Summary: A new study found that a group of chemicals called photoinitiators, often used in paints, plastics and inks, act like estrogen. In mouse studies, photoinitiators could make breast cancer cells multiply faster. Tamoxifen partly blocked this. That confirms these chemicals mainly do harm through estrogen receptors. Breast cancer is the most common cancer among women. Genes, hormones and things in our surroundings cause it. Many common products contain chemicals that act like estrogen. These include supplements, factory goods, personal care items and even some foods. These estrogen-like chemicals may cause breast cancer and may also help it grow.
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 breast cancer is associated with more than 42,000 female deaths each year in the US1,2.
Even after years of research, the causes of breast cancer are poorly understood. That is because so many things cause it. Researchers know it is strongly tied to age and family history, or genes. But studies also link it to reproductive factors, the hormone estrogen, lifestyle and contact with toxins in our surroundings3.
Figure 1. Risk factors for breast cancer (image source: Sun Y-S, Zhao Z, Yang Z-N, et al. Risk Factors and Preventions of Breast Cancer. Int J Biol Sci. 2017;13(11):1387-1397. doi:10.7150/ijbs.21635)
In recent years, estrogen-like chemicals have drawn huge attention as a risk factor for breast cancer. Studies show that many estrogen sources may raise the risk of breast cancer. These include hormone replacement therapy, plant estrogens (phytoestrogens) and chemicals that copy estrogen. Estrogens may also help breast cancer grow. That is why drugs that block estrogen now play a special role in breast cancer treatment4,5.
Can chemicals in plastics and paint cause breast cancer?
It is well known that estrogen-like chemicals, not just estrogen, may greatly raise the risk of breast cancer. So researchers are hunting for these substances around us. Studies show that many herbal extracts are rich in plant estrogens. Even some dental implants may contain estrogen-like chemicals6,7.
So it is vital to learn more about these hidden, little-known sources of estrogen-like compounds. That can help cut how many people get breast cancer.
In one of the recent studies, researchers found that photoinitiators that are often added to paints, plastics and 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 light. Thus, they have found wide use in the industry.
The new study found that photoinitiators like MTMP, MBB and 1-HCHPK act strongly like estrogen. When researchers added these chemicals to breast cancer cells grown in a lab, the cells grew faster8.
So researchers tested these chemicals in mice that had human breast cancer cells placed in them. All three chemicals made the cancer grow faster over 13 weeks of exposure.
It means that these chemicals may also cause an increase in breast cancer cell growth in women.
To confirm that the cancer grew because the chemicals act like estrogen, researchers first gave the mice tamoxifen. In those mice, breast cancer grew much more slowly when exposed to the chemicals. Tamoxifen is a well-known drug that blocks estrogen. So the test confirmed that the chemicals’ estrogen-like action drove the faster cancer growth.
This study showed how some common, widely used chemicals may copy estrogen. That way, they may cause breast cancer or help it grow.
Frequently asked questions
What chemicals have been linked to breast cancer?
Estrogen and chemicals that copy it are the main concern. A recent study found three photoinitiators used in paints, plastics and inks, called MTMP, MBB and 1-HCHPK, that act strongly like estrogen. They made breast cancer cells grow. Other estrogen-like sources include hormone replacement therapy, plant estrogens in some herbal extracts and even certain dental materials.
What is the biggest cause of breast cancer?
No single factor causes breast cancer. That is why its causes are still poorly understood. The strongest links are age and family history, or genes. Studies also tie it to reproductive factors, the hormone estrogen, lifestyle and contact with toxins around us. Estrogen-like chemicals have drawn major attention because they may both raise the risk and speed up tumor growth.
What are photoinitiators?
Photoinitiators are chemicals added to paints, plastics and inks. When UV light hits them, they release reactive molecules. That is why factories use them so widely. The new study found that several of them also act like estrogen in the body. That makes them one of the hidden, little-known sources of estrogen-like compounds worth knowing about.
How do these chemicals make breast cancer grow?
They act on estrogen receptors. In mice carrying human breast cancer cells, all three photoinitiators made cancer grow faster over 13 weeks of exposure. When mice were first given tamoxifen, a drug that blocks estrogen, the cancer grew much more slowly. That confirmed the chemicals do harm mainly by acting like estrogen.
References
- 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
- Worldwide cancer data | World Cancer Research Fund International. WCRF International. Accessed October 15, 2021. https://www.wcrf.org/dietandcancer/worldwide-cancer-data/
- Sun Y-S, Zhao Z, Yang Z-N, et al. Risk Factors and Preventions of Breast Cancer. Int J Biol Sci. 2017;13(11):1387-1397. doi:10.7150/ijbs.21635
- Russo J, Russo IH. The role of estrogen in the initiation of breast cancer. The Journal of Steroid Biochemistry and Molecular Biology. 2006;102(1):89-96. doi:10.1016/j.jsbmb.2006.09.004
- Yue W, Wang J-P, Li Y, et al. Effects of estrogen on breast cancer development: Role of estrogen receptor independent mechanisms. International Journal of Cancer. 2010;127(8):1748-1757. doi:10.1002/ijc.25207
- Kassi E, Papoutsi Z, Fokialakis N, Messari I, Mitakou S, Moutsatsou P. Greek Plant Extracts Exhibit Selective Estrogen Receptor Modulator (SERM)-like Properties. J Agric Food Chem. 2004;52(23):6956-6961. doi:10.1021/jf0400765
- Schafer TE, Lapp CA, Hanes CM, Lewis DJB. What parents should know about estrogen-like compounds in dental materials. :2.
- 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
Dr. Gurpreet Singh Padda, MD, MBA, MHP
