ABERDEEN, Scotland, September 10, 2012 ( – Scientists at the University of Aberdeen studying sheep maintained on pastures fertilized with sewage sludge (treated waste derived from human sewage processing plants) found a high incidence of abnormalities in the animals.  The abnormalities are being attributed to the presence of man-made hormones, particularly as those found in the contraceptive pill, in the treated waste.

Professor Paul Fowler and Dr Stewart Rhind said exposure to the chemicals affected the structure or function of testes, ovaries, uteri, parts of the brain, and thyroid and adrenal glands of sheep foetuses. In adult sheep changes in bone structure, the testes and offspring behavior were observed.


The researchers explained that man-made chemicals known to be endocrine disruptors, found in such things as electrical equipment, building materials, plastics, adhesives, paints and vehicle exhaust, have long been considered a health hazard. However the synthetic hormones found in contraceptive pills, known as progestins, which mimic progesterone, either alone or combined with estrogen, and excreted in human waste pose a greater problem because they are not removed or destroyed by sewage treatment and find their way into the food chain.

“These chemicals are in our air, soil and water. Some are fat soluble and may accumulate in our bodies while others are water soluble and end up passing through us and being flushed down our toilets, entering our environment where they may affect other animals or enter our food chain re-exposing humans,” said Dr Rhind at the British Science Festival ( last week.

Professor Fowler added, “Many of the changes we see are very subtle and not apparent in the living animal; nevertheless, they may be associated with disruptions of many different physiological systems and increased incidences of diseases and reproductive deficiencies such as those that have been reported in a variety of species, including humans. Embryos, foetuses and young animals appear to be particularly vulnerable.

“It’s 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.”

Research into the fertility of sheep exposed to endocrine disruptors in the environment by Dr. Michelle Bellingham of the University of Glasgow found that abnormalities that could result in low sperm counts were found in the testes of 42% of the animals, which led her to suggest that the rise in the use of in-vitro fertilization in humans, particularly as a result of low sperm counts, is due to exposure to these chemicals in the environment.

The Aberdeen researchers remarked that, “We are using our sewage sheep studies as a tool to investigate the impact on physiological systems of long-term exposure, to low concentrations of mixtures of chemicals because in the real world that is what happens.”

“One solution to the problems that these chemicals pose,” they point out, “might be to simply stop using them.

“So what we must do is attempt to identify the most critical disruptors and their impacts and we are beginning to do that in Aberdeen with our sewage sludge studies. We believe there should be a gradual reduction in the use of disruptors identified as being particularly problematic.”

More ominously, the scientists warn that, “If we do nothing, endocrine disruptors may not only impact on human health but all the ecosystems including those on which we depend – if we compromise soil productivity and sustainability of our agricultural systems or cause imbalance in marine and freshwater ecosystems through damage to populations of top predators, ultimately, we threaten our own survival.”