Ohyama, K, F Nagai and Y Tsuchiya 2001. Certain Styrene Oligomers Have Proliferative Activity on MCF-7 Human Breast Tumor Cells and Binding Affinity for Human Estrogen Receptor. Environmental Health Perspectives 109:699-703.

It had been shown previously that styrene compounds migrate into food from disposible styrene lunch boxes (Sakamoto et al. 2000) and styrene instant food containers (Kawamura et al. 1998).

Using two different approaches, this study asked whether the migrating styrene compounds are estrogenic. The results demonstrate that some are estrogenic, with their potency varying among the various dimers and trimers tested on par, roughly, with the estrogenic potency of bisphenol A.

What did they do?
Ohyama et al. performed two laboratory analyses of the estrogenicity of styrene compounds. First, they tested the ability of the compounds to induce proliferation in a cell culture of human breast cancer cells, MCF-7. Second, they tested the binding affinity of the compounds to the human estrogen receptor a (hERa).

The styrene oligomers tested (with abbreviations) were 1,3-diphenyl propane (SD-1), 2,4-diphenyl-1-butene (SD-2), cis-1,2-diphenyl cyclobutane (SD-3), trans-1,2-diphenyl cyclobutane (SD-4), 2,4,6-triphenyl-1-hexene (ST-1), 1a-phenyl-4a-(1´-phenylethyl)tetralin (ST-2), 1a-phenyl-4e-(1´-phenylethyl)tetralin (ST-3), 1e-phenyl-4a-(1´-phenylethyl)tetralin (ST-4), 1e-phenyl-4e-(1´-phenylethyl)tetralin (ST-5), 1e,3e,5a-triphenylcyclohexane (ST-6), and 1e,3e,5e-triphenylcyclohexane (ST-7)

What did they find?

Styrene dimers SD-3 and SD-4 and styrene trimers ST-1, ST-3, ST-4, and ST-5 demonstrated estrogenic activity on MCF-7 cells and binding affinity for hERa.

Styrene trimers ST-1, ST-3, ST-4, and ST-5 had the highest proliferative activities of the compounds tested. The relative potency of these chemicals compared to estradiol was 0.0002-0.0015%, which was comparable with that of bisphenol A.

ST-6 and ST-7 did not appear to bind to hERa. SD-1, SD-2, ST-2, ST-6, and ST-7 had insignificant proliferative activities.

What does it mean?
Some of the styrene compounds leaching into food from styrene containers are estrogenic. Whether they leach in sufficient quantities to cause harm is not known as appropriate tests, particularly with developing embryos and fetuses, have not been carried out.