On March 3, 2014 the magazine Mother Jones published “A Frightening Field Guide to Common Plastics” online. Journalist Alex Park compiled information about estrogenicity of different plastics’ migrates, based on a 2011 publication in Environmental Health Perspectives (Yang et al. 2011).
In their 2011 publication, Chun Yang, George Bittner and colleagues measured plastic migrates in the estrogen-sensitive MCF-7 in vitro test, a breast cancer cell line assay. While MCF-7 is suitable for detecting estrogen-mimicking chemicals at very low concentrations, it is also highly prone to so called “false positive” results from sample contamination. In the study performed by Yang and colleagues, the authors failed to include several essential controls; in addition, the samples assayed were from retail and may have contained estrogenic substances from other sources than the packaging itself. Therefore, the findings from this study need to be treated with caution. Well-designed research is necessary to tease out how various potential sources of estrogenic activity in packaged foods, including food contact materials, sample contamination, and the food itself, contribute to the overall estrogenicity measured by Yang and colleagues.
As a consequence, the “field guide to common plastics” is not based on robust scientific understanding; for example, it lists styrene, the monomer of polystyrene, as an estrogenic substance. While there is evidence for styrene oligomers (dimers and trimers) to show estrogenic activity, styrene itself has not found to be estrogenic. Other issues of concern relating to plastic food packaging, but not mentioned in the “field guide”, are the unidentified non-intentionally added substances (NIAS, FPF report) present in all plastics, or the lack of adequate toxicity testing data for many indirect food additives used in plastics manufacture (Neltner et al. 2013).
Mother Jones (March 3, 2014). A Frightening Field Guide to Common Plastics.
Neltner et al. (2013) “Data gaps in toxicity testing of chemicals allowed in food in the United States.” Reproductive Toxicology 42:85–94.
Yang et al. (2011) “Most plastic products release estrogenic chemicals: a potential health problem that can be solved.” Environmental Health Perspectives 119(7):989-996.