Environmental toxins affect the body's hormone systems

Marianne Kraugerud's thesis studies the effects of different variants of the environmental toxins PCB and PFC on sheep and on cells grown in the laboratory. Her research on sheep is of comparative interest for humans.

Polychlorinated biphenyls (PCB) and perfluorinated compounds (PFC) are chemicals that only break down naturally to a very small degree and therefore have a strong tendency to accumulate in the environment. While PCBs are known to be environmental pollutants and have not been legally produced since the 1970s, the use of many PFC variants is rapidly increasing in products such as water-resistant clothing and coatings in saucepans and frying pans.

Marianne Kraugerud's thesis shows the effects of PCB 118 and PCB 153, which are two separate PCB variants with different chemical characteristics. In lambs exposed to these substances while in the womb and via their mother's milk, effects were demonstrated both on the formation of egg cells in the ovaries and on the hormones that control the function of the ovaries in female lambs. Kraugerud also found that sheep foetuses that had been exposed to these PCB variants while in the womb had a diminished ability to produce the vital hormone cortisol.

Through laboratory cell cultures, Kraugerud demonstrated that both PCB and PFC can directly affect the production of steroid hormones. Steroid hormones, including for example oestrogen, testosterone and cortisol, are necessary for maintaining the capacity to reproduce, normal development and normal bodily functions in humans and animals. Since PCBs and PFCs are widespread in the environment and can affect the body's hormone systems in a more complex way than previously supposed, Marianne Kraugerud recommends that these effects are emphasised when risk appraisals on these substances are drawn up.

Marianne Kraugerud, veterinary surgeon, presented her doctoral thesis on 21st June 2010 at The Norwegian School of Veterinary Science. The thesis is entitled: "Endocrine disruption by persistent organic pollutants: effect studies using in vivo and in vitro models."