Endocrine Disruptor In Nail Polishes Gets Into Women’s Bodies

October 19, 2015

Nailed: TPHP: a new endocrine disruptor

Scientists knew little about the toxicity of TPHP until recently. But now there is growing evidence that the chemical could affect hormones, metabolism, reproduction and development.

In a 2014 study, rats exposed before and after birth to the flame retardant mixture Firemaster 550®, which contains up to 20 percent TPHP, grew obese. The females went through early puberty, an indication of irregularities in hormone signaling (Patisaul 2013).   

In experiments with zebrafish, which scientists often use as a model to study endocrine disruption and development, researchers from Seoul National University in South Korea found that TPHP exposure altered sex hormone balance, which could harm reproductive performance.  The scientists observed that TPHP changed the gene expression of certain receptors that could increase or decrease hormone activity; this change could interfere with endocrine and developmental signaling (Isales 2015, Liu 2012, Liu 2013a, Liu 2013b). Research on zebrafish showed that TPHP interfered with reproduction and could cause heart defects (Du 2015, Liu 2013b, McGee 2013).

In experiments on animal cells, scientists from the Hokkaido Institute of Public Health in Japan found that TPHP stimulated receptors for female sex hormones and antagonized the receptors for male sex hormones (Komija 2013). These fluctuations in the hormone system could alter reproductive function.

In another set of experiments, scientists from Boston University, the University of Cincinnati College of Medicine, Duke University and North Carolina State University found that Firemaster 550® activated the body’s “master regulator” of the process that governs the development of fat cells (Belcher 2014, Pillai 2014). The Duke/Boston team reported that Firemaster 550® stimulated fat cell maturation. Further experiments showed that TPHP diverted immature cells away from bone formation and toward fat development. Together, these results suggest TPHP could contribute to obesity. 

TPHP has some structural similarity to tributyl tin—a substance suspected as a contributor to obesity because it can alter biological activity in a manner that leads to fat accumulation in animals exposed during early development.

A study led by a researcher at the University of Michigan School of Public Health found that adult men exposed to TPHP via house dust had lower sperm counts and produced more prolactin, a hormone that stimulates breast development and milk production in women (Meeker 2010). A second study led by the same team associated decreased semen quality with higher urinary concentrations of DPHP (Meeker 2013).

These and other recent studies raise serious questions about the possible impact of TPHP on hormones and fertility. Yet the chemical is hard to avoid. American manufacturers produced or imported more than 10 million pounds of TPHP in 2012 (EPA 2014). The biggest U.S. manufacturer of TPHP is a single chemical company, ICL-IP, which is a leader in the American fire retardant chemical market. The same company also makes plasticizers for a variety of industrial uses. EWG scientists could not determine how much TPHP from any source winds up in nail polish.