A new study suggests that parabens, the preservatives widely used in consumer products like shampoos and sunscreens, may increase the risk of breast cancer, Rapid News Network reports.

Parabens have been a focus of researchers for a long time. Earlier studies have revealed that this class of preservatives may be a health concern.

 "Although parabens are known to mimic the growth effects of oestrogens on breast cancer cells, consider their effect too weak to cause harm", said lead investigator Dale Leitman, a gynaecologist and molecular biologist at the University of California Berkeley.

Leitman, Vulpe and their colleagues at the Silent Spring Institute published their findings online Oct. 27 in the journal Environmental Health Perspectives. 

The California Breast Cancer Research Program helped fund this research.

The research was conducted on human breast cancer cells in a lab. Therefore, it is still not clear whether parabens have the same effect in the human body.

Catherine Priestley, Clinical Nurse Specialist at Breast Cancer Care, said: "This is incredibly early research".

For the study, the researchers activated the HER2 receptors in breast cancer cells with a growth factor called heregulin, while exposing the cells to parabens.

The results of the study showed that parabens are more potent at lower doses than previous studies had suggested. The study may cause scientists and regulators to rethink the impacts of parabens on the development of breast cancer, particularly on HER2 and estrogen receptor positive breast cells.

"While this study focused on parabens, it's also possible that the potency of other estrogen mimics have been underestimated by current testing approaches," said co-author Chris Vulpe, a toxicologist formerly at UC Berkeley but now at the Center for Environmental and Human Toxicology at the University of Florida College of Veterinary Medicine.