New healthy mothers are almost always recommended to breastfeed their babies for the initial few months. However, a study by Harvard University researchers suggests that the accumulation of potentially toxic chemicals in human breast milk might actually prove dangerous to babies.

According to the scientists, a class of industrial chemicals called perfluorinated alkylate substances, or PFASs, can easily get accumulated in breast milk and 'build up' to an alarming amount in babies who are breastfed. PFASs are unregulated chemicals that are used in the production of paints, waterproof clothing, lubricants, food packaging and stain proof textiles.

“We knew that small amounts of PFASs (could) occur in breast milk, but our serial blood analyses now show a build-up in infants the longer they are breastfed,” said Professor Philippe Grandjean of the Harvard’s Chan School of Public Health.

“We are concerned that these pollutants are transferred to the next generation at a very vulnerable age.”

Grandjean further said that industries made a serious mistake by not considering the regulation of potentially harmful chemicals that could be excreted through breast milk. The study -- complete details of which have been published in the journal Environmental Science & Technology -- showed that breast milk is a major source of PFAS exposure in infants.

During the study, the researchers took a note of PFAS levels in the bloodstreams of 81 expecting mothers. In addition, the team also assessed the level of the PFAS in babies born to the subject mothers at different intervals -- at the time of birth, after 11 months, 18 months and at the end of five years.

The research team found that in infants who were exclusively breastfed, the levels of PFAS increased by 25 percent each month. In some of the cases, the PFAS level in the children soon exceeded the PFAS levels in their mothers.

A study conducted in the recent past claimed that PFASs can also cause cancer. In another series of experiments, researchers found PFASs to interfere with the reproductive and immune functioning of the lab animals.