The Paraben Paradox: Safe Preservative or Fertility and Health Toxin?

Parabens are a group of chemicals that have been used since the 1920s as preservatives in many household products. These chemicals increase the shelf life of personal care products and some food items by limiting the growth of bacteria and mold. However, these anti-bacterial chemicals act as endocrine disruptors and are associated with several reproductive and health problems. Fortunately, less toxic options for preservatives are available, and choosing safer products may improve your fertility and overall health. Opinions on safety differ, so let’s review the evidence.

What Products Contain Parabens?

Parabens help increase the shelf life of many personal care products like makeup, shampoos, conditioners, moisturizers, toothpaste, sunscreens, deodorants, and more. In the 1970s, propylparaben was designated as safe to use as a preservative in food and beverages to decrease mold and bacteria growth in products. Parabens can also be found in supplements, vitamins, and some prescription medications. The Federal Food and Drug Administration (FDA) does not regulate the amount of parabens in foods or personal care products but does suggest the concentration of parabens in prescription drugs should not exceed 0.1% (Song 2017).

Types of Parabens

There are many types of parabens, usually designated by their size (short-chained vs. long-chained) and structure (simple vs. branched). The most common parabens in products are methyl-, ethyl-, propyl-, isopropyl-, butyl-, and isobutylparaben. The longer chained and more branched chemically structured parabens, propylparaben and butylparaben, are associated with stronger endocrine activity (Blair 2000, Darbe 2002, Sonnenburg 2015). 

How Common Are Parabens?

92% of Americans tested positive for propylparaben and 50% tested positive for butylparaben in a survey by the Centers for Disease Control (Calafat 2010). In this study, higher levels of parabens were found in women than men (possibly due to the assumption that many women use more personal care products compared to many men). Another trial, the HERMOSA intervention study, showed definitively that people who use more personal care products have higher levels of parabens in their bodies (Harley 2016). This trial showed higher levels of parabens in adolescent girls who use makeup regularly compared to adolescent girls who do not. Many parabens get metabolized quickly, and this trial showed a 45% drop in paraben levels in the urine of girls who stopped using paraben-filled cosmetic products for three days.

Parabens have been identified in adults, pregnant women (Smith 2013), older children (Calafat 2010), and infants (Calafat 2009). Studies have shown that some parabens can be stored in fat cells, and levels can accumulate over time (Aracho-Cordon 2018 and Wang 2015). One study estimates daily human exposure to parabens via personal care products was 5-50 micrograms/kg/day for adults and 15-230 micrograms/kg/day for infants and toddlers (Guo and Kannan 2013).

Parabens and Fertility

Parabens have been shown to attach to and alter endocrine receptors in the body, and the larger and more complex the structure of the paraben, the higher the impact to the receptor (Vo 2010 and Byford 2002). These chemicals have been shown to impact both female and male endocrine function. Laboratory studies show disruption in estrogen receptor and function (Blair 2000, Darbe 2002, Sonnenburg 2015) as well as androgen (male hormone) receptors, resulting in anti-androgenic effects and alterations in testosterone transcription (Kolatorova 2018). High levels of parabens have been associated with many female and male reproductive development and fertility issues. 

Reproductive system development: Animal studies have shown disrupted reproductive development in rats born to mothers with high exposure to parabens: female rodents can develop dysfunctional ovaries (Vo 2010) and male rodents can have lower testosterone and sperm production in adulthood (Oishi 2001). Parabens are one of many endocrine disruptors shown to impact reproductive track development. DES (diethylstilbestrol) is a synthetic estrogen compound that was used to prevent miscarriage and preterm delivery in the 1940s-1960s but was removed from the market in 1971 because daughters born to mothers who used DES in pregnancy had higher risk of uterine malformations and vaginal cancer (read more here).

Female infertility: There may be some correlation to increased paraben exposure and ovarian reserve. Smith et al. observed a lower antral follicle count and higher cycle day 3 FSH level with increasing urinary propylparaben (2013). Both low antral follicle count and high FSH levels have been associated with diminished ovarian reserve and lower success rates with fertility treatment (read more here). Nishihama et al. showed shorter average length of menstrual cycles in women with higher paraben levels (2016). Other studies show altered hormonal levels with high paraben exposure: increased levels of butylparaben have been associated with lower levels of endogenous estradiol levels, altered thyroid hormone levels, and shifts in estradiol/progesterone ratios in women (Aker 2016). One study following 501 couples in Michigan and Texas from 2005-2009 showed lower fertility rates in women with higher levels of methyl- and ethylparabens (Smarr 2016). In this study, the couples with the highest levels of urinary methylparaben took the longest time to conceive. 

Male factor infertility: Evidence varies on the impact of parabens on male reproductive health. Basic scientific research shows that parabens attach to and alter androgen (male hormone) receptors, resulting in anti-androgenic effects and alterations in testosterone transcription (Kolatorova 2018). Clinical studies vary, but some show an impact on testosterone production, sperm parameters, and fertility in men. In utero exposure to parabens in male rats has been associated with altered testicular development and poor sperm production in offspring (Guerra 2017). One study with over 300 men attending a fertility clinic showed poor sperm morphology, higher DNA fragmentation, lower sperm motility, and lower testosterone levels in men with high levels of five different parabens in their urine (Jureicz 2017). High levels of parabens have been associated with low sperm counts and decreased testosterone levels (Zhang 2014). Other studies show limited association between paraben levels in urine of men and their semen analysis parameters. One study of 190 men showed higher DNA damage in sperm with higher levels of butylparaben but no significant difference in other sperm parameters with methylparaben and propylparaben (Meeker 2011). There are limited studies on success with fertility treatment in relation to male levels of parabens, but one study with 218 infertile couples showed lower live birth rates in men with high levels of methylparaben doing intrauterine inseminations (IUI) for fertility treatment (Dodge 2015). 

Fertility treatment success and parabens: Studies examining fertility treatment outcomes with paraben exposure show mixed results. The EARTH trial of 245 women undergoing 356 in vitro fertilization treatment cycles showed no impact of levels of methyl-, propyl-, and butylparabens on total mature oocytes, proportion of high-quality embryos, fertilization rates, or treatment outcomes (Minguez-Alarcon 2016). One study on male patient paraben levels and IVF outcomes in 211 treatment cycles showed poor embryo quality but similar live birth rates in couples with male partners with high paraben levels (Dodge 2015). This same study reported on outcomes with IUI (intrauterine insemination) and did show lower live births in couples in which the male partner had high levels of urinary parabens. Further studies are needed to examine this discrepancy in outcomes based on type of fertility treatment.

 Parabens and Pregnancy

Parabens have been found in human cord blood, placental tissue, breast milk, and amniotic fluid (Kolatorova 2018). Some research suggests increased risk in pregnancy with paraben exposure. One study of parabens in pregnant mothers showed that higher levels of butylparaben were associated with increased risk of preterm delivery and lower birth weight (Geer 2017). Several studies have shown an association between higher levels of parabens and gestational diabetes and suggest the potential role in altered insulin sensitivity with high paraben exposure. A study of 241 pregnant women followed through pregnancy found a higher risk of gestational diabetes in women with higher levels of methyl-, propyl-, and butylparabens in their urine in the first and second trimesters (Bellavai 2019). 

Parabens and Obesity

Several endocrine disruptors have been associated with an increased risk of obesity, including parabens. Endocrine disruptors are associated with an increased number and size of fat cells as well as altered endocrine regulation of appetite, satiety (feeling full), food preferences, metabolism, insulin sensitivity, and energy balance (Darbe 2017). There is much more evidence for the role of endocrine disruptors like bisphenols and diethylstilbestrol in obesity, but some laboratory research shows that parabens promote adipocyte differentiation (production of fat cells) in the laboratory and alter gene expression in fat cells (Hu 2013). In her review of endocrine disruptors, Darbe emphasizes that parabens accumulate in fat cells and lead to a spiral of paraben exposure, leading to increased body fat, which stores the parabens, which leads to increased appetite and altered fat hormonal function, leading to more fat and more parabens in the system (2013). 

Parabens and Cancer

Several studies have shown that exposure to certain parabens has been associated with gene alteration (Wrobel 2014) and acceleration of breast cancer cell growth in a laboratory setting (Okubo 2001). UC Berkeley showed similar breast cancer gene alteration and breast cancer cell production with low dose butylparaben, which had previously not been considered harmful (Pan 2016). More studies are needed to definitely link cancer to paraben exposure. One of the common arguments against the ability for parabens to cause cancer is that these chemicals are eliminated from the body quickly; however, one study contradicts that claim when it showed intact and high levels of methylparaben in breast cancer tissue after surgical removal from women (Darbe 2004).

Parabens and the Environment

Many sunscreens have parabens, and unfortunately, parabens have been associated with coral reef destruction and other ecological harm (Danaovaro 2008). In May 2018, Hawaii passed legislation to ban sunscreens with oxybenzone and octinoxate – two common chemicals found in popular sunscreens associated with endocrine disruption in humans and coral reef death (Downs 2015). Could parabens (or certain parabens) be next?

 The Paraben Paradox

There is plenty of controversy surrounding use of parabens. Regulations differ by country, and recommendations differ among many different groups – even within medicine. The American Contact Dermatitis Society declares an allergen each year to increase awareness for usually new chemically created allergens to be aware of in new personal care products; however, the society declared parabens the ‘Nonallergen of the Year’ in 2019 to call attention to their low risk of allergy induction. In a 2019 review article in Dermatitis (a dermatology research journal), the authors argue that parabens are safe and inexpensive and should be used as preservatives due to their low allergy-inducing potential in cosmetics (Fransway 2019 a). The authors describe the ‘paraben paradox’ as follows: parabens “…are now among the most common biocides present in cosmetics, foods, and pharmaceuticals. This favored status has been achieved because of documented minimal toxicity, low cost, chemical inertness, and near worldwide acceptance (although that status is currently being challenged)…Without preservation, cosmetic products and pharmaceuticals rapidly become contaminated with mold, fungi, and bacteria, resulting in spoilage and increased infection risk.” The same author argues in a different article on paraben toxicology that “Haste to remove parabens from consumer products could result in their substitution with alternative, less proven, and potentially unsafe alternatives, especially given the compelling data supporting the lack of significant dermal toxicity of this important group of preservatives” (Fransway 2019 b).

In Conclusion

Parabens are inexpensive and effective preservatives found in many personal care and food products. Parabens are endocrine disruptors which alter hormonal function in the human body and have been associated with infertility, obesity, and cancer risk. Some argue that these chemicals are eliminated quickly from the body and are safe in small quantities. Others argue that the accumulation of parabens in fat cells puts overweight people at higher risk and the amount exposure and risk increases significantly in people that use multiple paraben-filled products. Further studies are needed to give definitive results; however, products are available without parabens, and you can decrease your exposure with simple steps.

How to Find Products Without Parabens

1.    Research your own products – read labels or use a database like ewg.org or thinkdirtyapp.com that lists products by toxicity and ingredients.

2.    Buy from a brand you trust like beautycounter.com.

3.    Buy from a company that screens different brands for you like credobeauty.com or follain.com.

Take Away Points

1.    Parabens are chemicals that are used as preservatives in many household products like personal care products and processed foods.

2.    Parabens are found in the majority of humans tested and throughout the body – in blood, urine, amniotic fluid, placental tissue, and breast milk.

3.    Parabens are endocrine disruptors that alter hormonal function and gene expression. 

4.    Parabens have been associated with altered reproductive function, fertility issues, obesity, and cancer.

5.    Some argue that paraben use in products is safe because small amounts are used in each product and parabens are eliminated by the body quickly.

6.    Some argue that paraben use is not safe because exposure and harm increases with multiple products and storage of parabens in fat cells puts obese people at higher risk over time.  

7.    There are alternatives to parabens for preserving products and many products available without parabens – see tips for finding paraben-free products.

More on parabens (please note that the FDA and CDC say parabens are safe):

https://www.fda.gov/cosmetics/cosmetic-ingredients/parabens-cosmetics

https://www.chemicalsafetyfacts.org/parabens/

https://www.cdc.gov/biomonitoring/Parabens_FactSheet.html

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