A chemical which is used to make non-stick coatings for saucepans and as a stain and water repellent for fabrics and carpets has now been connected to adult thyroid disease.

The blood samples of 4,000 US adults were tested by the scientists between 1996 and 2006 for the presence of the chemical perflourooctanoic acid (PFOA). They found that 25 percent of these adults who had the highest levels also had twice the incidence of thyroid problems.

The last 50 years have seen the production of PFOA being used in a wide variety of materials. It is believed to make an entry into the body in the diet or as dust inhaled through the lungs.

Studies done on animals have shown that the chemical can affect the thyroid function, which is very important to maintain the heart rate, regulating body temperature and also supporting other functions of the body.

The researchers, from the University of Exeter, who conducted the study, said that they had displayed a relation between the two but had not proved the casualty.

They said, “Our results highlight the need for further research”.

Other researchers have given skeptical inputs regarding this finding. Professor Ieuan Hughes, from the University of Cambridge and chair of the committee on the toxicity of Chemicals in the Environment, said that the evidence was “tenuous” for the link.