Hidden Hazards

Health Impacts of Toxins in Polymer Clays

Polymer clays are a form of modeling clay that have become popular in recent years among children, adolescents and adult craftspeople. Unfortunately, these clays contain polyvinyl chloride (PVC) mixed with phthalate plasticizers. While the phthalate plasticizers make the clay soft and workable, they are also associated with potential health risks. Phthalates as a class of chemicals have been implicated in birth defects, reproductive problems, nerve system damage and other negative health effects.



Polymer clays are a form of modeling clay that have become popular in recent years among children, adolescents and adult craftspeople. They are inexpensive, come in a variety of colors, are soft at room temperature, can be molded by hand into small or large items, and can be baked in a conventional oven at low heat, resulting in a permanent hard object. Fimo and Sculpey are the most common brand names of polymer clays in the U.S., but other different product lines exist.

Unfortunately, these clays contain polyvinyl chloride (PVC) mixed with phthalate (pronounced tha-late) plasticizers. While the phthalate plasticizers make the clay soft and workable, they are also associated with potential health risks. Phthalates as a class of chemicals have been implicated in birth defects, reproductive problems, nerve system damage and other negative health effects.

VPIRG’s research indicates that children and adults using polymer clays may be exposed to phthalates at harmful levels. Even when clays are prepared following proper package directions, children and adults can breathe or ingest high levels of phthalates. In addition to phthalate exposure the research indicates that when polymer clay is overheated enough or accidentally burned, the PVC will break down and release highly toxic hydrochloric acid gas.

The potential for exposure to phthalates from normal use of polymer clays is troubling given the popularity of the clays both at home and at schools, the inadequacy of consumer warnings about the effects of these chemicals, and the effects phthalates may have on children. Moreover, since the Federal Toxic Substances Control Act does not require pre-market testing for new industrial chemicals, and because it is difficult to restrict the use of existing chemicals in commercial products, exposure to phthalates is cause for concern.

VPIRG recommends that consumers avoid using polymer clays and calls on the Consumer Products Safety Commission (CPSC) to recall or suspend sale of polymer clays until they are shown to be safe for use by children and pregnant women. If the products remain on the market – VPIRG calls on manufacturers to provide adequate warnings to consumers as to why they should avoid use of the products or take special precautions when using them. Finally, state Attorneys General should investigate the claims by manufacturers that the clays are “non-toxic.”

Health Risks of Phthalates
Phthalates are associated with a diversity of negative health impacts including reproductive defects, birth deformities, liver and thyroid damage, neurological impacts as well as miscarriages. At least one phthalate is listed as an EPA probable human carcinogen. The following list illustrates the health risks of some different phthalates:

• DnOP (Di n Octyl Phthalate) – Birth deformities, reproductive disorders, liver and thyroid impacts, and linked to gene mutation in mixture with other compounds.
• DnHP (Di n Hexyl Phthalate) – Reproductive disorders, liver and thyroid impacts, linked to gene mutation in mixture with other compounds.
•BBP (Butyl Benzyl Phthalate) – Reproductive Disorders, birth deformities, suspected carcinogen, but studies inconclusive, and links to nerve disorders and miscarriages.
• DEHP ((2 ethylhexyl) Phthalate) – birth deformities, reproductive disorders, EPA “probable human carcinogen,” Dept. of
Health and Human Services “Potential Human Carcinogen,” liver, kidney and thyroid impacts.
• DINP (Di isononyl phthalate) – Reproductive disorders and developmental harm.
• DEHT (Di (2 ethylhexyl) terphthalate) – Unknown

Inadequate Research and Information about Phthalates
To date, only a few phthalate compounds are assumed to present the most significant exposure risk to humans. DEHP used in medical devices, and DINP used in children’s toys, have been the subject of much focus because they have been used in higher volumes than other phthalate esters. But regulators have significantly underestimated the general public’s exposure to other phthalates and combinations of phthalates in consumer products, and therefore have not comprehensively studied them. This is especially true for the phthalates found in polymer clays.

For example, the National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) panel assigned to study the risks phthalate exposures posed to human reproductive health suggested that BBP was of only “minimal” concern for reproductive effects in humans because exposures in adults were assumed to be low – around 2 micrograms per kilogram of body weight. Yet VPIRG’s research shows that a 20 kg (44 lb.) child using 100 grams of polymer clay could be exposed to as much as 130 times the 2 micrograms per kilogram of body weight of BBP the panel identified as normal daily exposure after only 5 minutes of play.

Moreover, recent evidence indicates that phthalate exposures are ubiquitous among the general population in the U.S. and, in some cases, higher than previously thought. Recently, CDC analytical chemists, analyzed thousands of urine samples from all over the U.S. and found multiple phthalate metabolites in all samples tested. These metabolites included less common phthalate esters. The CDC team theorized that the residues of these phthalate compounds may result from their presence in consumer products.

VPIRG’s Findings
VPIRG sent samples of Sculpey and Fimo polymer clay products purchased from local stores in Montpelier, Vermont to laboratories for both compositional analysis and exposure analysis.

Compositional Analysis
Laboratory testing of the clays by Philips Services (PSC) in Ontario Canada revealed that mixed phthalates made up between 11 and 14% of the total contents of each of the Fimo samples. The Sculpey samples each contained between 3.5 and 4.4 percent mixed phthalates.

The Fimo clays appeared to contain mostly DnOP, DnHP, DEHT and an unknown phthalate ester (named Unknown #2 by the lab) that strongly resembled DEHP. The Sculpey clays appeared to contain mostly BBP, and a mixture of DnOP and DEHT. Both brands of clays also contained significant amounts of several other phthalate compounds the lab was unable to positively identify using the customary phthalate standard.

Exposure Analysis
VPIRG commissioned the Environmental Quality Institute (EQI) at the University of North Carolina-Asheville to assess human exposure to phthalates when polymer clays are used according to packaging directions. Researchers at the lab, specializing in real-world environmental exposure assessment prepared and baked clay samples following the manufacturers’ directions, and measured releases of phthalates in the air and residues of phthalates on users’ hands.

The EQI lab found that, when prepared as directed, polymer clays could expose children and adults to significant concentrations of phthalates, including BBP, DnOP, and DnHP, from both handling the clays and breathing in air contaminated with phthalates during the baking process.

Inhalation Exposure
Regulatory agencies have not set allowable inhalation levels for the phthalates found in the polymer clays tested (BBP, DnOP, DnHP, DEHT). The Occupational Safety and Health Administration (OSHA) has however, established an eight-hour standard for adult workers’ exposure to DEHP and DEP, at 5 milligrams per cubic meter of air. Using this standard as a measure for comparison, inhalation testing showed that Fimo Lavender could result in phthalate exposures (to both BBP, DnOP/DEHT mix, and to unknown #2) twice this high at 11 milligrams per cubic meter. The average phthalate exposure from the clays other than lavender measured 2 milligrams per cubic meter – an amount that closely approaches the 5 milligram per cubic meter OSHA standard for adult workers when we consider that this standard is an adult standard only, and children are the primary users of polymer clay.

It is troubling that the average exposure to phthalates so closely approaches the OSHA standard because those exposed to phthalates are likely to be children. Children’s bodies are much smaller and more vulnerable to outside factors than adults’ bodies; they breathe more air per body weight than adults and are therefore exposed to more air contamination. The OSHA standard was created for adult workers, and the 5 milligrams per cubic meter OSHA standard is not likely to be adequate to use as a measure for phthalates exposure in children. For comparison, Federal pesticide law mandates setting an exposure limit for children ten times lower than the limit for adults if comprehensive testing data are not available (as is the case with phthalates).

Ingestion Exposure
Phthalate residues left on a user’s hands and ingestion levels were estimated using the Consumer Product Safety Commission’s assumption that 50 percent of material deposited on hands will be ingested by a child. Since regulatory agencies have not set standards for phthalate ingestion, state drinking water standards were used to compare the exposure levels found in the study. The results showed that a child who played for 5 minutes with 100 grams of five of the clays tested could exceed the maximum daily exposure level for the phthalate, BBP, allowed under Florida’s drinking water limit. Every single clay tested resulted in exposures exceeding Minnesota’s drinking water standard for BBP.

Cumulative Exposure
EQI’s analysis likely underestimates the potential phthalate exposures for many children using polymer clays. The researchers measured exposures for only four of the eight separate phthalate compounds identified in the clays. Further, while EQI researchers estimated exposures based on the use of 100 grams of clay, actual preparation of these clays may involve far larger quantities. Various polymer clay “recipes” include concoctions that demand about a pound (~450g) or more of polymer clay material. A child following a recipe for a one-pound project could be exposed to nearly five times as much phthalates as projected by the EQI analysis.

Moreover, this study has focused on the implications of exposure to only a few phthalate compounds. Simultaneous exposures to multiple related phthalate esters can easily take place through the routine preparation of polymer clays. This repeated exposure could have a cumulative impact that is not yet fully understood.

Unsatisfactory Consumer Warnings
Rather than warning consumers about phthalates in polymer clay products, packaging on polymer clays actually advertises the products as “environmentally friendly” and “non-toxic.” These misleading labels are based on the assumption by the Arts and Creative Materials Institute (ACMI), the organization approving the non-toxic label, that polymer clays only contain a few phthalate esters. However, VPIRG’s research shows that polymer clays contain phthalates other than those the ACMI considered. Non-toxic certification was granted to polymer clays even though not all the chemicals found in polymer clays were studied for health impacts. It should be noted that the ACMI is a consortium of art and craft material manufacturers.

Inadequate Federal Regulations
Because the U.S. regulatory framework does not require pre-market testing for new industrial chemicals before they are used in the marketplace, and it is difficult to restrict use of existing chemicals, many harmful chemicals end up in consumer products. Of more than 80,000 chemicals used in the marketplace today, the vast majority are untested for human health impacts. This is alarming because consumers may be exposed to chemicals like phthalates on a frequent basis without knowing what the health impacts from exposure may be.

In response to the results of these tests, VPIRG makes the following recommendations:

• The CPSC should declare a moratorium on the sale of polymer clay products until further investigation determines the risks for exposing users to phthalates, especially children and pregnant women. Decision makers should also re-evaluate regulations allowing manufacturers to incorporate harmful chemicals like phthalates into products intended for children without comprehensive health and safety testing.

• If polymer clay products remain on the market, manufacturers should be required to affix clear warning labels on polymer clay products, directing pregnant women and children to not use polymer clay products. Others should be warned to strictly limit contact with the clays by wearing gloves when manipulating the product and to also limit inhalation of clay chemicals by staying out of and ventilating the kitchen during and after baking.

• Decision makers should reform the laws that govern use of chemicals in industry and in products. These laws currently do not require comprehensive testing of industrial chemicals nor do they allow chemicals to be phased out or regulated even when there is evidence of health hazards. The Toxic Substances Control Act has not been updated since the 1970’s.

• Retailers should inform manufacturers of their concerns about selling potentially harmful children’s products that contain a “non-toxic” label, and should either take these products off their shelves or warn consumers of the potential for reproductive damage and birth deformities.

• Consumers should avoid purchasing polymer clay products until they are proven safe.

• State Attorneys General should investigate manufacturer’s claims that polymer clays are “non-toxic.”