Cause for Concern
Ecosystems all over the world are now contaminated with a cocktail of man-made chemicals.
CHEM Trust is particularly worried about several potentially hazardous chemicals, especially those that are persistent, bioaccumulative or those which can disrupt hormones.
Persistent chemicals are those which don't break down easily in the environment, and which can therefore last for decades. A chemical is said to ‘bioaccumulate' if it builds up in our bodies or in wildlife. Unfortunately, when a chemical is persistent and bioaccumulative (P&B) it may be passed from mother to baby via the egg, placenta or during suckling.
The hormone disrupting chemicals are very worrying because even at extremely low doses they can disrupt the normal workings of the reproductive, immune, nervous and other hormonally controlled systems. They can do this by mimicking natural hormones or blocking their action, or altering the breakdown or synthesis of the body's own hormones. Sometimes these chemicals are also called endocrine disrupting chemicals or EDCs for short, because it is the endocrine glands which secrete hormones.
Some pesticides and flame retardants are persistent, bioaccumulative or hormone disrupting. Similarly, chemicals with these worrisome properties may be found in many consumer products including certain stain repellents, cosmetics, personal care products and plastics.
There is a growing body of scientific evidence on the adverse impacts of several man-made chemicals on wildlife species. Scientists have shown that many wildlife populations have already been affected by hormone disruptors. The impacts include:
- thyroid dysfunction in birds and fish
- decreased fertility in birds, fish, shellfish and mammals
- decreased hatching success in birds, fish and turtles
- gross birth deformities in birds, fish and turtles
- metabolic abnormalities in birds, fish and mammals
- behavioural abnormalities in birds
- de-masculinisation and feminisation of male fish, birds and mammals
- de-feminisation and masculinisation of female fish and birds
- and compromised immune systems in birds and mammals
- The connection between effects in wildlife and the likely effects in humans are also being noted.
Day in, day out, terrestrial, freshwater and marine species are exposed to a toxic cocktail of many different man-made compounds and the concern is that such chemicals can under mine future generations of wildlife (and humans). There is not one ocean or continent from the tropics to the once-pristine polar regions that is not contaminated.
Ecosystems and wildlife everywhere including seals, whales, fish, polar bears, migratory birds and many other species have been seriously affected.
For example, research carried out on fish, in many UK estuaries indicates that there is significant feminisation of the males in these populations. The male fish should have sperm in their testes but many have egg material there instead.
The researchers concluded that the chemicals responsible for these endocrine disrupting effects come from sewage works and from industrial discharges.
Other interesting research has been carried out on the polar bears in northern Norway where "pseudohermaphrodites" have been reported, and it seems that several females have a small penis.
More analysis of the data is needed, but toxic chemicals may pose a threat to the future of polar bears, particularly because many persistent chemicals undergo a process of global re-distillation and can be found at high levels in the polar regions. Furthermore, mammals that are top predators are exposed to particularly high levels via the food chain and in early life via the placenta and suckling.
The pages in this section illustrate some examples of the known or suspected effects of chemical contaminants in wildlife.
CHEM Trust’s report Effects of Pollutants on the Reproductive Health of Male Vertebrate Wildlife - Males Under Threat by Gwynne Lyons.
A shortened version of this report is available in German
This report shows that male fish, amphibians, reptiles, birds and mammals have been harmed by chemicals in the environment. Widespread feminisation of male vertebrate wildlife is highlighted. These findings add to mounting worries about the role of hormone-disrupting or so-called ‘gender-bending' chemicals in the environment, and the implications for human health.
Persistent organic pollutants and indicators of otter health: other factors at play? highlights serious concerns for the health of otters in the UK.
Otters are one of our best loved species and research indicates that they may not be in the best of reproductive health. This raises the question as to whether modern chemicals, particularly endocrine disrupting chemicals (EDCs - hormone disruptors), could be to blame.