Summary: Breast cancer is the most common cancer among women. It is caused by specific genetic, hormonal, and environmental factors. Many commonly used products, supplements, industrial goods, goods of personal use, and even some food products contain estrogen-like chemicals. This estrogen-like substance may cause breast cancer and may also promote its proliferation. The new study found that chemicals belonging to the class photoinitiators, frequently used in paints, plastics, inks, also possess estrogen-like properties. In a study in mice models, photoinitiators could increase the proliferation of breast cancer cells. Moreover, tamoxifen partially blocked their effects, thus confirming that these chemicals primarily cause harm due to their effect on estrogen receptors.
Keywords:breast cancer, estrogen, photoinitiators, cancer risk
Breast cancer is the most prevalent cancer among females globally. Each year around 3 million are diagnosed with it. It also considerably contributes to female mortality. Even worse, its annual incidence rate is increasing. In the US, about 255 000 women are diagnosed with it, and more breast cancer is associated with more than 42 000 female deaths each year in the US1,2.
Despite years of research, factors that cause breast cancer are poorly understood. It is because numerous factors cause it. Thus, researchers know that it has a high association with age and family history or genes.
However, studies also show its association with reproductive factors, hormone estrogen, lifestyle, and exposure to environmental toxins3.
In recent years, estrogen-like chemicals have received massive attention as a risk factor for breast cancer. Studies show that various sources of estrogens like hormone replacement therapy, phytoestrogens, chemical imitating properties of estrogens may increase the risk of breast cancer. Not only that, but estrogens may also promote the growth of breast cancer. Thus, drugs that block the activity of estrogens now have a special place in breast cancer treatment4,5.
Commonly added chemicals to plastics and paint may cause breast cancer
Since it is well-known that not only estrogens but estrogen-like chemicals may also considerably increase the risk of breast cancer, researchers are actively looking for such substances in the environment. Studies show that many herbal extracts are rich in phytoestrogens. Even some dental implants may contain estrogen-like chemicals6,7.
It means that knowing more about these hidden or lesser-known sources of estrogen-like compounds is highly essential to reduce the incidence and prevalence of breast cancer.
In one of the recent studies, researchers found that photoinitiators that are often added to paints, plastics, inks may also increase the risk of breast cancer8. These compounds have some unique properties, like the release of reactive molecules when exposed to UV lights. Thus they have found wide use in the industry.
The new study found that photoinitiators like MTMP, MBB, and 1-HCHPK have high estrogen-like activity. Thus, when researchers added these chemicals to breast cancer cells cultured in a lab, these chemicals promoted their growth8.
Thus, researchers decided to test the effect of these chemicals in animal models, using mice with planted human breast cancer cells. They found that all these three tested molecules increased cancer growth on 13 weeks of exposure.
It means that these chemicals may also cause an increase in breast cancer cells growth in women.
To further confirm their theory that this growth in breast cancer cells was due to the estrogen-like activity of the chemicals, researchers pretreated lab mice with tamoxifen. They found that tamoxifen pretreated mice had much slower breast cancer growth when exposed to these chemicals. Tamoxifen is a well-known drug that can block the activity of estrogen. Thus, the experiment confirmed that the estrogen-like activity of these chemicals was responsible for greater breast cancer growth.
This study demonstrated how some of the common and widely used chemicals might also imitate estrogen and thus may cause or promote breast cancer growth.
1. CDCBreastCancer. Basic Information About Breast Cancer. Centers for Disease Control and Prevention. Published September 21, 2021. Accessed October 15, 2021. https://www.cdc.gov/cancer/breast/basic_info/index.htm
2. Worldwide cancer data | World Cancer Research Fund International. WCRF International. Accessed October 15, 2021. https://www.wcrf.org/dietandcancer/worldwide-cancer-data/
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7. Schafer TE, Lapp CA, Hanes CM, Lewis DJB. What parents should know about estrogen-like compounds in dental materials. :2.
8. Kawasaki Y, Sendo T. Three photoinitiators induce breast tumor growth in mouse xenografts with MCF-7 breast cancer cells. Curr Res Toxicol. 2021;2:322-328. doi:10.1016/j.crtox.2021.08.004