Preservatives in Natural Products: Parabens

The primary focus of Nature’s Pulchritude is to educate.   This post is the first in a series of in depth posts that will educate you about the various preservatives in hair and skin products, as well as their potential toxicity.

PURPOSE

Preservatives are added to cosmetics, personal care products, and food to maintain a products integrity and stability by inhibiting or reducing the growth of microorganisms such as bacteria and fungus (FDA).  Most products sold via retail sit for extended periods of time during shipping, in a warehouse, and on store shelfs that allow enough time for a product to spoil or cause microbial growth which render the product unfit for use.  This is particularly true for products that contain water, such as many conditioners and moisturizers, and other active ingredients (antioxidants and emulsifiers) that would otherwise lose their effectiveness and stability over time.

Preservatives are chosen in cosmetics based on a variety of factors which include ability to inhibit growth over a broad spectrum and method of derivation (natural vs. synthetic).  Preservatives tend to be in concentrations less than 2% of the weight of the formula, however, widespread use of potentially harmful preservatives, such as parabens, has been a great cause of concern for some scientists and consumers.  The Food, Drug, and Cosmetic Act does not grant the Food & Drug Administration the authority to regulate the use of preservatives unless it is known to be “poisonous or deleterious” (FDA).

PARABENS

Parabens are cosmetic preservatives that are esters of p-hydroxybenzoic acid that have been widely used for decades due to their overall recognition as being safe up to concentrations of 25%, which is far more than what is typically used in individual products (FDA).  Specifically known as ethylparaben, methylparaben, propylparaben, benzylparaben, isobutylparaben, and butylparaben, these preservatives came to the forefront of controversy when parabens were discovered in breast tumors by researchers in 2004.  Parabens have been found to be oestrogenic and increase progesterone (pregnancy related hormone) receptor gene expression (Darbre et al. 2004; Harvey and Darbre 2004; Harvey and Everett 2004).  The primary concern about parabens is whether or not they have the ability to accumulate and linger in human tissues despite being used in concentrations of less than 1% from multiple sources of exposure (Darbre et al. 2004).

Chemical Structure of 7 Paraben Esters

Hazards & Safety

Studies in animals have shown that parabens are “rapidly, absorbed, metabolized, and excreted” (Darbre et al. 2004). Parabens can be absorbed through intact skin which may be the result of various penetration enhancers contained in cosmetics, though various characteristics of skin also influence absorption (Darbre et al. 2004). This can be problematic because parabens are lipophilic and therefore have a propensity to bind to fatty tissues as opposed to water (Darbre et al. 2004).  Parabens are weakly oestrogenic, and the side effects of long term exposure at low-levels to “synthetic xenoestrogens” is largely unknown (Harvey and Everett 2004).  The oestrogenic interactions of parabens have been observed in humans and animals in various capacities. In humans this is believed to have an impact on the “incidence and treatment” of breast tumors (Darbre et al. 2004).

17-β-Estradiol is a naturally occurring estrogen. Diethylstilboestrol is a synthetic estrogen.

This particular study, Concentrations of parabens in human breast tumors , only assessed tissues from breast tumors as opposed to breast tissues without tumors which may or may not impact how the toxicity of parabens is assessed. The study states that the results for parabens in breast tissues falls within the broad range of concentrations for polychlorinated biphenols (PCBs) and pesticide residues (Darbre et al. 2004). Darbre was not able to determine the source of the parabens, how they entered the body (oral or dermal), or how parabens accumulated in breast tissues (via transport in body or by being topically applied to target area) which makes a definite link to causality of cancerous cells difficult (2004). Methylparaben was found in 62% of total parabens recovered from human breast tissue, which may be attributed to its widespread use or higher ability to be absorbed by the body than other parabens (Darbre et al. 2004; Yazar et al. 2010). Additionally, parabens have been shown to cause a higher frequency of hypersensitivity than other preservatives (Tomar et al. 2005).

CONCLUSIONS

There is enough evidence to be skeptical about the use of parabens in cosmetics and subsequent impact on consumers.  This validates the exploration of other preservative options, however, it cannot be stated that parabens cause cancer.  Presence of parabens in breast tumors does not mean that parabens caused the tumors, nor that topical use from cosmetics was the source of parabens in the body.  It is important to note that the chemicals used in conjunction with parabens, such as penetration enhancers, also impact their absorption by the body.  More research needs to be done to throughly assess the health impacts of parabens, however, present information supports a decrease in their use in favor of less potentially toxic preservatives.

References:

Darbre, P., Aljarrah, A., Miller, R., Coldham, N., Sauer, M., and G. Pope.  2004.  “Concentrations of parabens in human breast tissue.”  Journal of Applied Toxicology.  24: 5-13.

Harvey, P. and P. Darbre.  2004.  “Endrocrine disrupters and human health: could oestrogenic chemicals in body care cosmetics adversely affect breast cancer incidence in women?”  Journal of Applied Toxicology.  24: 167-176.

Harvey, P. and D. Everett.  2004.  “Significance fo the detertion of esters of p-hydrooxybenzoic acid (parabens) in human breast tumors.”  Journal of Applied Toxicology.  24: 1-4.

Tomar, J., Jain, V., Aggarwal, K., Dayal, S., and S. Gupta.  2005. “Contact allergies to cosmetics: testing with 52 cosmetic ingredients and personal products.” Journal of Dermatology.  32: 951-955.

U.S. FDA.  2007.  Parabens.  FDA.gov.

Yazar, K., Johnsson, S., Lind, M., Boman, A., and C. Liden.  2010.  “Preservatives and fragrance in selected consumer-available cosmetics and detergents.”  Contact Dermatitis.  64: 265-272.

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