TUESDAY, APRIL 9, 2019
By Tasha Stoiber, PhD, Senior Scientist
Parabens are a group of chemicals widely used as artificial preservatives in cosmetic and body care products since the 1920s. Since cosmetics contain ingredients that can biodegrade, these chemicals are added to prevent and reduce the growth of harmful bacteria and mold, increasing the shelf life of the product. The concern with these chemicals is that scientific studies suggest that parabens can disrupt hormones in the body and harm fertility and reproductive organs, affect birth outcomes, and increase the risk of cancer. They can also cause skin irritation. Moreover, studies have detected parabens in nearly all urine samples taken from adults in the U.S., regardless of demographic (Ye 2006).
Given the endocrine disruption capacity and documented female and male reproductive harm, coupled with the potential for repeated lifelong exposure, it is clear that long-chain parabens (isobutyl-, butyl-, isopropyl- and propylparaben) should not be used in personal care or cosmetic products. Further, products can be made without these chemicals.
What Products Contain Parabens
Parabens are used in a wide variety of leave-on and rinse-off products, especially those with a high water content, such as shampoos and conditioners, which people use every day. Their antimicrobial properties are most effective against fungi and gram positive bacteria. Moisturizers, face and skin cleaners, sunscreens, deodorants, shaving gels, toothpastes, makeup and many other products contain parabens. They are absorbed into the body through the skin, metabolized and excreted in urine and bile (Soni 2005). However, daily use of a product or multiple products containing parabens results in direct and continuous exposure, as indicated by nearly ubiquitous detection in biomonitoring surveys.
Personal care products are the greatest contributors to paraben exposure, as seen in studies comparing paraben levels in the bodies of women, men, adolescents and children who regularly use cosmetics and those who do not. Adolescent girls who wear makeup every day had 20 times the levels of propylparaben in their urine compared to those who never or rarely wear makeup (Berger 2018). The use of body and face lotions, hair products, sunscreens and makeup have all been predictors of and correlated with remarkably increased levels of urinary parabens (Sahki 2018, Nassan 2017, Braun 2014 and Fisher 2017).
Products containing these four parabens from EWG’s Skin Deep® database:
Skin Deep Score*
Number of Products
* Scores of 7 to 10 indicate a high hazard. (https://www.ewg.org/skindeep/)
People can also be exposed to parabens by eating foods and beverages that do not just contain parabens but are also preserved with them. In the 1970s, propylparaben was designated as “generally recognized as safe” for addition to food up to 0.1 percent (CDC 2016). But this safety label is outdated, given the recent studies that point to health effects associated with parabens.
Types of Parabens
Cosmetics typically contain mixtures of different types of parabens. The most commonly used six types are methyl-, ethyl-, propyl-, isopropyl-, butyl- and isobutylparaben. The so-called shorter-chain parabens, methyl- and ethyl-, are commonly used in combination, whereas butylparaben is often used alone. The longer-chain parabens, propyl- and butyl-, are linked to stronger estrogenic activity (Blair 2000 and Vo 2010). The branched structure has been shown to increase estrogenic activity as well as sensitization potency (Darbre 2002 and Sonnenburg 2015).
Endocrine disruption and reproductive harm
Parabens can act like the hormone estrogen in the body and disrupt the normal function of hormone systems affecting male and female reproductive system functioning, reproductive development, fertility and birth outcomes. Parabens can also interfere with the production of hormones. The U.N. Environment Programme has identified parabens as a group, including propyl- and butylparaben, as endocrine-disrupting chemicals or potential endocrine-disrupting chemicals (U.N. Environment 2017). The Danish Centre on Endocrine Disruptors has also identified butyl- and isobutylparaben as endocrine disruptors (Danish Centre on Endocrine Disrupters 2018).
Scientific studies have reported the estrogenic activity of parabens (Byford 2002, Kim 2011, Vo 2011, Vo 2010). The estrogenic potency increases with the length of the paraben (Blair 2000 and Vo 2010) and branching side chains also increase estrogenic activity, as observed in in vitro and in vivo studies (Darbre 2002).
In animal studies, propyl-, isopropyl- and isobutylparabens disrupted hormone signals, and exposure to all these parabens and butylparaben harmed female reproductive development (Vo 2010). In another animal study, developmental exposure to butylparaben harmed male reproduction by decreasing sperm production and lowering testosterone levels (Zhang 2014). Boberg (2016) found exposure to butylparaben during development in rats harmed both female and male reproductive systems. Sperm count was decreased at very low doses of only 10 mg/kg of body weight per day.
In human studies, researchers from the Harvard T.H. Chan School of Public Health found decreased fertility was associated with urinary propylparaben (Smith 2013). Another human study linked butylparaben and total urinary paraben levels with decreased fertility, as indicated by decreased menstrual cycle length (Nishihama 2016). Butylparaben levels in the mother’s urine and levels in cord blood were associated with increased odds of pre-term birth and decreased birth weight (Geer 2017).
Endocrine disruption and cancer
Scientists are concerned about the exposure to environmental estrogens and how they may contribute to the risk of cancer, particularly breast cancer in women. Propylparaben can alter the expression of genes, including those in breast cancer cells (Wróbel 2014), and accelerate the growth of breast cancer cells (Okubo 2001). A recent University of California-Berkeley study found that low doses of butylparaben, previously not considered harmful, worked in conjunction with other cell receptors to switch on cancer genes and increased the growth of breast cancer cells (Pan 2016).
The skin can become sensitized to products containing parabens, which results in irritation (CIR 2006). The potency of sensitization has been shown to be related to the side-chain length of parabens (Sonnenburg 2015).
Parabens in the Body
In National Health and Nutrition Examinations Surveys, the Centers for Disease Control and Prevention, or CDC, detected propylparaben in greater than 92 percent of Americans tested, and butylparaben in about 50 percent of those tested (Calafat 2010). These results were similar to levels measured in adolescent girls in the 2016 HERMOSA intervention study (Harley 2016). Following just a three-day intervention, when the girls used products without parabens, propylparaben levels in urine dropped by about 45 percent.
Parabens have been detected in infants (Calafat 2009) and older children (Calafat 2010), as well as adults, including pregnant women (Smith 2013). Therefore, exposure may begin in early life stages and be continuous.
Parabens may also bioaccumulate in the body over time in fat tissue, as metabolites of parabens measured in fat were correlated with age (Aracho-Cordón 2018 and Wang 2015).
Parabens are also linked to ecological harm, as low levels of butylparaben can kill coral, according to laboratory tests (Danaovaro 2008). Parabens have been detected in surface waters, fish and sediments (Haman 2015). When parabens are combined with chlorinated tap water, a number of chlorinated paraben byproducts can form (Canosa 2006). Little is known about the toxicity of these byproducts, which may be more persistent (Haman 2015).
Actions To Protect Against Parabens
Major retailers in the U.S. have planned or already have in place active bans or restrictions (EDF 2019). Whole Foods Market bans all four parabens as part of its premium body care standard. CVS has committed to removing them in CVS store brand products by 2019 and in all beauty, personal care and baby products at Target by 2020. Rite Aid lists butyl- and propylparaben on its restricted substances list to phase out of some products by 2020. Walgreens has committed to removing isopropyl- and isobutylparaben by 2021.
Since 2015, the EU has banned isopropyl- and isobutylparaben in all personal care products, because of the European Commission’s Scientific Committee on Consumer Safety declaration that “adequate evidence has not been provided for the safe use of propyl- or butylparaben in cosmetics” (SCCS 2013). These parabens are also banned in personal care products in 10 Southeast Asian countries, as determined by the intergovernmental Association of Southeast Asian Nations (ASEAN).
The use of propyl- and butylparaben is restricted in the EU, ASEAN and Japan.
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