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Janet Gray, Ph.D.
Janet Gray, Ph.D.

As author of our 2008 and 2010 State of the Evidence reports, Dr. Gray drives the science behind all our work.

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Biomonitoring Pollution in People

To understand the links between chemical exposures and breast cancer, we must be able to trace which chemicals people were exposed to and when. Biomonitoring and comprehensive exposure data are critical pieces in building this understanding.

One of the most significant barriers to understanding the links between exposures to chemicals and breast cancer in humans is our lack of ability to trace what chemicals people were exposed to and when.

Presently, most studies of human populations must rely either on people's memories of their past exposures or on measuring household dust for chemicals of concern. In dust studies, high-powered vacuums collect dust from crevices and hidden places in people's homes to measure chemicals from years past. While dust studies are a recent innovation that has helped increase understanding of chemical exposures, neither dust studies nor human memory is as accurate as actual measures of exposure.


That's where biomonitoring comes in. Biomonitoring is the measurement of chemicals – or their breakdown products – in the body. Chemicals can be measured in urine, blood and saliva with relative ease (Fernandez, 2007). Scientists also sometimes measure the chemicals in the fatty tissue of breasts when this fat is removed during cancer and other surgeries. Measuring chemicals in fat has shown that higher levels of environmental chemicals were found in leaner, post-menopausal women with breast cancer (Ibarluzea, 2004).

Some biomonitoring projects draw from local populations to measure chemicals in women with and without breast cancer in a specific geographic area and to link this to environmental exposures, as well as other factors such as family history, diet, alcohol consumption and body weight.

Biomonitoring projects of larger populations would provide a very powerful tool for drawing links between chemical exposures and breast cancer, as well as other diseases. Having measurements of chemicals in the body at different points in people's lifetimes would greatly enhance researchers' ability to look at early-life exposures and the development of breast cancer later in life (Angerer, 2006).

One important challenge to biomonitoring research is that procedures to measure the levels of many chemicals in human samples do not exist. These tools need to be developed in order to increase the strength of biomonitoring research.

Comprehensive Exposure Data

In our everyday lives, we are exposed to multiple repeated low doses of the same chemical and to mixtures of chemicals, which may act together to increase risk for diseases including breast cancer (Koppe, 2006; Kortenkamp, 2006). We know that low-dose exposures to chemicals that disrupt hormones can have particularly serious health effects (NAS, 2008; Diamanti-Kandarakis, 2009; Fenton, 2006). In addition, many real-life low-dose exposures are continuous or occur throughout the day. For instance, people may be exposed to phthalates, which are found in both plastics and personal care products, during their morning shower from the shower curtain, when using shampoo, conditioner, lotions or soaps with fragrances, and from foods stored in phthalate-containing storage containers. These repeated, low-dose exposures occur for an array of chemicals every day.

Understanding the total exposure to single chemicals and the mix of chemicals people are exposed to every day would provide a missing piece of the puzzle in understanding environmental links to breast cancer.