The U.S. phthalates industry, represented by the Phthalate Esters Panel of the American Chemistry Council (ACC), is dedicated to the continued safe use of phthalates, a family of compounds primarily used to soften vinyl. Phthalates provide many product and consumer benefits—public health, performance, durability and function—and are used in many important applications for these reasons, from recreational and safety equipment to building and construction materials. Phthalates are among the most thoroughly studied families of compounds in the world and have a long history of safe use.
Phthalates Basics
Phthalates Restrictions
Phthalates and Health
Phthalates Basics
Q. What are phthalates?
A. Phthalates are a family of compounds whose primary use is as a vinyl softener. They are colorless, oily liquids with little or no odor and low volatility. Phthalates provide many product and consumer benefits—public health, performance, durability and function—and are used in many important applications for these reasons, from recreational and safety equipment to medical devices to building and construction materials.
Q. What are phthalates used for?
A. Phthalates are the primary plasticizer in use today because of performance, cost, durability, and overall product sustainability benefits. Primarily, phthalates are an important ingredient in flexible vinyl products, such as wiring and cabling, wall covering and flooring. They are also used in vinyl blood bags and IV tubing used to help save lives. Other phthalates are used as solvents or fixatives, for example, to make fragrances last long.
Q. What is known about the safety of phthalates?
A. Phthalates are among the most thoroughly studied family of compounds in the world and have a long history of safe use. An immense amount of information on the safety profiles of various phthalates is available to the public and users of this Web site.
Q. Do phthalates leach out of products and accumulate in our bodies?
A. Phthalates do not migrate out of products easily and they do not build up in the body. Phthalates begin to break down within minutes and are eliminated from the body within hours. Based on U.S. Centers for Disease Control and Prevention (CDC) studies, average phthalates exposures are far below levels set by U.S. federal agencies to be protective of human health.
As an example, Dr. Michael Kamrin, Professor Emeritus at Michigan State University's Institute for Environmental Toxicology, concluded that human exposures to the phthalates of most concern are generally thousands of times lower than the lowest adverse effect levels for these phthalates, even in the most sensitive animal species.
Q. Shouldn’t the effects of phthalates be studied as a whole, because various phthalates can act in the same ways on organisms?
A. Even if you add up the effects of the different phthalates that might be expected to act in the same way on organisms, CDC data tells us that exposure is still below federal safety levels. Dr. Robert Benson, acting independently from his role in the U.S. Environmental Protection Agency, assessed the daily human dose of all the phthalates that show adverse effects in rats to see if the combined effects would exceed government safety levels. His conclusion, published in the March 2009 issue of Regulatory Toxicology and Pharmacology stated that “…it is unlikely that humans are suffering adverse effects from current environmental exposure to these phthalate esters.”
Phthalates Restrictions
Q. Why have phthalates been restricted from personal care products in Europe?
A. This restriction is not due to the finding of any human health effects. The European Cosmetics Directive states that any substance known or strongly suspected to have certain health effects in laboratory animals—even if this occurs only at extremely high doses—might present similar risks to humans, and may not be used in cosmetics. The directive is not based on any evidence that there is actual risk to humans. In fact, a European Union (EU) safety review stated that there is “no concern for consumers” who use nail polish containing the phthalate DBP. » learn more about phthalates and personal care products
Q. Why did the U.S. and EU restrict the use of phthalates in toys?
A. The decisions to restrict the use of phthalates in children’s products in not based on science. Importantly, after phthalates were restricted in the U.S. as part of the Consumer Product Safety Improvement Act (CPSIA), a scientist at the U.S. Consumer Product Safety Commission (CPSC) stated that she did not believe that phthalates “posed a risk of injury to children.”
Similarly, the European legislature voted to restrict phthalates, even though the draft conclusion of an exhaustive safety review of the principal phthalate used in toys stated it was “unlikely to pose a risk” even for newborns. » learn more about phthalates and children's toys
Phthalates and Health
Phthalates are among the most thoroughly studied families of compounds in the world. Because of this, it is not unusual for new studies to be reported every week. And, while some of these studies have suggested a link between phthalates and various human health effects, none has demonstrated an actual causal link (that phthalates are the cause of the effect). Because phthalates are found in many consumer products, most people are exposed to phthalates every day, but phthalates don’t migrate out of products easily and they don’t accumulate in our bodies. In fact, they begin to breakdown within minutes and are metabolized within 12 to 24 hours.
Below are answers to some common questions based on what you may have heard or read about phthalates and human health effects. Importantly, no single epidemiological study—the search for elements that might contribute to a health problem—can prove an actual cause-and-effect link. That’s why the authors of these studies never fail to caution against drawing conclusions, and advise on the essential need to replicate the results. It is important, therefore, to keep these cautions in mind when reading about these studies.
Q. Isn’t it true that phthalates cause health problems in laboratory animals?
A. Some—not all—phthalates interfere with the development of the reproductive systems of male rodents when administered in huge doses—doses far larger than CDC data reports of humans experiencing. Rodent effects are not necessarily relevant to humans. A number of studies indicate that humans do not absorb phthalates as readily as rodents do. Humans break phthalates down and excrete them much more readily than rodents do. This evidence suggests that rodent effects may not apply to humans. In fact, tests on male marmosets, which are primates, showed that even huge doses administered from weaning until sexual maturity had no effect on their reproductive organs.
Q. Is there any evidence that phthalates don’t affect humans?
A. In a 2009 research study conducted in the Edinburgh, Scotland, laboratory of endocrinologist Dr. Richard Sharpe, doses of a phthalate in concentrations high enough to cause adverse effects in the reproductive systems of male rodents were given to pregnant marmoset monkeys, which are primates and thus much more similar to humans than are rodents. Males born to the pregnant monkeys showed no gross testicular structural damage and no other effects on the reproductive system development, male hormone levels, or on their number of germ cells, and no hypospadias (malformations of the urethra in males) all the way through to adulthood.
Q. Haven’t phthalates been linked to human sexual development?
A. A few studies have attempted to link phthalates to human reproductive effects. But these studies often have severe limitations and flaws in the study designs, such as small sample sizes, uncontrolled variables or poor statistical methodology. Therefore, conclusions they draw regarding human health effects are often inconsistent from study to study or contradict the animal data. None of these studies established a causal link (actual cause and effect) between phthalates exposure and reproductive health effects. Furthermore, the National Institutes of Health, through its National Toxicology Program, reviewed multiple studies claiming to show human effects and, in late 2006, called them “insufficient” to warrant drawing any conclusions.
Q. Does that include the Swan study?
A. The Swan study, conducted by Dr. Shanna Swan in 2005, failed to establish that any claimed changes in reproductive development of infants were caused by exposure of their mothers to a combination of four phthalates. In addition, in a later published study using the same data but different mechanistic method, Dr. Swan reached contradictory conclusions and was still not able to form a causal link of prenatal phthalates exposure and adverse reproductive effects in humans. Dr. Rebecca Goldin, a mathematician at Statistical Assessment Services (STATS), questioned the credibility of this study: “How much data fiddling was required to find a result?” Others have criticized the study’s methodology, its clinical data, and even its biological plausibility.
Q. Aren’t phthalates endocrine disruptors?
A. It is misleading to characterize phthalates as endocrine disruptors, or endocrine mimics. The major phthalates in commerce today do not interfere with either the estrogen or androgen receptors when tested in laboratory animals. That is, they neither activate the male or female hormone receptors, nor prevent activation by natural hormones.
High doses of some phthalates can interfere with normal sexual development in male rats, but this is not true in mice or monkeys and, therefore, is unlikely in humans given that there are significant differences in the male reproductive tracts of rodents vs. primates. Studies show that reactions to phthalates exposure vary from species to species; mice are less sensitive than rats, and primates simply do not absorb phthalates as efficiently as rodents do. » learn more about endocrine disruptors
Q. Do phthalates cause cancer?
A. The International Agency for Research on Cancer (IARC), an arm of the World Health Organization, stated that one phthalate ester in particular—DEHP—is “not classifiable” as a human carcinogen. The basis for that decision is ample evidence that the biological process leading to cancer in rodents does not occur in humans. The IARC has also looked into BBP and found available studies “inadequate to evaluate the carcinogenicity of butyl benzyl phthalate to mice and rats.”
In 1982, the National Toxicology Program (NTP), which classifies substances according to their tendency to be cancer causing in animals, placed DEHP in its second category, as a compound “reasonably anticipated” to be carcinogenic to humans. (The top category is “known carcinogen.”) However, extensive research over the years has questioned this assumption. In an opinion presented by the EU Scientific Committee for Health and Environmental Risks in October 2008, the Committee stated that at the DEHP doses observed in humans, DEHP exposure did not represent a relevant cancer risk to humans.
Q. Haven’t phthalates been linked to asthma?
A. Some claims to that effect have been made, but laboratory studies have shown that phthalates do not trigger immune responses in rodents, and do not intensify existing asthma attacks. Tests for phthalates’ presence in house dust have been shown to be very low. » learn more about asthma
Q. Do phthalates cause allergic reactions?
A. Testing has not shown phthalates to be allergens, nor has testing shown them to be strong irritants, so allergy science tells us that it is unlikely that they could act as triggers for allergic reactions. » learn more about allergic reactions
Q. Is there any scientific evidence linking phthalates to autism?
A. There are no studies that have demonstrated that phthalates cause autism. One study by Swedish and U.S. researchers looked at the association between indoor environmental factors and autism and found the results “far from conclusive.” Importantly, the study did not track, measure or record any exposure to phthalates. The authors cautioned their conclusions were “puzzling, even baffling, and not readily explicable at this time” and that “further and more extensive exploration” is needed.
Q. Is there any scientific evidence linking phthalates to obesity?
A. No studies have found exposure to phthalates to cause obesity in humans. For example, one study by Teitelbaum et al., that looked into childhood obesity makes no claim that exposure to phthalates causes an increase in weight. The authors clearly report only a very preliminary statistical correlation between weight and phthalate exposure, and note further study is required. Moreover, we are not aware of any scientific evidence from decades of animal studies that links any phthalate to an increase in weight.
Q. Is there any scientific evidence linking phthalates to bone disease?
A. Decades of long-term animal studies show no connection between phthalate exposure and skeletal problems. A study of phthalate effect on animal osteoblasts by Sabbieti et al., exposed mouse and rat bone cells in culture dishes to full, intact phthalate molecules. However, what the researchers did to the bone cells is not what happens in living things—living organisms exposed to phthalates almost immediately break them up into smaller molecules that behave in a very different way. Thus, exposing cells in a dish to the whole molecule isn’t relevant to the way humans are actually exposed to phthalates in the real world.
Q. Do phthalates affect newborns’ birth weight?
A. Phthalates have not been shown to cause any birth weight abnormalities in infants. One study by Zhang et al., in China reported low birth weight in infants statistically correlated with phthalate exposure at birth. However, the authors of the Chinese study are cautious about their conclusions and noted the limitations of the study. Other studies, including one by Wolff et al., (2009) in Environmental Health Perspectives (EHP) and another published in Human and Ecological Risk Assessment, report no change in birth weight or other outcomes associated with phthalate exposure even though phthalate levels were unusually high.
Q. Do phthalates affect infants’ neurological development?
A. Previous animal tests involving very high doses of phthalates show no neurological effects in females or males. A 2009 study by Engel et al., claims that prenatal exposure to phthalates reduces newborn girls’ alertness. However, the study also found that the infant males showed no decline in alertness, and even a small increase in "motor performance,” indicating that phthalates have beneficial rather than detrimental effects on infants’ neurological development. The conflicting results suggest that the study is inconclusive, especially as the authors note that there is no known mechanism to explain the reported effect.
A recent report suggesting an association between phthalate exposure and attention deficit/ hyperactivity disorder (ADHD) is based on observations of symptoms, not on a clinical diagnosis of ADHD, and on a single measurement of phthalate metabolites in urine which provides no information on long term exposure levels.
