Fracking chemicals have been linked to cancer, infertility and birth defects (Reuters) Reuters

Scientists have linked fracking to birth defects and even infertility, claiming it can disrupt human hormones.

A team of researchers claimed fracking, which releases untapped gases from underground rock, uses endocrine-disrupting chemicals, or EDCs. Such chemicals are often found in manufactured products, foodstuffs, air, water and soil and previous research has linked EDC exposure with infertility, cancer and birth defects.

Susan Nagel, of the Missouri School of Medicine, said: "More than 700 chemicals are used in the fracking process, and many of them disturb hormone function. With fracking on the rise, populations may face greater health risks from increased endocrine-disrupting chemical exposure."

The new research is likely to generate further controversy around the subject of fracking, which has received widespread criticism despite the backing of prime minister David Cameron.

The technique, otherwise known as hydraulic fracturing, involves drilling deep underground and releasing a high-pressure cocktail of sand, chemicals and water to crack rocks to release the gas stored inside.

Supporters say it is safe and will allow the UK to become more energy-efficient while creating more jobs. Anti-fracking protesters say the technique will have an adverse effect on the environment and will pose health risks to those living nearby.

The research

The researchers looked at 12 EDCs used in natural gas operations and looked at how they affected male and female reproductive hormones.

They took surface and ground water samples from two sites. One was a drilling-dense area where there had been drilling spills or accidents. The other was from a drilling-sparse area without spills.

Water samples from the drilling-dense site had higher levels of EDC activity that could disrupt the body's response to androgens - a class of hormones that include testosterone and oestrogen.

In comparison, there was little activity in the areas where there was little to no drilling.

Nagel said: "Fracking is exempt from federal regulations to protect water quality, but spills associated with natural gas drilling can contaminate surface, ground and drinking water.

"We found more endocrine-disrupting activity in the water close to drilling locations that had experienced spills than at control sites. This could raise the risk of reproductive, metabolic, neurological and other diseases, especially in children who are exposed to EDCs."