New study shows estrogen from various sources is impacting fish in UK rivers
By Summit Voice
SUMMIT COUNTY — More research from the UK is showing that remnant chemicals from birth control pills, hormone therapy drugs, plastics manufacturing and other sources — collectively known to contain endocrine disrupting chemicals — are bending the gender of fish.
The new study, led by the universities of Exeter and Brunel, shows those chemicals can have a significant impact on the ability of fish to breed in UK Rivers.
“This is the first time we’ve seen firm evidence that the intersex fish, males that have been feminised by EDCs, have a reduced ability to breed,” said Charles Tyler, from the University of Exeter‘s Biosciences department. “Clearly this raises concerns about the implications on the future for wild fish populations living in UK rivers, but there’s also much wider issues raised by these findings. Some of the effects seen in fish could occur in other animals too as hormone systems are quite similar across all vertebrates.
“EDCs have been tentatively linked with human health impacts too, including, falling sperm counts and cardio-vascular disease. These findings remain more controversial,” Prof Tyler added. “In contrast, we have shown, unequivocally that environmental estrogens alter sexual development in fish and now, through this study, that this can impact on their ability to breed.”
The endocrine disrupters have been seeping into rivers through the sewage system for decades and have an observed effect on fish, altering male biology to make them more female – hence the ‘gender bending’ reputation of these chemicals.
Until now, there has been no solid evidence to show the long-term impact of this effect on fish in the wild – but the new research focusing on wild roach in two UK rivers (Bourne and Arun) has provided new evidence.
Two large-scale breeding studies assessed the ability of fish to breed by using a genetic technique to match offspring produced to their parents. It was found that intersex fish – those that had their sexuality compromised by EDCs and which contain both male (sperm) and female (eggs) sex cells – had their reproductive performance reduced by up to 76 percent.
“Fish still share many biological links with humans and the fact that their reproduction has the potential to be affected by EDCs is certainly a cause for concern. From a risk assessment point of view, these results are very significant.”