Endocrine disruptors are chemicals that stop the production or block the transmission of hormones in the body, often interfering with bodily processes and development. Both natural and synthetic endocrine disruptors pollute the marine environment. They can cause abnormalities in reproduction, the immune system, sexual characteristics, growth and respiration in marine animals.

There are a large range of chemicals with endocrine disrupting properties. These include naturally occurring hormones such as oestrogen, and synthetic chemicals like pesticides, fungicides and insecticides, drugs such as oral contraceptives, and industrial chemicals like tributyltin (TBT), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and dioxins.

Of these, the damaging effects of TBT, once widely used in antifouling paint on boats, are perhaps the most widely documented. TBT is known to cause imposex (female growth of male sex organs) and intersex (hermaphrodite condition) in marine invertebrates such as dog whelks, oysters and mussels. TBT will leach from boat hulls treated with TBT based anti-foulant paint, and the devastating effect on commercial shell fisheries in the 1980's led to a European ban on TBT use for boats less that 25 metres length in 1987. A total European ban will come into effect on 1^st January 2008.

Research on endocrine disruptors has also concentrated on the effects of synthetic oestrogens discharged into the sewer system as a result of the widespread use of oral contraceptives.

In humans, reduced sperm counts in men have been attributed to oestrogen contamination in drinking water, and its feminising effects on fish, both in the laboratory and in fresh water environments, have been well documented.

In the UK, alarm bells over oestrogen pollution were first rung by researchers who reported hermaphrodite fish in the settlement lagoons of sewage treatment works. Further research found that discharged sewage effluent contained high levels of oestrogen, and several UK estuaries including the Mersey, Tee and Tyne and were severely contaminated. The effect on coastal and offshore marine life is still largely unknown.

What MCS wants:

• improvement and better regulation of dry-dock and wash down facilities to prevent TBT contamination of coastal waters from vessels stripped of anti-foulant paint.
• further research on anti-foulant paints that do not contain heavy metals
• investment in the new generation of water based paints developed to replace the solvent borne barriercoats, such as copper co-polymers, that contain high concentrations of volatile organic compounds (VOCs). 
• Research and investment in endocrine stripping technology for sewage treatment plants.
• for the Government to develop a endocrine disruptor monitoring strategy for marine and coastal waters as part of its implementation of the new European Water Framework Directive.

More information is available in the Defra report ‘Endocrine Disruption In The Marine Environment (EDMAR) published in 2002. www.defra.gov.uk/environment/chemicals/hormone/pdf/edmar_final.pdf

What you can do:

• Join the Marine Conservation Society today and support our campaigns to protect the marine environment for wildlife and future generations.
• Avoid burning manufactured items such as plastics, rubber and furniture on bonfires.
• Reduce your  use of toxic chemicals such as fly sprays, detergents and weed killers.
• Small boat owners visit The Green Blue website  http://www.thegreenblue.org.uk/ for advice on eco-friendly antifoulants.
• Report suspected chemical pollution incidents on the Environment Agency hotline: 0800 80 70 60