Health risks of common chemicals highlighted

OUR PLANET is awash with man-made chemical residues arising from a range of household products, from kitchen cleaners to plastic coatings. They could, however, have as big an impact on ecosystems and future human health as that expected to arise from climate change.

Most of the chemicals involved are considered completely safe or at least not toxic, according to Dr Stewart Rhind of the James Hutton Institute in Scotland.

However, because there are so many products, from fire retardants and adhesives to paints and even residual chemicals from the pharmaceutical drugs we take, they have the potential to interact in unexpected ways.

Those of greatest concern were known as “endocrine disruptor compounds”, he said. These are substances that mimic the actions in the body normally triggered by the release of human hormones, particularly sex hormones.

There are perhaps 100,000 chemicals used in everyday products and they find their way into the environment.

“The one thing all of the chemicals have in common is to be able to disturb the endocrine system.”

The effects were being induced at very low concentrations so they did not have a toxic effect but a low-level long-term effect. “They affect all animal species from bacteria all the way up to humans,” Dr Rhind said.

“The issue that we face is the very complex mixture of these chemicals in the environment,” said Prof Paul Fowler of the University of Aberdeen. He and Dr Rhind were speaking at the Festival of Science at the university.

They described a long-running trial set up in 1997 in which sheep were grazed on a field spread with dried sewage solids, the material left in sewage treatment works after processing. These make excellent fertilisers but tend to concentrate chemical residues dumped into the sewerage system.

“Our main interest is in the effect of the chemicals on the growing [sheep] foetus,” said Prof Fowler. The growing embryo and foetus were particularly susceptible to mutations and alterations due to the residue substances. If sheep were affected, so too could humans.

“It is notable that incidences of breast and testicular cancer and of fertility problems in humans are increasing, while populations of animal groups as diverse as amphibians and honey bees are in decline,” Prof Fowler said.

In the trials they have found that lambs have altered testes with fewer sperm-producing cells and, in females, the ovaries have fewer eggs. The implications go far beyond these effects, however. So diffuse and persistent are these substances that they have the potential to alter ecosystems.

“If we perturb the soil ecology, the bacteria, fungi and worms, we may alter the fertility of our soils. It really affects everything; these chemicals get everywhere,” Dr Rhind said. “If we screw up the environment, we may be damaging our own future.”

They say if nothing is done, human health may also be harmed, also soil and oceans. Behaviour must be changed and manufacturers influenced by choosing products free of the potentially most harmful chemicals.