How much do man-made chemicals affect our health?
David Fullbrook says calls are growing to study and regulate substances that disrupt hormones
An urgent hunt is under way across Scandinavia for the culprit causing testicular cancer rates 10 times the global mean. Scientists suspect a man-made substance or interaction between substances which disrupts hormones, possibly before birth.
Endocrine disruptors are thought to be a factor in birth defects, autism, breast cancer and declines in sperm quality. There have been several cases of medicines disrupting hormones in women, harming their children.
While laboratories have demonstrated endocrine disruption on human hormones, and damage observed in wild animals, confirming causality in humans is difficult for several reasons. One, the effect must be disentangled from stressors such as poor diet, smoking and environmental factors like smog. Two, a substance might only cause disruption after interacting with other substances in the environment and body. Three, only 800 out of 143,000, and rising, industrial chemicals have been assessed for endocrine disruptor potential.
Problems are widespread. This month, for example, Aquatic Biology published findings by Wen Rushu and colleagues of sexual changes in mosquitofish due to estrogenic contaminated water in the Pearl River while a team led by Zeng Qiang reported findings in Ecotoxicology and Environmental Safety suggesting estrogenic chemicals in tap water at a treatment plant in Wuhan .
Moreover, some disruptors persist indefinitely. The full effects may only be clear to future generations facing accumulating and perhaps irreversible consequences. Not surprisingly, prudential calls for comprehensive control are growing louder.
"The time has come for political action," declared Asa Westlund last week after her fellow European parliamentarians overwhelmingly approved a resolution demanding the European Commission strengthen precautionary action, increase research and tighten monitoring of imports. In February, the World Health Organisation and UN Environment Programme issued a landmark report calling for more research and testing.
These are steps on a path probably leading to comprehensive international conventions and strong domestic regulation. The problem is global and sufficiently complex that anything less is unlikely to secure sustainability in the management of these man-made substances.
As challenging, perhaps more so, is finding substitutes for unsafe substances and clean-up methods for the damage already done. Nascent green chemistry has a lot of work ahead.
David Fullbrook is a sustainability economist