylphenol) which are breakdown products of alkylphenol polyethoxylates used as industrial surfactants and bases for household products, have been linked with estrogenic effects in fish (Jobling et al. 1996). Harries et al. (1997) detected estrogenic effects in four of five UK rivers tested downstream of sewage treatment plants and wool scouring mills and related these to alkylphenols. Studies downstream of sewage plants in USA have produced similar results (Folmar et al. 1996), and also demonstrated some depression of serum testosterone levels in carp exposed to agricultural runoff. Recent studies (Desbrow et al. 1997) have indicated that the most widespread substances causing estrogenic effects from sewage treatment plants are both natural and synthetic oestrogenic hormones often in only very small quantities. Other chemicals which may cause endocrine disruption, but with little evidence to date in the aquatic environment, are bisphenol A (a plastic monomer), phthalates (Toppari et al. 1995), as well as cadmium, lead and mercury (OECD 1997b). There is also evidence of masculinisation of fish and disruption of reproduction downstream of pulp and paper mills (USEPA 1997b), which may be due to phytosterols released from the wood.
Often the same disruptive effect may be induced additively by mixtures of small quantities of different chemicals (conversely, mixtures of PCBs often have little estrogenic activity due to the mixture of compounds with opposing effects) (McLachlan & Arnold 1996). Secondly, it is thought that such adverse effects may be caused by a single, relatively small dose during a window of vulnerability for the foetus and effects may not appear until later (Center for the Study of Environmental Endocrine Effects 1995).
The current knowledge on endocrine disrupting chemicals is insufficient to make recommendations on water quality guidelines at present. Outcomes from the considerable international activity on endocrine disruptors (OECD 1997a,b, USEPA 1997b) will need to feed into future revisions of the Guidelines. Current challenges include assessing the likelihood of adverse effects on populations and communities, as well as establishing cause-effect relationships for effects observed in the field (USEPA 1997b), improving exposure assessment and assessing the effects of mixtures (Kavlock et al. 1996).
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