Hormones are the body's chemical messengers, regulating everything from growth and metabolism to reproduction and behaviour. Endocrine-disrupting chemicals (EDCs) interfere with this delicate system — and marine life is paying the price.
What Are Endocrine Disruptors?
EDCs are substances that can mimic, block, or alter the body's hormones. They include synthetic oestrogens from contraceptive pills, bisphenol A (BPA) from plastics, phthalates from personal care products, and certain pesticides.
Even at incredibly low concentrations — parts per trillion — EDCs can have profound biological effects. This is because hormonal systems are designed to respond to minute chemical signals.
Effects on Marine Life
The evidence is alarming. Male fish downstream of wastewater treatment plants have been found producing eggs — a condition called intersex, caused by synthetic oestrogens in the water. In some rivers, up to 100% of male roach show signs of feminisation.
Sea turtles' sex is determined by temperature during egg incubation, but EDCs can override this, skewing sex ratios. Molluscs exposed to tributyltin (an anti-fouling paint chemical) develop imposex — females growing male reproductive organs.
Marine mammals at the top of the food chain accumulate the highest concentrations through biomagnification. Polar bears, seals, and dolphins show some of the highest EDC levels of any animals on Earth.
The Cocktail Effect
In the real world, organisms aren't exposed to a single EDC — they encounter complex mixtures. Research shows these "cocktails" can produce effects greater than the sum of their parts, making risk assessment extremely challenging.
What's the CONTRAST Project Doing?
CONTRAST is developing new tools to detect and assess EDCs in marine environments, including advanced biomarker techniques and in silico (computer-based) modelling. The goal is to understand not just individual chemicals, but how real-world mixtures affect marine ecosystems.
Taking Action
Support bans on harmful chemicals, choose products free from BPA and phthalates, and dispose of pharmaceuticals at designated collection points rather than flushing them.
This article is part of the CONTRAST project, funded by the European Union under Horizon Europe. Views expressed are those of the author(s) only.