Chemical sours mother's milk

Published: Sunday 30 November 2008

Pollutant keeps the iodine in breast milk from babies

a common pollutant called perchlorate may be the reason behind iodine deficiency disorders among children, said a group of us researchers. Infants get their required dose of iodine from breast milk. Theories have linked iodine deficiency among infants to two factors: one, if the mother is undernourished and iodine-deficient, and two, if the baby is unable to absorb iodine from the breast milk. A group of scientists from the University of Texas, usa, found that the second factor is common and linked it to perchlorate.

The chemical is extensively used in making firecrackers, explosives and rocket fuel. Through years of use, it has contaminanted food and water.

To find out if a mother's exposure to the chemical could affect her child's ability to absorb iodine from breast milk, Purnendu K Dasgupta and his team collected samples of milk from 13 mothers and measured the content of iodine and perchlorate in it. They found the level of perchlorate in the breast milk was so high that 12 of 13 infants were not be able to imbibe sufficient iodine from the milk. According to the Institute of Medicine, Washington D C, infants in the age group of 0-6 months should get 110 microgramme (g) of iodine a day. However, due to the presence of perchlorate, some infants receive only 12 per cent of the recommended quantity. Furthermore, while only 21 per cent of the mother's iodine was found to make its way to breast milk, more than 56 per cent of the perchlorate in the mother's body ended up in the milk. The researchers found that the perchlorate level in the breast milk was so high that the infants ingested about 0.3-0.2 g of perchlorate for every kg of their bodyweight a day. This exceeds the safety limits (0.7 g/kg/d) set by the us National Academy of Sciences.

Iodine deficiency inhibits the function of a thyroid gland that secretes the hormone thyroxine. The hormone controls the development of the nervous system in infants and is often blamed to retard mental growth and cause brain damage and growth impairment. The deficiency also decreases survival rates in children. To control the problem, common salt is fortified with iodine in several countries including India.

The effect of perchlorate on the thyroid gland has been well established. It is also used to treat a hyperactive thyroid gland. Chemicals like thiocyanate and nitrate have also been implicated in low iodine uptake. But they do not make their way into breast milk in such large amounts as perchlorate, the researchers said in their study paper to be published in the journal Environmental Science and Technology in November.

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