Phthalate and Organophosphate Plasticizers in Nail Polish: Evaluation of Ingredients and Labels

Abstract

In the last decade, nail polish manufacturers largely phased out use of the three widely publicized “toxic trio” chemicals, including the plasticizer dibutyl phthalate (DnBP). These “3-Free” nail polishes may instead contain the plasticizer triphenyl phosphate (TPHP), a possible endocrine disruptor. Nail polish users and majority-Vietnamese nail salon workers in the U.S. are vulnerable populations potentially exposed to these plasticizers. To better understand plasticizer ingredient substitution, this study aimed to 1) identify plasticizer-related nail polish product labels through online searches, and 2) measure levels of 12 phthalate and 10 organophosphate plasticizers in 40 nail polishes. The 40 samples comprised different colors from 12 brands selected based on popularity and label variety. Summary statistics and Wilcoxon rank sum tests were calculated for plasticizer levels, substituting half the detection limit for non-detect values. We identified 11 n-Free labels ranging from 3-Free to 13-Free that reported the exclusion of n ingredients, with 5-Free the most common. The label definitions varied by brand, with 6 different definitions of 10-Free. Over half of nail polishes 6-Free or higher advertised the exclusion of TPHP. For the 40 samples, concentrations reached up to 7940 µg/g for organophosphates (TPHP) and 331 µg/g for phthalates (bis[2-ethylhexyl] phthalate [DEHP]). All DnBP levels were below 0.5 µg/g. TPHP levels were statistically lower in the 28 newer generation 5- to 13-Free samples compared to the 12 conventional or 3-Free samples (median 0.001 vs. 3730 µg/g, p<0.001). DEHP levels were statistically higher for the 16 nail polishes without detection of TPHP than the 24 with detection (68.5 vs. 1.51 µg/g, p<0.05). In conclusion, the evolving nail polish labels are varied and diversely defined. Our results suggest that DnBP and TPHP are now excluded or reduced from many polishes, but some concerns about plasticizer ingredients remain.