A new study found that a group of chemicals commonly used in cosmetics and other personal-care products may stimulate the growth of breast cancer cells at doses considerably lower than previously believed.
The study was conducted on human breast cancer cells growing in lab dishes. It is unclear whether these chemicals act the same in the human body.
However, parabens have been shown in previous lab and animal studies to mimic the activity of the hormone estrogen. When estrogen binds to estrogen receptors it causes cell to multiply which increases breast cancer risk in women.
Parabens are a type of chemical preservative and are found in a wide array of consumer products, including shampoos, body lotions and sunscreens.
Parabens can also activate the same pathway as estrogen, however previous studies found that this is a weak process. Because they are believed to be weak they are assumed to be safe compounds.
However, previous studies only analyzed parabens by themselves.
The new study focused on the effects of parabens when mixed with one additional compound, a growth factor called heregulin. Heregulin has also been linked to breast cancer cell growth.
Researchers analyzed how well the cells grew when they were exposed to both parabens and heregulin. This analysis was compared with how the cells grew when exposed only to parabens. Researchers found that when they added heregulin, they could decrease the level of parabens by 100 times and the cancer cells would still multiply father than those without heregulin.
This discovery shows that when heregulin is added, the parabens are 100 times more potent at stimulated cancer cell growth. This increased potency may affect humans.
More studies are needed to determine how safe the parabens are. They cannot be tested by themselves but must be tested with other chemicals that stimulate cell proliferation.
The study raises concerns about the safe levels of parabens used in cosmetic products, however more research is required before a decision can be made about the safety of parabens.