Definition: The measure of chemicals in the environment, including air and water in the outside environment and chemicals in indoor dust and air.
Classification: Tool and technique for human study
People are exposed to environmental chemicals through the air they breathe, the water they drink, the food they eat and the products they intentionally and unintentionally put on their bodies. As a result, choosing which of these multiple aspects of the environment to evaluate for chemical contamination may greatly affect the types of associations drawn between health outcomes and chemical exposures. Trying to understand possible associations between exposures to chemicals early in development and later life disease is even more difficult as the pattern of environmental pollution has been in constant flux over many decades (Weschler, 2009).
During the mid-20th century the use of many pesticides and solvents increased significantly. Following regulatory action banning or limiting production and use of some of these substances, such as PCBs, DDT and PBDEs, exposure levels decreased, often substantially. Other chemicals, including many that did not exist 50 years ago—such as plasticizers, flame retardants and other common additives to products we use daily—have recently increased in usage and presence in our environment.
Environmental monitoring can evaluate the concentration of chemicals both inside and outside. Scientists at the Silent Spring Institute, an independent research institute in Massachusetts, have pioneered methods to collect indoor dust samples. Their analysis of air and dust samples in homes have revealed significant levels of many compounds of concern for breast cancer, including phthalates, alkylphenols, pesticides, flame retardants and many other endocrine-disrupting compounds (EDCs) (Rudel 2003; 2009).
A collection of studies suggest that chemical concentrations tend to be higher indoors and tend to break down more slowly (Goyal, 2009; Rudel, 2003, 2009). Exposures to chemical pollutants in our homes and schools, as well as outdoors, may vary by season or even by day of the week (e.g., weekend vs. weekday), reflecting differences in ventilation and in agricultural, traffic, cleaning and professional/recreational activities (Goyal, 2009; Perrone, 2010; Verschaeve, 2007; Zimmerman, 2008).
Measuring indoor levels of chemicals allows for a significant snapshot of our daily exposure profiles. Measurement of indoor air and especially dust is particularly critical for understanding the environments young children are exposed to (Hwang, 2008) because early-life exposures have profound effects on development of many diseases, including breast cancer, asthma and several neurodevelopmental disorders (Kamel, 2004; Landrigan, 2005; Perrera, 2005; Wigle, 2008). We know that children’s exposures to toxicants in the home may lead to a higher body burden of those chemicals as compared to adults because of differences in children’s ventilation rates, metabolism of toxicants, hand-to-mouth behaviors, and constant contact with floors and other surfaces (Ginsberg, 2008).
Some critical data required for these studies are difficult to obtain because of the way regulatory agencies draw geopolitical boundaries. When direct measures of pollutants in air, water or land is not feasible, often proxies are used, like distance from a known polluting factory, as a predictor of levels of a particular type or mixture of toxic chemicals (Friis, 2011). Environmental monitoring can also be costly.