Phthalates are industrial plasticizers widely used in personal care products to moisturize and soften skin, to dissolve and coalsesce ingredients, and to impart flexibility to nail polish after it dries. More than two decades ago, scientists began building a body of work indicating that phthalates are reproductive and developmental toxicants in laboratory animals, particularly in males. Early studies focused on phthalates’ ability to cause testicular atrophy (e.g., Gray and Buttersworth 1980). New studies are confirming these findings in humans (Swan et al. 2005, Main et al. 2005).
In August 2005 researchers from the University of Rochester published data showing delayed sexual development in baby boys exposed in utero to phthalates commonly found in personal care products, including the fragrance ingredient diethyl phthalate (DEP) and the common nail polish plasticizer dibutyl phthalate (DBP) (Swan et al. 2005). The authors found that the median concentrations associated with these effects, which include a shortened anogenital distance and incomplete testicular development, are below those the phthalate exposures found in one-quarter of the female population of the United States. They conclude that “[t]hese data support the hypothesis that prenatal phthalate exposure at environmental levels can adversely affect male reproductive development in humans.”
A second study published a month later (September 2005) found decreased testosterone levels among baby boys exposed to phthalates in their mother’s breast milk (Main et al. 2005).
These human data are remarkably consistent with results from laboratory studies. Phthalates are now known to cause a broad range of birth defects and lifelong reproductive impairments in laboratory animals exposed in-utero and shortly after birth targeting every organ in the male reproductive system (e.g., Ema et al 1998, Marsman 1995, Mylchreest et al 1998, 1999, and 2000, Gray et al 1999, Wine et al 1997).
In September 2000 scientists from the Centers for Disease Control and Prevention (CDC) reported finding phthalates in every one of 289 people tested, at surprisingly high levels. These tests, considered the first accurate measurements of human phthalate exposures, led the authors to conclude that “from a public health perspective, these data provide evidence that phthalate exposure is both higher and more common than previously suspected” (Blount et al. 2000). The tests showed higher levels of phthalates in women of reproductive age than any other group. CDC postulated that this difference could derive from personal care product exposures, which might vary by gender more than exposures from other common consumer products laden with phthalates (plastic, food wrap, and pharmaceuticals, for example).
Since the publication of CDC’s findings, the Environmental Working Group (EWG) has conducted two investigations on the prevalence and levels of phthalates in personal care products. The first, a study titled Beauty Secrets (EWG 2000), reported on the widespread use of dibutyl phthalate in nail polish, at levels up to five percent of product weight. The second, instigated by Healthcare Without Harm in partnership with Women’s Voices for the Earth and EWG, detailed results of a product testing program that found phthalates in nearly three-quarters of a wide range of products tested, despite the fact that none listed the phthalate ingredient on the label (Not Too Pretty, EWG et al. 2002). As these groups documented the common use of phthalates in personal care products, CDC published new results of phthalate testing in more than 2,500 people ages six and above, confirming their original findings: phthalate exposures are widespread across the population, and women are exposed at higher levels than men (with exposures expressed as “creatinine-adjusted,” corrected for urine concentration) (CDC 2003).
Cosmetic labelling requirements state that all cosmetics produced or distributed for retail sale to consumers for their personal care bear a list of ingredients, ordered by prevalence (21 CFR 701.3). Labeling requirements apply to all cosmetics marketed in the U.S., whether manufactured here or abroad. But ingredients used in fragrances or chemical mixtures that are considered trade secrets are exempt from labelling requirents. Industry sources have indicated that phthalates do not appear on the vast majority of products containing them simply because they are components of fragrance and thus exempt from labelling requirements. This gives consumers little power to avoid phthalates in their purchases of personal care products.
After the publication of product testing results in Not Too Pretty (EWG et al. 2002), the industry safety panel, the CIR, reviewed available toxicity data for DBP and other phthalates. These ingredients had last been reviewed by the panel in 1985, since which time scientists had conducted the bulk of the research demonstrating phthalates’ reproductive toxicity. At the same time that the E.U. was banning phthalates from use in personal care products (DBP and DEHP), the CIR again found phthalates “safe for use in cosmetic formulations in the present practices of use and concentration” (CIR 2003).
The panel made this finding based in part on an exposure estimate proposed by the cosmetic trade association, CTFA, that relied on phthalate testing results for 72 products conducted by public health and environmental groups (EWG et al. 2002). Although CTFA claims as its members 600 companies (CTFA 2004), the organization could find no more comprehensive source of data on phthalate levels in products than that provided by testing paid for by public interest groups, targeting 72 of the presumably thousands of products manufactured by their members. If the industry wishes to retain what FDA calls their “well-established self regulation” (FDA 1995), they might do well to implement an industry-sponsored data collection program instead of relying on others for such data.
The industry panel’s assessment fell far short of standard scientific practice. Among other shortcomings, the panel failed to consider the fact that consumers using phthalate-laden cosmetics have a background burden of phthalates in their bodies from other sources of exposure; failed to incorporate in its estimates the significant fraction of women exposed to phthalates at levels exceeding the government’s safe dose, according to CDC’s testing programs (Kohn et al. 2000); failed to collect data on measured concentrations of phthalates in air, particularly in nail salons and rooms with poor ventilation, where inhalation may be a significant source of phrthalate exposure; and failed to consider the ability of penetration enhancers, used in more than half of all personal care products, to increase the absorption of phthalates through the skin.
Although the industry’s trade group and safety panel have not recommended that phthalates be phased out of cosmetics, many companies have taken the step on their own. Acknowledging requests made by a coalition of public health and environmental groups concerned about reproductive toxins in cosmetics, more than 200 companies have now indicated their plans to produce products free of two widely-used phthalates (dibutyl phthalate, or DBP, and diethylhexyl phthalate, or DEHP). This decision is consistent with E.U.-wide reformulation requirements banning their use in cosmetics that took effect September 2004.
Health impacts of phthalates. Scientists have shown that phthalates can damage the female reproductive system, but it is the male reproductive system that appears to be more sensitive. Phthalate exposures damage the testes, prostate gland, epididymis, penis, and seminal vesicles in laboratory animals (see, for example, Mylchreest et al. 1998). Most of these effects persist throughout the animal’s life, and include, specifically:
- Testicular atrophy — a defect that leads to reduced capacity to form sperm and male sex hormones;
- Hypospadias — a defect of the penis in which the opening occurs on the bottom of the penis instead of the tip;
- Undescended testicles — a condition in which the testes fail to descend into the scrotal sac during pregnancy;
- Ectopic testes — a condition in which testes are grown outside the scrotal sac;
- Absent testes — testes are not formed at all;
- Absent prostate gland — the prostate gland contributes liquid secretions to semen;
- Absent or small seminal vesicles — these structures, like the prostate gland, contribute liquid secretions to semen;
- Reduced sperm count — leads to reduced fertility;
- Malformed or absent epididymis — the epididymis is the structure where sperm mature and are stored.
Trends in human male reproductive health include many of the same effects seen in lab animals dosed with phthalates. Although a cause and effect relationship has not been established, the ubiquity of phthalates in the human population validates the notion that phthalates may be contributing to these problems. Until proven safe, phthalates should be considered as potential contributors to the following human health effects:
- Declining sperm count — An analysis of 101 studies (1934-1996) by Dr. Shanna Swan of the University of Missouri confirms results of previous studies: average sperm counts in industrialized countries are declining at a rate of about one percent each year (Swan et al 2000).
- Hypospadias — Data from the Centers for Disease Control show that rates of hypospadias in the U.S. began climbing in about 1970, and continued this increase through the 1980s. This condition is a physical deformity of the penis in which the opening of the urethra occurs on the bottom of the penis instead of the tip. Currently the occurrence of hypospadias appears to be stable, at about 30 to 40 cases per 10,000 births (Paulozzi 1999).
- Undescended testicles — This birth defect, where testicles fail to completely descend into the scrotum during pregnancy, occurs in two to five percent of full-term boys in Western countries. Rates of the defect increased in the U.S. in the 1970s and 1980s. Men born with this defect are at higher risk for testicular cancer and breast cancer (Paulozzi 1999).
- Testicular cancer — This is the most common cancer of young men in many countries, including the U.S. Its incidence continues to increase at a rate of about two to four percent each year in industrialized countries, although rates
appear to have stabilized in the U.S. after a 20-year increase. Men with hypospadias, infertility, and undescended testicles — the same constellation of conditions seen in lab animals exposed to certain phthalates — are at greater risk for developing testicular cancer (Toppari et al 1996 and Moline et al. 2000).
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