Scientific Data Regarding Phthalate Exposure

What is the connection to human breast cancer?  

Recent research shows that several phthalates increase cellular growth in human breast cancer cell lines (Kim).  These phthalates are butyl benzyl phthalate (BBP), di-n-butyl phthalate (DBP), and diethylhexyl phthalate (DEHP).  They also found that these three phthalates decrease the effect of tamoxifen in the same breast cancer cell line.

A group of Japanese scientists found that DEHP and BBP stimulated human breast cancer cells to grow (Okubo).  They suppressed the effect of the phthalates by adding a chemical that inhibits estrogen, providing more evidence that DEHP and BBP act like estrogen.

We know that excess exposure to estrogen causes breast cancer because estrogen stimulates the growth of breast cancer cells.  We need more research on phthalates before a direct connection to breast cancer risk can be established, but we should proceed with caution.

What about human male reproductive system changes? 

Swan and her research team showed that pregnant women’s exposure to phthalates causes genital abnormalities in their male infants.  A recent study reported decreased serum levels of the male hormone testosterone among baby boys exposed to phthalates in their mother's breast milk (Main).

Online resources

www.pollutioninpeople.org/toxics/phthalates Reducing exposure and reading labels

www.environmentcalifornia.org/environmental-health/stop-toxic-toys/phthalates-overview

www.safecosmetics.org/about/reports.cfm  Science on phthalates

www.thinkbeforeyoupink.org/Pages/Resources.html Difficulty of avoiding phthalates

www.cdc.gov/exposurereport/pdf/factsheet_phthalates.pdf

References

Kim IY, Han SY, Moon A. Phthalates inhibit tamoxifen-induced apoptosis in MCF-7 human breast cancer cells. J Toxicol Environ Health A. 2004;67(23-24):2025-35.

Main KM, Mortensen GK, Kaleva MM, Boisen KA, et al. Human breast milk contamination with phthalates and alterations of endogenous reproductive hormones in infants three months of age. Environ Health Perspect. 2006;114(2):270-276.

Okubo T, Suzuki T, Yokoyama Y, Kano K, Kano I. Estimation of estrogenic and anti-estrogenic activities of some phthalate diesters and monoesters by MCF-7 cell proliferation assay in vitro. Biol Pharm Bull. 2003;26(8):1219-24.

Swan SH, Main KM, Liu F, Stewart SL, et al. Decrease in anogenital distance among male infants with prenatal phthalate exposure. Environ Health Perspect. 2005;113(8):1056-1061.