Sex and Sewage
By Kathryn Lougheed
Man-made chemicals found in water, soil and air may have long-term effects on human and animal health, warn scientists presenting at the British Science Festival. Professor Paul Fowler and Dr Stewart Rhind of the University of Aberdeen believe that this problem might be as significant a threat to humanity as climate change.
Endocrine disrupters are chemicals that can interfere with biological systems, even at extremely low concentrations. They are found everywhere - in plastics, household cleaners, electrical equipment, pharmaceutical drugs, cosmetics and traffic fumes, to name a few sources. Short of moving to the middle of nowhere and giving up all modern comforts, it is impossible to avoid being constantly exposed to a low level mixture of endocrine disrupters.
Fowler and Rhind suggest that these chemicals are partly responsible for the consistent decrease in fertility seen in some parts of the world as well as increases in the incidences of diseases including certain cancers. Because they are still developing, unborn children are likely to be most vulnerable. This is exactly what the researchers have seen in sheep grazing on pasture treated with sewage sludge.
Many a horrible thing we don't like to think about ends up in waste treatment plants - industrial waste and road runoff, for example, in addition to sewage. Treated water is returned to the water system still containing endocrine disrupters while sewage pellets are commonly used as a fertiliser, meaning that the chemicals get into both water and land-based ecosystems.
Fowler's and Rhind's sewage-exposed sheep showed changes in their reproductive organs, brains, and endocrine glands. For example, foetal ovaries contained fewer potential eggs, and testes had fewer of the cells that go on to become sperm. They also had fewer of those responsible for making testosterone.
If the endocrine disrupters found in the human environment have the same effects on us, it could help explain some modern fertility problems, as well as increased levels of premature menopause and early puberty.
If this problem is not tackled, the researchers believe we could be jeopardising our own futures. We depend on healthy ecosystems for survival and, if the results in sheep are anything to go by, a huge number of other living organisms from bacteria right up to the top predators will be affected by chemicals released into the environment.
But dealing with this situation is not as simple as stopping use all together. "Life would be impossible - you would be back to the Stone Age, or before, and that's not going to happen," says Rhind. Instead, he believes we need to find a balance that means we don't need to give up plastics and air travel, but can find a way to reduce exposure to the most harmful endocrine disrupters.