Alert as gender bending sewage alters lambs' sex; Fears for human

0 Comments | Sunday Herald, The, Nov 21, 2004 | by Rob Edwards

NEW warnings that a tiny amount of pollution can alter the gender of sheep have sparked fears that it could also affect human health.

Scientists at the government's Macaulay Land Use Research Institute in Aberdeen have discovered that male lambs exposed to low- level environmental contamination start behaving like females.

This has worrying implications, they warn. The toxic soup of industrial chemicals in the air may disrupt human hormones and make people more vulnerable to disease.

"If these results are confirmed by further studies, I believe humans have reason to be concerned about exposure to mixtures of pollutants, even at the very low concentrations present in the environment," said Dr Stewart Rhind, one of the institute's leading scientists.

"These results, combined with many other studies, suggest that exposure to low levels of a mixture of pollutants could result in subtle alterations to human and animal behaviour, and immune and reproductive function."

People are exposed to small concentrations of thousands of synthetic chemical compounds in the air, in water and in food. Many of them are classed as gender-benders, or "endocrine disrupters", because they can interfere with natural hormone cycles in the body.

In the past some of these have been linked to lowered sperm counts in men and the "feminisation" of fish found near sewage outfalls. They include ingredients from contraceptive pills, dioxins from combustion, the banned industrial compounds PCBs (polychlorinated biphenyls), and fire retardants called PBDEs (polybrominated diphenyl ethers). There are also groups of chemicals like the alkyl phenols, used in detergents, and the phthalates used to soften plastic for baby toys. Heavy metals such as cadmium, lead, chromium and mercury could also be implicated.

The study, conducted by Rhind and colleague Hans Erhard at the publicly funded institute, provides the first evidence that the low levels of contamination in the environment are affecting animals.

In a five-year study on a research farm at Hartwood in North Lanarkshire, they reared 80 lambs. Half of them, along with their mothers, were fed on pasture fertilised by processed sewage sludge containing residual levels of contamination.

The other half, and their mothers, were raised on pasture to which only uncontaminated fertiliser was applied. When the lambs were five months old, they were taken to a research station in Kincardineshire, and put through a series of tests.

There Rhind and Erhard found a striking alteration in the behaviour of the male lambs exposed to the contamination. They were much more curious about unusual objects than the uncontaminated male lambs.

The time they spent sniffing three toys, two containers of lavender and mint and a bottle brush was recorded. Over five minutes, contaminated males sniffed for an average of 140 seconds, while the uncontaminated males sniffed for only 84 seconds.

The tendency to explore strange objects is much more common among female than male lambs. Rhind and Erhard concluded that the pollution had caused the lambs to lose some of their male attributes.

The scientists say the sewage sludge was applied as liquid and pellets in accordance with the rules laid down by the regulatory authorities. Sludge is made from treated domestic and industrial wastes, and contains low levels of thousands of contaminants.

Rhind and Erhard stress that the contamination does not pose any "direct danger" to anyone who eats lamb. But they are worried it could have "adverse implications" for the reproductive and immune systems of humans, wildlife and domestic animals.

Their study was funded by the Scottish Executive's environment and rural affairs department and appears in the scientific journal Science Of The Total Environment.

Although environmental groups approve of sewage sludge as a fertiliser, they are concerned about the "subtle contamination" of the land.

"Even extremely low levels of contamination by a range of chemicals, which individually should give no cause for concern, adds up to a real effect in these sheep," said Dr Richard Dixon, head of policy at WWF Scotland. "This low-level cocktail effect is also likely to be affecting humans It is part of the global chemical experiment being conducted on us all."

Dixon called on the water industry to redouble efforts to cut contamination of sludge from factories, offices and homes. "The farming industry needs to look again at the levels of sludge being applied and the rules about when sheep can return to treated fields," he said.

A spokeswoman for Scottish Water, which produces sewage sludge, said: "Recycling sewage sludge to land is recognised across Europe as the best practicable environmental option in most circumstances.

"The water industry has worked hard to reduce the input of pollutants to the sewerage network, and this will continue as new regulatory regimes provide more powers to control pollution at source."

The Scottish Environment Protection Agency (Sepa), which is responsible for regulating the application of sewage sludge to land, responded cautiously.