Researchers have identified 921 chemicals thought to increase the risk of breast cancer and say none should be considered "low hazard" until further investigation is done.
The study, published Jan. 10 in Environmental Health Perspectives, found the 921 chemicals "that induce mammary tumors in rodents, stimulate estradiol or progesterone synthesis, or activate the estrogen receptor in vitro".
There were 279 chemicals directly linked to mammary tumors in animals, identified by researchers as "mammary carcinogens" and 642 chemicals were found to stimulate estrogen or progesterone signaling, which is known to increase breast cancer risk.
Of the 921 total, 90% are used in everyday products including medication, food and pesticides, according to the researchers.
"We argue that many of these should not be considered low hazard without investigating their ability to affect the breast, and chemicals with the strongest evidence can be targeted for exposure reduction," they wrote of their findings.
The list should be used to improve treatment and research on the disease globally, they stated.
Editor's note: The research highlighted was sponsored by Silent Spring Institute, a Massachusetts nonprofit that supports the environment and women's health.