Household chemical perfluorooctanoic acid linked to thyroid disease

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Household chemical perfluorooctanoic acid linked to thyroid disease

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A **ubiquitous** chemical widely used in the manufacture of non-stick

frying pans is linked to thyroid disease, researchers say.

 

 

A study involving almost 4,000 people in the United States found that

those with the highest levels of man-made perfluorooctanoic acid (PFOA) in

their blood were twice as likely to be diagnosed with thyroid disease or taking

medication compared with those with the lowest levels.

 

 

PFOA is widely used in industry because it excels at repelling heat,

water, grease and stains. Traces of the chemical are found in water, air and

soil throughout the world.

 

 

Researchers from the University of Exeter, who carried out the latest

study, stressed that further research was needed to establish whether the

chemical was a direct cause of illness in humans.

 

 

Previous studies in animals have suggested that high exposure to the

chemical can affect the action of the thyroid gland, located in the neck, which

is responsible for controlling the body’s rate of metabolism through the

release of hormones.

 

 

Tamara Galloway, Professor of Ecotoxicology at Exeter, said that it was

likely that the chemical could be ingested or inhaled from the air or as a

component of household dust and might stay in the bloodstream for about five

days.

 

 

Her team analysed an American database of 3,966 adults, aged 20 and older,

because no figures for blood levels of PFOA are available in Britain. Of

these, 163 women and 46 men reported having current thyroid disease and were

taking medication.

 

 

However, a total of 16 per cent of women with the highest blood levels of

the chemical (above 5.7ng/ml) reported having thyroid disease or were

taking related medication, compared to 8 per cent of those with the lowest

levels. The trend was similar in men, but not said to be statistically

significant because of the low numbers of individuals involved.

 

 

**Our results highlight a real need for further research into the human

health effects of low-level exposures to environmental chemicals like PFOA

that are ubiquitous in the environment and in people*s homes. We need to know

what they are doing,** Professor Galloway said.

 

 

Diane Benford, the head of toxicology of food at the Food Standards

Agency, said: “This type of study investigates associations and cannot

establish

causality. It is important to look at the consistency of the data with the

results of other studies, and with what is known about the toxicity of PFOA

and PFOS, which differ.

 

 

**Studies of workers with higher exposure to these compounds have not

shown consistent evidence of increased risk of thyroid disease, which would be

expected if effects are occurring in the general population. More research

is needed to establish whether this association is causal.**

 

 

Ashley Grossman, Professor of Neuroendocrinology at Queen Mary, University

of London, said that it was also unknown how PFOA might affect the thyroid

gland.

 

 

**Thyroid disease is often caused by the body’s own immune system

attacking the thyroid gland so perhaps this chemical is having some effect on

the

immune system, rather than directly on the thyroid,** he said.

 

 

**We’d need to do a lot more research to verify this link and to

understand how the two are linked. In the meantime it’s important to remember

that

thyroid disease can be successfully treated.**