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Research Rebuttal: Gynecomastia & Essential Oils

Posted: March 5, 2007

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Answer: A review of the literature associated with estrogenic activity of phthalates and/or premature breast development (thelarche) revealed that premature breast development in very young girls (< 8 years) is known particularly in Puerto Rico (Bongiovanni 1983). Colón et al. (2000) found that young Puerto Rican girls that had premature breast development had significantly high levels of dimethyl, diethyl, dibutyl and di-2-ethylhexyl phthalates in their serum as well as the metabolite mono-2-ethylhexyl phthalate. Furthermore, the authors showed that the phthalates were endocrine-disrupting chemicals.

Moore (2000) examined the published data on the estrogenic potential oil phthalate esters and concluded that the in vitro studies performed were not relevant to humans or the environment. A note in the report by Moore did show that MCF-7 cells (the same cells used by Henley et al. 2007) did have the capacity to metabolize phthalate esters.

Okubo et al. (2003) found that, of the commonly used and encountered phthalates, some were found in an in vitro to possess estrogenic activity, while others were found to be anti-estrogenic. This finding was supported by Takeuchi et al. (2005). McKee (2004) criticized the findings of Colón et al. (2000) noting that there might well have been an artificial contamination of the serum samples with vinyl laboratory equipment. He also stated that as phthalates are metabolized in the human body rapidly and in vitro studies of the mono-phthalate metabolites are not active under in vitro conditions, he doubted the validity of the Colón et al. (2000) study.

An excellent review of the effects of phthalates on human health has been published (Hauser and Calafat 2005). In this review, the authors cite a study by Zacharewski et al. (1998) in which the phthalates were not found to be estrogenic under either in vitro conditions or in in vivo studies. As a result, it is highly unlikely that phthalates are responsible for any of the changes and activities observed and determined.

Question 8: Do many plant isolates possess estrogenic activity and what is their effect on humans?