Prenatal exposure to chemicals used in fracking for oil or natural-gas operations may affect sperm count later in life, a new study performed on mice suggests.

The study demonstrated that 23 out of 24 investigated fracking chemicals can act as endocrine-disrupting chemicals (EDCs), which disrupt and mimic hormones in the body. Typical environmental doses of the EDCs may pose a risk to men's fertility, particularly for those living close to fracking sites, the researchers say.

Senior author on the paper Dr Susan Nagel from the University of Missouri told the Huffington Post: 'Bottom line, hormones work at very low concentrations naturally. It does not take a huge amount of chemical to disrupt the endocrine system.'

The study, published in the journal Endocrinology, found that adding various concentrations of common chemicals used in oil and natural-gas production to the drinking water of pregnant mice resulted in male pups with lower sperm counts and larger testes. Changes to the heart and, at high concentrations, increased body weight were also observed.

The researchers demonstrated that 90 percent of tested fracking chemicals disrupted the functioning of oestrogens and androgens, including testosterone. Another sex hormone, progesterone, and the stress hormone glucocorticoid were affected by 40 percent of the identified fracking chemicals, while 30 percent of the compounds altered the function of thyroid hormone, which is involved in metabolic regulation.

Curiously, the effect of chemical exposure was not always related to the dose and, in several cases, smaller concentrations resulted in greater changes than higher doses. Dr Nagel said: 'It is clear EDCs used in fracking can act alone or in combination with other chemicals to interfere with the body's hormone function. These mixture interactions are complex and challenging to predict.'

Hydraulic fracking is a method of extracting oil or natural gas by injecting large amounts of water mixed with chemicals and sand into the ground, but many environmental groups are opposed to it.

Living close to fracking sites has been associated with reproductive and developmental problems, such as an increased risk of premature birth and congenital heart defects. The extent to which fracking chemicals can contaminate the water supply is unclear, however, and a recent report by the US Environmental Protection Agency found 'no evidence of widespread water contamination'.

Dr Rob Westaway, who is senior research fellow in Systems Power and Energy at the University of Glasgow, commented that the UK shale gas industry is subject to the same standard safety regulations as other industries. He told the Independent: 'As a result of ... misinformation [from environmental groups], they have scared the living daylights out of millions of people regarding shale gas, for no good reason.'

Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.