Sunscreen Lotions May Cause Breast Cancer
Sunscreen lotions may have the potential to cause breast cancer in women, according to a study by Michigan State University researchers.
The common sunscreen ingredient benzophenone-3, also known as oxybenzone or BP-3, can play a role in the development of mammary gland tumours. The five-year study, funded by the Breast Cancer and the Environment Research Program housed in the National Institute for Environmental Health Sciences (NIEHS) and the National Cancer Institute (NCI), was recently published in Oncotarget.
"Our set of results suggest caution in using BP-3 and the need to dig deeper to understand what it can do in mammary glands and tumorigenesis,” said Richard Schwartz, professor in the Department of Microbiology and Molecular Genetics, who has been researching the interaction of diet and cancer cell growth and proliferation for more than 12 years.“This is the first published result that makes a convincing case that BP-3 can change cancer outcomes."
The researchers landed on BP-3, a ubiquitous and easily absorbed chemical. A recent report in the Journal of the American Medical Association found that after just one heavy application of sunscreen, blood levels of BP-3 exceeded the Federal Drug Administration’s guidance for chemicals at a threshold of toxicological concern, and the Centers for Disease Control found BP-3 in 98 percent of adult urine samples.
BP-3 is also a suspected endocrine disrupting chemical (EDC), substances that interfere with hormonally regulated processes the body uses for a wide range of functions, including mammary gland development.
Using a mouse model where the mammary glands lacked a gene often mutated in human breast cancer as a proxy for women growing from puberty into adulthood, the scientists put the mice under three distinct dietary regimes: a lifelong low-fat diet, a high-fat diet during puberty switching to a low-fat diet during reproductive years and vice versa.
The experiment split mice on these three diets into two groups. One of these groups was fed BP-3 daily at a dose equivalent to a heavy application of sunscreen on a beach day.
Over the course of a year and a half of treatment, the researchers collected tumors from the mice and found robust evidence for the adverse effects of diet and BP-3 on breast cancer development.