New report: US regulatory agencies have been underestimating the risk of harm from chemicals like phthalates
Posted December 18, 2008 in Health and the Environment
Today an expert group of scientists issued a strongly worded report that verifies what most of us already knew - we live in a toxic soup of chemicals that we accumulate by breathing contaminated air, eating contaminated food, drinking contaminated water and some we absorb by applying them to our skin in the form of personal care products. We are even exposed to chemicals in the womb. All of us are exposed to multiple chemicals at the same time and throughout our lives.
This is the reality of our industrialized world but it hasn't been the way our federal government has been thinking about chemical exposures when they are making regulatory decisions about "acceptable" levels of exposure.
Instead, when setting a chemical safety standard, federal agencies such as the EPA, rely on laboratory studies that use genetically identical animals under controlled laboratory conditions and with exposure to one chemical at a time.
Some chemicals, such as pesticides, have been considered as a group because of their structural similarities, but no safety assessments have ever considered groups of chemicals that are not structurally similar or don't work through the same pathway but do cause the same outcome (such as reproductive or neurodevelopmental harm). For example, lead, mercury and PCBs through different pathways are all known to cause a loss of IQ points, but no federal agency has based a "acceptable" level of exposure on the cumulative effects of all these chemicals. Instead, each chemical has been considered on an individual basis.
Today's report from the National Academy of Sciences asserts that continuing this one chemical at a time approach is too narrow and underestimates the risk of harm. The report focuses on a group of chemicals called phthalates but its recommendations could be applied to many health outcomes and groups of chemicals.
Phthalates are found in everyday products - cosmetics and personal care products, building materials such as vinyl flooring, automobile interiors, artificial leather, air fresheners, and in children's toys made from PVC (for example, a rubber ducky).
Phthalates are under scrutiny because certain ones are known to be hormone disruptors and cause a reduction in levels of the male hormone, testosterone. When testosterone levels are reduced during critical periods, such as during development of the male genitals, abnormalities occur. At least in the lab animals, these abnormalities are permanent changes that impact fertility later in life.
The report strongly recommends to EPA that they should consider all phthalates and other male developmental reproductive toxins when determining an "acceptable" level of exposure, also called a reference dose. This number is important because it can drive drinking water or clean up standards and will also be used by other Agencies when making regulatory decisions.
In the case of phthalates, both the FDA and CPSC (Consumer Product Safety Commission) have regulatory authority. The FDA has approved a number of phthalates as food additives and the CPSC is overseeing an upcoming safety assessment on the use of phthalates in toys. Although this report was requested and directed to EPA, the recommendations should be heeded by both FDA and CPSC when doing their evaluations of phthalates.
You can read excerpts of the report online.
It is a long document and I've summarized some of the conclusions:
- "Recent data have shown widespread human exposure to multiple phthalates from a multitude of sources. Studies have also identified high-exposure groups that may be more vulnerable to the effects of phthalates and their metabolites. Those groups potentially include the fetus and child, whose exposure and metabolism may differ from those of the adult and impart differences in risk."
- "... the pathways for the critical action of androgens during fetal life are highly conserved and operate in humans as they do in experimental animals. It is biologically plausible that adverse reproductive outcomes could occur if specific phthalates or mixtures of phthalates reach the developing human fetus at the appropriate concentration and in the appropriate developmental window."
- "There is good evidence that combinations of phthalates and of other antiandrogens produce combined effects at doses that when administered alone do not have significant effects."
- "The current practice of restricting cumulative risk assessment to structurally or mechanistically related chemicals ignores the important fact that different chemical exposures may result in the same common adverse outcomes."
- "....emphasize the necessity of conducting cumulative risk assessment of phthalates and other antiandrogens to assess risks posed by exposure to mixtures of these compounds. Assessments based solely on the effects of single phthalates and other antiandrogens may lead to considerable underestimation of risks to the developing fetus."
- "Many of the chemical profiles in IRIS (EPA chemical's database) need to be updated; the information is no longer relevant or accurate. The phthalate profiles available in IRIS illustrate that point."
- "...some consideration should be given to restructuring IRIS so that its process for identifying chemicals for review includes and sets priorities among chemical mixtures, as appropriate, and facilitates cumulative risk assessment conducted by using common adverse outcomes."