LONDON — Women who drink organic milk while pregnant or breastfeeding could be putting their babies at risk, according to a new study by scientists in the UK.

Scientists at the University of Reading in England published research Tuesday that states the reduced levels of iodine in organic and UHT milk is harmful for babies.

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In the research, published in the journal Food Chemistry, the scientists assert that the amount of iodine found in organic and UHT milk was a third lower than that found in regular milk.

The World Health Organization recommends that pregnant women eat foods that are rich in iodine because of the role it plays in the healthy development of the baby's brain and nervous system while in the womb. It says that iodine deficiency is one of the leading causes of impaired cognitive development in children.

The researchers warned that the number of people buying organic milk has increased because of its perceived health benefits.

“Organic and UHT milk is not bad for you, and drinking all types of milk has numerous health benefits. But to get the same amount of iodine as in a pint of conventional pasteurised milk, you would need to drink around an extra half-pint of organic or UHT milk," said Professor Ian Givens from the University of Reading in a release accompanying the study.

“Iodine deficiency ought to be a health problem from the past. But unless this situation is carefully monitored, we risk sleepwalking into a new health crisis in the 21st century," he said.

The UK's dairy industry hit back at the study, saying that it didn't reflect changes in dairy farming.

“The fact that organic cows historically do not receive iodine in feed may explain why iodine levels have in the past been lower in organic milk," Dairy UK's chief executive, Dr. Judith Bryans, said in a statement.

“At the end of 2014, the industry resumed the practice of enriching feed with iodine and recent testing carried out in January 2015 on a representative number of milk samples found no significant difference in iodine levels between organic and conventional milk.”

In the UK, milk is the largest source of iodine in diets. The National Health Service (NHS) says that dairy products, particularly cow's milk, are a good source of iodine for pregnant and breastfeeding women, recommending they consume 250 micrograms of iodine a day. Oily fish is another source of iodine for pregnant women.