Parabens

Parabens are preservatives used in a wide variety of personal care products and foods to prevent the growth of microbes. These endocrine-disrupting chemicals can be absorbed through skin, blood and the digestive system.[1] 

FOUND IN: Shampoos, conditioners, lotions, facial and shower cleansers and scrubs

WHAT TO LOOK FOR ON THE LABEL:  Ethylparaben, butylparaben, methylparaben, propylparaben, isobutylparaben, isopropylparaben, other ingredients ending in –paraben

WHAT ARE PARABENS? Parabens are actually several distinct chemicals with a similar molecular structure. Several are common in a wide array cosmetic and personal care products: ethylparaben, butylparaben, isobutylparaben, isopropylparaben, methylparaben and propylparaben.MORE...

 Methylparaben and propylparaben are the most common of these.

Parabens are most common in personal care products that contain significant amounts of water such as shampoos, conditioners, lotions and facial and shower cleansers and scrubs because they discourage the growth of microbes. While the Cosmetic Ingredient Review [link to regulation section] recommends concentration limits for single (up to 0.4%) and total paraben concentrations (up to 0.8%) in a single product, these recommendations do not account for exposure to parabens from several products by a single individual.[3]

Parabens are found in nearly all urine samples from U.S. adults regardless of ethnic, socioeconomic or geographic backgrounds.[4] In one biomonitoring study, adolescents and adult females had higher levels of methylparaben and propylparaben in their urine than did males of similar ages.[5]

A 2004 UK study detected traces of five parabens in the breast tumors of 19 out of 20 women studied.[6] This small study does not prove a causal relationship between parabens and breast cancer, but it is important because it detected the presence of intact parabens—unaltered by the body’s metabolism—which is an indication of the chemical’s ability to penetrate skin and remain in breast tissue. A more recent study found higher levels of one paraben, n-propylparaben, in the axilla quadrant of the breast (the area nearest the underarm).[7] This is the region in which the highest proportion of breast tumors is found, although paraben concentration in the tissue samples was not related to location of breast tumors in individual women.

Parabens are not water soluble and can penetrate the skin. As a result, repeated application of a product or multiple products containing parabens could mean almost continuous exposure.[8] The ubiquity of parabens in personal care products makes this a reasonable scenario.

HEALTH CONCERNS: Endocrine disruption, cancer, developmental and reproductive toxicity MORE...

Endocrine disruption: Parabens are potential endocrine disruptors due to their ability to mimic estrogen.[9] In cell studies, parabens have been found to weakly bind to estrogen receptors.[10] Studies demonstrate that at sufficient concentrations, parabens can increase cell proliferation in human breast cancer MCF-7 cells, which are often used as a sensitive measure of estrogenic activity.[11] In MCF-7 cells, isopropyl- and isobutyl parabens have the most potent of proliferative potency, but they are around 170,000 times lower than estradiol.[12],[13]

 The so-called “long chain” parabens[14]  (butylparaben and its alternative form, isobutylparaben and  isopropylparaben and propylparaben) have the strongest estrogenic activity among those widely used in personal care products. A study of prenatal isobutylparaben exposure in rats demonstrated increased uterus weight and uterine sensitivity to estrogen in the offspring.[15] Ethylparaben showed lower levels of estrogenic activity and methylparaben shows almost no estrogen activity.[16] In addition to direct estrogenic effects, parabens can block androgens (for example, testosterone)[17] and inhibit enzymes that metabolize estrogen.[18]

The Endocrine Disruption Exchange includes methylparaben,[19] ethylparaben,[20] propylparaben,[21] butylparaben,[22] isopropylparaben,[23] isobutylparaben[24] as endocrine disruptors due the multiple endocrine effects described above.

Skin Cancer: Applying personal care product containing parabens—especially methylparaben—can lead to UV-induced damage of skin cells and disruption of cell proliferation (cell growth rate).[25],[26]  Daily application, in particular, can lead to increased concentrations of methylparaben because it is not completely metabolized.[27] Parabens combined with other estrogenic chemicals may potentially influence the development of malignant melanoma, one form of skin cancer, through their estrogenic and genotoxic activites.[28]

Developmental and Reproductive toxicity: Propyl and butyl parabens appear to reduce sperm production[29],[30] and lead to reduced testosterone levels,[31] while methyl- and ethyl-parabens do not affect sperm production. These effects appear to be dose-dependent.[32] In addition, one study found that maternal exposure to butylparaben during gestation and lactation alters the development of the reproductive organs and sperm production.[33] In general, propyl- and butylparabens, specifically, appear disrupt male reproductive system and affect the reproductive organs.[34],[35] This is consistent with their estrogenic activity noted above.

Laboratory evidence suggests that maternal exposure to isobutylparaben during gestation can lead to anxiety and behavioral changes in offspring.[36],[37]

VULNERABLE POPULATIONS: Pregnant women and young children

REGULATIONS: Some forms of parabens are banned in Denmark (propyl and butyl paraben, their isoforms and their salts) in cosmetics products for children up to 3 years.[2]

HOW TO AVOID: Look for products labeled “paraben-free” and read ingredient lists on labels to avoid products with parabens. Many natural and organic cosmetics manufacturers have found effective alternatives to parabens to prevent microbial growth in personal care products. Some companies have created preservative-free products that have shorter shelf lives than conventional products (six months to a year). 

References

[1] Gray, J. State of the Evidence: The Connection between Breast Cancer and the Environment, 2008.

[2] Danish Ministry of the Environment-Environmental Protection Agency. Statutory order on restriction on import, sale and use of certain parabens in cosmetic products for children under 3 years. Available online: http://eng.mst.dk/media/mst/Attachments/Engelskparabenbekendtgrelse.pdf August 12, 2014.

[3] Cosmetic Ingredient Review. Final amended report on the safety assessment of methylparaben, ethylparaben, propylparaben, isopropylparaben, butylparaben, isobutylparaben, and benzyparaben as used in cosmetic products. International Journal of Toxicology, vol. 27, no. 4, pp 1-82, 2008. Available online: http://www.cir-safety.org/sites/default/files/paraben_build.pdf August 12, 2014.

[4] Ye X., et al., Parabens as urinary biomarkers of exposure in humans. Environmental Health Perspectives, vol. 114, pp 1843-1846, 2006.

[5] Calafat AM., et al., Urinary concentrations of four parabens in the U.S. Population: NHANES 2005-2006. Environ Health Persp, vol. 118, no. 5, pp 679–685, 2010.

[6] Darbre PD, et al.,  Concentrations of parabens in human breast tumors. Journal of Applied Toxicology, vol.  24, pp 5-13, 2004.

[7] Barr L., et al., Measurement of paraben concentrations in human breast tissue at serial locations across the breast from axilla to sternum. J Appl Toxicol, vol. 32, no. 3, pp 219–232, 2012.

[8] Prusakiewicz JJ., et al., Parabens inhibit human skin estrogen sulfotransferase activity: Possible link to paraben estrogenic effects. Toxicology, vol. 232, pp 248-56, 2007.

[9] Darbre PD., et al., Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks. Journal of Applied Toxicology, 2008.

[10] Prusakiewicz JJ., et al., Parabens inhibit human skin estrogen sulfotransferase activity: Possible link to paraben estrogenic effects. Toxicology, vol. 232, pp 248-56, 2007.

[11] Darbre PD., et a., Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks. Journal of Applied Toxicology, 2008.

[12] Golden R., et al., A review of the endocrine activity of parabens and implications for potential risks to human health. Critical Reviews in Toxicology, vol. 35, pp 435-58, 2005.

[13] Dabre PD., et al., Oestrogenic activity of isobutylparaben in vitro and in vivo. Journal of Applied Toxicology, vol. 22, no. 4, pp 219-26. 2002.

[14] Oishi S., Effects of butylparaben on the male reproductive system in rats. Toxicology and Industrial Health, vol 17, pp 31-9, 2001.

[15] Kawaguchi M., et al., Maternal isobutyl-paraben exposure decreased the plasma corticosterone level in dams and sensitivity to estrogen in female offspring rats. J. Vet. Med. Sci., vol. 71, no. 8, pp 1027-33, 2009.

[16] Oishi S., Effects of butylparaben on the male reproductive system in rats. Toxicology and Industrial Health, vol 17, pp 31-9, 2001.

[17] Darbre PD., et a., Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks. Journal of Applied Toxicology, 2008.

[18] Prusakiewicz JJ., et al., Parabens inhibit human skin estrogen sulfotransferase activity: Possible link to paraben estrogenic effects. Toxicology, vol. 232, pp 248-56, 2007.

[19] The Endocrine Disruption Exchange (TEDX). Methyl paraben. Available online: http://endocrinedisruption.org/popup-chemical-details?chemid=667 August 7, 2014.

[20] The Endocrine Disruption Exchange (TEDX). Ethyl paraben. Available online: http://endocrinedisruption.org/popup-chemical-details?chemid=573 August 7, 2014.

[21] The Endocrine Disruption Exchange (TEDX). Propyl paraben. Available online: http://endocrinedisruption.org/popup-chemical-details?chemid=795 August 7, 2014.

[22] The Endocrine Disruption Exchange (TEDX). Butyl paraben. Available online:

http://endocrinedisruption.org/popup-chemical-details?chemid=441 August 7, 2014.

[23] The Endocrine Disruption Exchange (TEDX). Isopropyl paraben. Available online: http://endocrinedisruption.org/popup-chemical-details?chemid=916 August 7, 2014.

[24] The Endocrine Disruption Exchange (TEDX). Isobutyl paraben. Available online: http://endocrinedisruption.org/popup-chemical-details?chemid=915 August 7, 2014.

[25] Darbre PD., et a., Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks. Journal of Applied Toxicology, 2008.

[26] Ishiwatari S., et al., Effects of methyl paraben on skin keratinocytes. J. Appl. Toxicol, vol 27, pp 1-9, 2007.

[27] Ishiwatari S., et al., Effects of methyl paraben on skin keratinocytes. J. Appl. Toxicol, vol 27, pp 1-9, 2007.

[28] Darbre PD., et a., Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase and human exposure, and discussion of potential human health risks. Journal of Applied Toxicology, 2008.

[29] Oishi S.,Lack of spermatotoxic effects of methyl and ethyl esters of p-hydroxybenzoic acid in rats. Food and Chemical Toxicology, vol. 42, pp 1845-49, 2004.

[30] Taxvig C., et al., Do parabens have the ability to interfere with steroidogenesis? Toxicological Sciences, vol. 106, no. 1, pp 206-13, 2008.

[31] Taxvig C., et al., Do parabens have the ability to interfere with steroidogenesis? Toxicological Sciences, vol. 106, no. 1, pp 206-13, 2008.

[32] Oishi S., Effects of butylparaben on the male reproductive system in rats. Toxicology and Industrial Health, vol 17, pp 31-9, 2001.

[33] Kang KS., et al., Decreased sperm number and motile activity on the F1 offspring maternally exposed to butyl p-hydroxybenzoic acid (butyl paraben). J. Vet. Med. Sci., vol. 64, no. 3, pp 227-35, 2002.

[34] Oishi S., Effects of butylparaben on the male reproductive system in rats. Toxicology and Industrial Health, vol 17, pp 31-9, 2001.

[35] Taxvig C., et al., Do parabens have the ability to interfere with steroidogenesis? Toxicological Sciences, vol. 106, no. 1, pp 206-13, 2008.

[36] Kawaguchi M., et al., Maternal isobutyl-paraben exposure decreased the plasma corticosterone level in dams and sensitivity to estrogen in female offspring rats. J. Vet. Med. Sci., vol. 71, no. 8, pp 1027-33, 2009.

[37] Kawaguchi M., et al., Maternal isobutyl-paraben exposure alters anxiety and passive avoidance test performance in adult male rats. Neuroscience Research, vol. 65, no. 2, pp 136-40, 2009.