The Endrocrine Disruptor Debate

Contributed by The Acheson Group

The Acheson Group, LLC (TAG), led by Dr. David Acheson, is a strategic consulting firm for food and beverage companies and those providing technical support to the food industry.

The controversy on endocrine disruptors, in particular Bisphenol A (BPA), is one of science and politics. From a scientific standpoint, the issues are similar to nanomaterials (link to previous blog), where the question is how to evaluate these chemicals using effective, scientific experimental design. The second component of the discussion relates to FDA’s current assessment that BPA is safe at low levels.

What are Endocrine Disruptors?

Endocrine disruptors are a category of chemicals that can interfere with the human endocrine system. Endocrine disruptors mimic or block hormones and can disrupt the way the body normally functions. Any system in the body that is controlled by hormones, such as the pituitary gland, thyroid and reproductive organs, could be adversely impacted by endocrine disruptors.

What are examples as they relate to food and food packaging?

In a piece developed for consumers, the National Institute of Environmental Health and Sciences identifies examples of endocrine disruptors that are associated with foods, including bisphenol A (BPA) and Di(2-ethylhexyl) phthalate (DEHP) in food packaging and phytoestrogens, such as genistein and diadzein, which can be found in soy-based products.

The Poster Child for Endocrine Disruptors: BPA

Perhaps the best chemical to use as a case study around the science and politics of endocrine disruptors is BPA. This particular chemical is a carbon-based synthetic compound. It is used to make hard, clear plastic known as polycarbonate, which has been used in many consumer products, including reusable water bottles. BPA is also found in epoxy resins, which act as a protective lining on the inside of metal-based food and beverage cans.

BPA has been shown to exhibit hormone-like properties at high dosage levels—orders of magnitude higher than the exposure through food containers. However, the continued exposure, even at low levels, raises concern for its suitability in food containers. In a literature review by Rochester in 2013, there were 91 studies linking BPA to human health, 53 that were published within the last year. This review outlines associations between BPA exposure and adverse perinatal, childhood, and adult health outcomes, including reproductive and developmental effects, metabolic disease, and other health effects. The author does note that “while it is difficult to make causal links with epidemiological studies, the growing human literature correlating environmental BPA exposure to adverse effects in humans … provides increasing support that environmental BPA exposure can be harmful to humans, especially in regards to behavioral and other effects in children.”

Another review identified the debate over the existence of effective scientific design as a component of the controversy. Areas that have been questioned include:

• dose response curves
• mechanisms of low-dose effects
• importance of considering critical periods of exposure such as children

It also identified the issues that divide scientists in this field of research, namely:

1. mechanisms of BPA action
2. levels of human exposure
3. routes of human exposure
4. pharmacokinetic models of BPA metabolism or what happens to BPA in the body
5. effects of BPA on exposed animals
6. links between BPA and cancer

Perhaps the best description of the debate was offered by FDA itself, which stated, “Overall, the current literature cannot yet be fully interpreted for biological or experimental consistency or for relevance to human health. Part of the difficulty for evaluating consistency lies in reconciling findings of different studies that use different experimental designs and different specific behavioral tests to measure the same dimension of behavior.” So, why does the FDA still allow the use of BPA?

What are the Regulators Saying?

The uses of BPA are subject to premarket approval by FDA as indirect food additives or food contact substances. The original approvals were issued under FDA’s food additive regulations and date from the 1960s. Currently, the FDA’s National Center for Toxicological Research is working closely with the National Toxicology Program to carry out in-depth studies to answer key questions and clarify the uncertainties about BPA risk. Here are some actions they are taking:

• FDA is taking steps to reduce human exposure to BPA in the food supply. These steps include:

• supporting the industry’s actions to stop producing BPA-containing baby bottles and infant feeding cups for the U.S. market

• facilitating the development of alternatives to BPA for the linings of infant formula cans

• supporting efforts to replace BPA or minimize BPA levels in other food can linings

• FDA is supporting a shift to a more robust regulatory framework for oversight of BPA
• FDA is seeking further public comment and external input on the science surrounding BPA

In July 2013, FDA banned the use of BPA in baby bottles, sippy cups, and infant formula packaging on the grounds of abandonment. This was solely based on a determination of abandonment, meaning that FDA recognized that the industry no longer uses BPA in these products. The ban was not due to safety concerns.

The European Union also has a ban on the use of BPA in infant feeding bottles. The European Food Safety Authority (EFSA) has a draft opinion on BPA and are delaying the adoption of their opinion about the possible risk of BPA from April to November of this year. This delay is to ensure they can complete ongoing BPA work at the European and national level. The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) of the UK Food Standards Agency (FSA) recently agreed with the EFSA current opinion and will consider if action is necessary when the EFSA issues the final report.

Regulatory agencies responsible for food safety in Canada, Japan and Australia have all reached the same conclusion: there is no risk from use in packaging. The Development and Reproductive Toxicant Identification Committee (DARTIC) of the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) determined that BPA should not be listed on California’s Proposition 65. Given the breadth of chemicals on the Prop 65 list, the exclusion of BPA is significant.

Future of BPA and Possibly an Indication for other Endocrine Disruptors

As was discussed, the controversy on endocrine disruptors, in particular Bisphenol A (BPA), is one of science and politics. Since it has been identified by the FDA in particular that not all the science on BPA is equal, does all the available literature make the cut for a thorough BPA risk assessment? Science is the underpinning of regulatory decisions and more science is becoming available. As previously stated, there have been 53 studies published in the last year or so, so it seems science is being put first. The question can still be asked – is BPA safe? Or are the methods to collect the data such that we still can’t answer that question? 

References

Rochester JR. Bisphenol A and human health: a review of the literature. Reprod Toxicol. 2013 Dec; 42:132-55.

Vandenberg LN1, Maffini MV, Sonnenschein C, Rubin BS, Soto AM. Bisphenol-A and the great divide: a review of controversies in the field of endocrine disruption. Endocr Rev. 2009 Feb; 30(1):75-95.

National Institute of Environmental Health and Sciences. Endocrine Disruptor. Accessed April 18, 2014. http://www.niehs.nih.gov/health/materials/endocrine_disruptors_508.pdf

Food and Drug Administration. “Bisphenol A (BPA): Use in Food Contact Application.” Accessed March 12, 2014 http://www.fda.gov/newsevents/publichealthfocus/ucm064437.htm