Environment Agency ‘A study of wild roach in English rivers indicates that oestrogenic contaminants continue to occur at levels sufficient to produce a biological response in fish. The results of a study of wild roach in English rivers indicate that oestrogenic contaminants continue to occur at levels sufficient to produce a biological response in fish in rivers. The oestrogenic effects observed – the feminising of male fish (termed intersex) – result from exposure to effluents from wastewater treatment works, which can contain natural and synthetic oestrogens originating from human excretion and the breakdown of industrial detergents.
Previous studies from the 1990s/2000s had shown that oestrogenic (feminising) effects were common in UK roach populations. The new study has revealed that feminisation of males is still occurring at the same sites and remains at similar levels in most locations. However, there are indications that concentrations of oestrogens may be lower than historical levels. This could be associated with water company investments to improve waste water effluent treatment. These findings have implications for the nationwide monitoring and regulating of oestrogenic contaminants to ensure the health of fish populations and other river life.’
Published 30 October 2020