Lyon, France: Exposing a developing female sheep fetus to low doses of chemicals commonly present in the environment can disturb the development of the ovary, a scientist told the 23rd annual conference of the European Society of Human Reproduction and Embryology today (Wednesday 4 July). Dr. Paul Fowler, of the University of Aberdeen, Scotland, UK, said that this research would help to establish the importance of the effect of environmental chemicals for fertility.
Over recent decades there has been a dramatic increase in the production of industrial and agricultural chemicals and heavy metals, and this has coincided with widespread reports of breeding problems in wild animals. Fertility also appears to be declining among humans and there has also been a rise in reproductive defects observed in newborn babies.
Until now, most studies have looked at a short-lived exposure to high doses of single compounds, and have usually done so in mice and rats. Dr. Fowler and his colleagues decided to study the effect of long-term, low-level exposure to a cocktail of chemicals and heavy metals in an animal which has a long pregnancy, therefore better replicating the situation in the human.
Our real life model exposed developing sheep fetuses by pasturing their mothers on fields fertilised with either inorganic fertiliser, the control group, or, in the case of the treatment group, with digested human sewage sludge, before and during pregnancy, said Dr. Fowler.
We examined the ovaries from the fetuses at day 110 of gestation, the equivalent of week 27 in a human pregnancy, and found that the ovaries from the fetuses where the mother was grazing the sewage sludge fields contained fewer eggs and also a number of protein abnormalities. These differences could have implications for problems such as cancer in later life.
The scientists hope that their Wellcome Trust-funded study will help to pinpoint the stages of pregnancy at
Contact: Mary Rice
European Society for Human Reproduction and Embryology