Low-dose Exposures
Two decades of research indicate that very low-dose exposures to toxic chemicals can have profound health effects. This counters the long-held belief that “the dose makes the poison” – a rationale that underlies much chemical regulation, including the use of various chemicals in cosmetics (i). The inaccurate assumption that very small amounts of toxic chemicals are safe allows for the continued use of toxic chemicals in personal care products (ii).
There are at least three key problems with this assumption. First, this assumes that low doses are truly safe, which may not be the case. Research on laboratory animals, cell cultures and wildlife suggests that in some cases low-dose exposures may have more profound effects than higher exposures (iii). Second, this assumption of safety at low doses overlooks the fact that many of the toxic chemicals that appear in cosmetics and personal care products tend to show up in several products an average person uses daily, and that many of these chemicals show up in other consumer products as well (iv). As a result, what seem like small exposures add up to larger doses.
Finally, a long-standing approach to chemical regulation looks at chemicals one at a time. However, daily life exposes individuals to a multitude of various ingredients. For instance, an Environmental Working Group report shows that women use 12 cosmetic products with 168 unique ingredients each day and men use 6 products with an average of 85 ingredients (v). These ingredients, in combination with exposures from other consumer products and pollutants in the air and water, add up to a phenomenal array of combined exposures, in effect adding up to hundreds of exposures every day (vi).
Research indicates that, in many cases, these exposures add up and work in combination to affect health in ways that may be more profound than single exposures. Taking in multiple chemicals can have an additive effect, whereby multiple small exposures add up to a lot (2+3=5), or a synergistic effect, whereby multiple exposures increase the toxic effects of one another (2+3=10) (vii). For instance, several studies have found that combinations of various chemicals with estrogenic properties may have additive (viii) or synergistic effects (ix).
In addition, the timing of exposure may moderate the effects of low doses, so that low doses at certain points in development – prenatally, during puberty, etc. – may have stronger or qualitatively different effects on health (x).
More Information
For more information about how small doses of chemicals impact our long-term health, visit The Endocrine Disruption Exchange.
i Gray, J (2008). State of the Evidence: The Connection between Breast Cancer and the Environment. San Francisco, CA: Breast Cancer Fund.
ii Environmental Working Group (2004). Exposures Add Up – Survey Results. Available online http://www.cosmeticsdatabase.com/research/exposures/php. Accessed August 19, 2008.
iii Gray, J (2008). State of the Evidence: The Connection between Breast Cancer and the Environment. San Francisco, CA: Breast Cancer Fund.
iv Environmental Working Group (2004). Exposures Add Up – Survey Results. Available online http://www.cosmeticsdatabase.com/research/exposures/php. Accessed August 19, 2008.
v Environmental Working Group (2004). Exposures Add Up – Survey Results. Available online http://www.cosmeticsdatabase.com/research/exposures/php. Accessed August 19, 2008.
vi Centers for Disease Control and Prevention (CDC) (2003). Second National Report on Human Exposure to Environmental Chemicals. Available online at http://www.cdc.gov/exposurereport/. Accessed August 19, 2008.
vii Gray, J (2008). State of the Evidence: The Connection between Breast Cancer and the Environment. San Francisco, CA: Breast Cancer Fund.
viii Ramamoorthy K, Wang F, Chen IC, Safe S, Norris JD, McDonnell DP, Gaido KW, Bocchinfuso WP, Korach KS (1997). Potency of combined estrogenic pesticides. Science 275: 405-6.
Foster WG, Younglai EV, Boutross- Tadross O, Hughes CL, Wade MG (2004). Mammary gland morphology in Sprague-Dawley rats following treatment with an organochlorine mixture in utero and neonatal genistein. Toxicological Sciences 77: 91-100.
ix Xie L, Thrippleton K, Irwin MA, Siemering GS, Mekebri A, Crane D, Berry K, Schlenk D (2005). Evaluation of estrogenic activities of aquatic herbicides and surfactants using a rainbow trout vitellogenin assay. Toxicological Sciences 77: 91-100.
Kortenkamp A (2006). Breast cancer, oestrogens and environmental pollutants: a re-evaluation from a mixture perspective. International Journal of Andrology 29: 193-198.
x Gray, J (2008). State of the Evidence: The Connection between Breast Cancer and the Environment. San Francisco, CA: Breast Cancer Fund.
