Nail Polishes Contain Undeclared DEHP, Among Other ‘Regrettable Substitutions’ – Study

A study led by Harvard public health researchers explores a multipart question: If dibutyl phthalate has been phased out of nail polishes, what plasticizers are replacing the ingredient, are they labeled or otherwise declared, and are they any safer than DBP?

The media is in a tizzy over a new study on nail polish chemicals and claims, and NGOs are likely to trumpet its findings as well, though the analysis does nothing to alter the risk picture for ingredients that industry maintains are safe. 

Published Oct. 10 in the American Chemical Society’s Environmental Science & Technology, the study – “Phthalate and Organophosphate Plasticizers in Nail Polish: Evaluation of Labels and Ingredients” – was led by Anna Young and other researchers at the Harvard T.H. Chan School of Public Health.

According to the authors, manufacturers of commonly used nail polish brands, particularly those sporting “3-free” claims and higher-integer variations – e.g., “10-free” – seem to have discontinued use of dibutyl phthalate (DBP), based on the limited sample set they analyzed.

Further, levels of triphenyl phosphate (TPHP) in 3-free, n-free (beyond 3-free) and other popular nail polishes appears to be on the decline.

The researchers assert those discoveries as signs of clear progress since 2012 when California’s Department of Toxic Substances Control found evidence of DBP (as well as toluene) in nail products marketed as 3-free, and detected presumed substitute TPHP – at that time “an emerging chemical of potential concern” in California – in much higher concentrations than those identified by Young, et al. (Also see "Mislabeled Nail Polishes Warrant Increased Regulation – California DTSC" - HBW Insight, 16 Apr, 2012.)

“The finding that our samples do not contain added [DBP] and that TPHP use had decreased demonstrates a public health success in which scientific research about harmful ingredients has successfully reached industry and impacted manufacturing practices,” the authors say.

Of course, not everyone agrees that TPHP and DBP, aka DnBP, are harmful. According to the Personal Care Products Council’s CosmeticsInfo.org, authoritative sources have concluded that neither DBP nor TPHP poses risks to human health under typical cosmetics use practices.

But Young et al. point to a handful of studies published since 2010 that they say have linked TPHP to adverse hormonal effects similar to those commonly associated with DBP, which they characterize as a reproductive and developmental toxicant.

The former’s increasing use as a stand-in for DBP is an example of a regrettable substitution “in which toxic chemicals are replaced with compounds (sometimes of the same chemical class) that are later found to also be toxic,” the researchers say.

“We should remain cautious about the understudied toxicity of plasticizers being introduced into nail polish. Overall, our results indicate a possibly recurring pattern of substituting plasticizers without evaluating the replacement for toxicity,” the investigators assert.

The majority of the nail polishes that Young et al. found to contain TPHP at levels above 10 micrograms/gram listed the ingredient on labeling, or brands otherwise communicated its use, though one of the highest detected TPHP concentrations (>1,000 μg/g) was for a product labeled as free of the substance.

Young et al. also detected undisclosed di(2-ethylhexyl) phthalate (DEHP) at levels of 100 μg/g to 1,000 μg/g. Based on information in patents reviewed by the group, 100 μg/g is the threshold at which plasticizers have a functional effect on nail polish, which then mandates their declaration on labeling.

Specifically, DEHP was present in eight of the 40 products the investigators tested (three of 12 brands), including in three nail polishes (from a single brand) positioned as DEHP-free.

Nail polish samples without measurable levels of TPHP tended to have significantly higher concentrations of DEHP compared to samples with measurable TPHP.

The authors infer that DEHP is another ingredient increasingly serving as a plasticizer in nail polishes in the absence of DBP. This is concerning, they say, because DEHP is an endocrine-disrupting chemical known to cause adverse reproductive health effects, impaired development and metabolic disruption.

Further, it’s a possible human carcinogen, according to Young et al., who note that DEHP is banned from cosmetics use in the European Union along with DBP.

DEHP was not identified in California DTSC’s 2012 survey, and according to PCPC, it isn’t used in cosmetic products. Perhaps that’s no longer true, if the Harvard study is a reliable indication.

PCPC notes that the chemical’s prohibition in Europe is based on its classification as a suspected reproductive toxin, which makes it automatically banned in the cosmetics sector regardless of use concentration or other factors that can mitigate risk. (Also see "EU Watch: Next Steps Re Controversial CMR Ban Approach, Fragrance Allergens Labeling " - HBW Insight, 10 Jul, 2018.)

Lack Of DEHP Disclosure, Unstudied Replacements Are Concerns

Overall, Young et al. analyzed the 40 selected nail polishes for 12 phthalates and 10 organophosphate plasticizers and detected 13 of the 22 ingredients, mostly at levels below 10 μg/g.

P,p′-1,3-phenylene p,p,p′,p′-tetraphenyl ester phosphate (PBDPP), 2-ethylhexyl diphenyl phosphate (EHDPP) and di-n-octyl phthalate [DnOP], also were found in amounts exceeding 10 μg/g, but generally not in concentrations that would be functional and necessitate listing on product labels.

The researchers identified TPHP and DEHP in 60% and 98% of samples, respectively, and those substances accounted for most of the highest measured, functional concentrations.

TPHP was the only measured plasticizer that manufacturers disclosed on labels, in Safety Data Sheets or via other informational materials, according to the study. Not one brand/product they looked at declared DEHP use.

Failures in DEHP disclosure – including in cases where the ingredient was specifically claimed to be excluded – represent possible risks to users’ and workers’ health, they suggest.

Other plasticizers ostensibly being used to prop up nail polish performance in lieu of DBP are inadequately studied for safety, Young et al. say. They cite acetyl tributyl citrate and trimethyl pentanediyl dibenzoate as examples of apparent DBP replacements that were listed on product labeling but which the researchers did not test for.

ATBC “has been found in some animal studies to potentially impact the endocrine system,” the study authors say. “We should remain cautious about the understudied toxicity of plasticizers being introduced into nail polish. Overall, our results indicate a possibly recurring pattern of substituting plasticizers without evaluating the replacement for toxicity.”

Rather than removing problematic plasticizers one at a time – and then adding them to the tally denoted by n-free claims – “our results reinforce the need for the nail polish industry to remove harmful classes of chemical, test any ingredient substitutes for safety before use, and design safer ingredient alternatives following known validated frameworks,” the authors assert.

At the same time they recognize that the wholesale elimination of plasticizer additives could compromise the performance characteristics that nail polish consumers have come to expect.

Use of n-free claims also is in need of reform, according to Young et al., who found such statements to be ill-defined in many cases and to lack standardization overall as to the chemicals covered by 3-, 5- and 10-free claims (among other numerical variations).

The nail polish market – and consumer confidence – would benefit from mechanisms for third-party validation of such claims, they say.

Other market watchers have highlighted continued use of the so-called “toxic trio” in nail products, as well as unsupported claims in the category regarding toxic ingredient omissions, as potential liabilities for companies in a litigious US climate. (Also see "Global Corporate Insurer Projects Increased Liability For ‘Toxic Trio’ Use In Cosmetics" - HBW Insight, 27 Sep, 2018.)

The study is making waves in the mainstream media, with predictably ominous headlines – for example, “Even 'Non-Toxic' Nail Polish May Contain Harmful Chemicals” (Time) and “Your ‘Nontoxic’ Nail Polish Is Probably Still Full Of Poison” (New York Post).

Industry’s biggest problem could be California’s response.  (Also see "Nail Polish Study Making Waves; Will California’s DTSC Be Swept Up?" - HBW Insight, 12 Oct, 2018.)