Arsenic (As) exposure is associated with a variety of negative health effects. It appears to contribute to cardiovascular and lung diseases, type 2 diabetes, problems with brain development, and skin, bladder, and lung cancers. However, arsenic does not appear to be a major risk factor for breast cancer.
In fact, arsenic exposure has been reported to reduce breast cancer risk in some populations. However, a new study has reported that exposure to arsenic in the womb alters both the prepubertal and postpubertal development of the mammary gland in ways that could increase breast cancer risk.
Types of arsenic
Arsenic molecules are characterized as either organic (containing carbon) or inorganic (without any carbon atoms). Inorganic arsenic is linked to negative health effects. Arsenite (various inorganic arsenic compounds containing oxygen) has been shown to be estrogenic, with estradiol-like effects that activate the estrogen receptor. Arsenic trioxide (As2O3) is used as a cancer treatment and has been shown to induce apoptosis (programmed cell death) in breast cancer cells.
Sources of arsenic exposure
Arsenic is an element found at low levels in soil, water, and air. It is often found in drinking-water. Some man-made chemicals, including several pesticides, contain arsenic. However, food is the source of most human exposure. Plants take up arsenic from the soil and incorporate the element as they grow (it cannot be washed off or cooked out, for the most part). While inorganic arsenic is widespread in vegetables, fruit, grains and seafood, rice and apple juice are two common foods that can be concentrated sources, depending on their geographic origin. Unlike cadmium, arsenic does not build up in the body and is eliminated within days. Consumer protections against arsenic in food are weak.
Latest research finds prenatal exposure influences breast development
The study referenced at the beginning of this news article was designed to investigate the effects of prenatal exposure to arsenic in an animal model of mammary gland development. While early life exposure to estrogen and estrogenic compounds contribute to the risk of early puberty, thereby increasing breast cancer risk, the results of the present study demonstrate that exposure to arsenic also influences mammary gland development well before puberty.
In the study, in utero exposure to arsenite resulted in a greater number of mammosphere-forming cells, as well as increased branching, density, and number of epithelial cells in the prepubertal mammary gland. Prenatal exposure also resulted in the overexpression of estrogen receptor alpha (ERα) in the postpubertal gland. This overexpression was a result of an increased and altered response of ERα to estradiol.
The authors conclude that, in addition to advancing the onset of puberty, exposure to arsenite in the womb alters both the prepubertal and postpubertal development of the mammary gland and might increase the risk of developing breast cancer.
Please see our articles on the prenatal period and infancy for more information.
Selected breast cancer studies
Arsenic methylation capacity is associated with breast cancer in northern Mexico
López-Carrillo L, Hernández-Ramírez RU, Gandolfi AJ, Ornelas-Aguirre JM, Torres-Sánchez L, Cebrian ME. Arsenic methylation capacity is associated with breast cancer in northern Mexico. Toxicology and Applied Pharmacology. Elsevier BV; 2014; 280:53-59 10.1016/j.taap.2014.07.013
Arsenic, Organic Foods, and Brown Rice Syrup
Jackson BP, Taylor VF, Karagas MR, Punshon T, Cottingham KL. Arsenic, Organic Foods, and Brown Rice Syrup. Environmental Health Perspectives. Environmental Health Perspectives; 2012; 120:623-626 10.1289/ehp.1104619
Elevated Levels of Metals and Organic Pollutants in Fish and Clams in the Cape Fear River Watershed
Mallin MA, McIver MR, Fulton M, Wirth E. Elevated Levels of Metals and Organic Pollutants in Fish and Clams in the Cape Fear River Watershed. Archives of Environmental Contamination and Toxicology. Springer Science and Business Media LLC; 2011; 61:461-471 10.1007/s00244-010-9633-z
Arsenic speciation in turnip as affected by application of chicken manure bearing roxarsone and its metabolites
Yao L, Li G, Dang Z, He Z, Zhou C, Yang B. Arsenic speciation in turnip as affected by application of chicken manure bearing roxarsone and its metabolites. Plant and Soil. Springer Science and Business Media LLC; 2008; 316:117-124 10.1007/s11104-008-9764-4
Effects of Various Cooking Processes on the Concentrations of Arsenic, Cadmium, Mercury, and Lead in Foods
Perelló G, Martí-Cid R, Llobet JM, Domingo JL. Effects of Various Cooking Processes on the Concentrations of Arsenic, Cadmium, Mercury, and Lead in Foods. Journal of Agricultural and Food Chemistry. American Chemical Society (ACS); 2008; 56:11262-11269 10.1021/jf802411q
Arsenic in Rice: II. Arsenic Speciation in USA Grain and Implications for Human Health
Zavala YJ, Gerads R, Gürleyük H, Duxbury JM. Arsenic in Rice: II. Arsenic Speciation in USA Grain and Implications for Human Health. Environmental Science & Technology. American Chemical Society (ACS); 2008; 42:3861-3866 10.1021/es702748q
Identification of arsenic-binding proteins in human breast cancer cells
Zhang X, Yang F, Shim J, Kirk KL, Anderson DE, Chen X. Identification of arsenic-binding proteins in human breast cancer cells. Cancer Letters. Elsevier BV; 2007; 255:95-106 10.1016/j.canlet.2007.03.025