Parabens and its derivatives are a widely used group of preservatives in personal care and cosmetic products. Preservatives are designed to prevent the growth of bacteria, moulds and yeast which would damage the product and potentially harm us if we ingested it. It is a safety measure as well as one dealing with maintaining quality to add ingredients like parabens to products.
Cosmetics and food are rich sources of nutrients for a range of micro-organisms and their control is essential if we are to ensure the product remains safe to use over its shelf-life. Preservatives help to maintain quality over their period of use and unless we store products in the freezer we are never really able to be free of them. Some preservatives are only found in personal care products and ones such group are the parabens type. They are allowed for use in foods up to 0.1% and are strictly regulated even for cosmetics simply because they are not to be ingested. It is thought based on some old evidence that adult humans consume on a daily average about 4 to 6 mg/kg (Elder, 1984).
Parabens is a collective name for a group of preservatives, the alkyl esters p-hydroxybenzoic acid often found on an ingredients label. They include ethylparaben, butylparaben, methylparaben, propylparaben, isobutylparaben, isopropylparaben amongst others and all have the link to the paraben chemical structure. Benzoic acid is a common enough preservative in foods and so parabens derivatives have similar chemical properties to this oft used material. Immediately after the First World War, the hydroxybenzoic acid derivatives began to be explored as antimicrobials (Murrell and Vincent, 1950) and have been in use continuously since then. It is also common to see one or a number of these including other preservatives in the formulation giving as a wide a spectrum of activity against a variety of micro-organisms as possible. Incidentally, it is the law to quote each ingredient in the order of amount on the label so that we, the public are fully aware of what is contained in a product.
Safety of Parabens
There is a tremendous amount of media coverage of ingredients generally and chemicals like parabens do not escape this scrutiny. The amounts used are so small that safety limits are not exceeded and so there is no legitimate reason not to use a product containing parabens. It is also worth commenting on the fact that p-hydroxybenzoic acid occurs as a naturally occurring ingredient in raspberries and some other fruits. It may explain some of the preservative action in part of particular juices including cranberry juice.
However, there is no shortage of studies examining the safety of these preservatives.
Parabens are types of phytoestrogens which means they have hormonal activity which would have an effect in humans if their levels were significant enough to have an impact. Phytoestrogens generally mimic the main natural estrogen 17ß-estradiol by binding to the estrogen receptor and influencing the expression of various estrogen-dependent genes. This is an important phenomenon and has been linked to a progressive decline in human male reproduction health and fertility for example (Auger et al., 1995; Carlsen et al., 1192; 1995) and was further investigated in a series of studies associated with breast cancer (Routledge et al., 1998; Darbre et al., 2002, 2003). There are some excellent reviews which cover the body of work concerning various parabens and it is worth accessing these (Witorsch and Thomas, 2010; Błędzka et al., 2014).
The general conclusion from the research to date is that there is really not enough levels of ingestion to warrant the issues that surround parabens. Each component has been assessed to varying degrees and does show weak estrogenic activity ‘in vivo’ but they have never been shown to have an adverse effect in humans.
Auger, J., Kunstmann, J. M., Czyglik, F., and Jouannet, P. (1995). Decline in semen quality among fertile men in Paris during the past 20 years. N. Engl. J. Med. 332, pp. 281–285
Błędzka, D., Gromadzińska, J., & Wąsowicz, W. (2014). Parabens. From environmental studies to human health. Environment International, 67, pp. 27-42
Carlsen, E., Giwercman, A., Keiding, N., and Skakkebaek, N. E. (1995). Declining semen quality and increasing incidence of testicular cancer: Is there a common cause? Environ. Health Perspect. 103(Suppl 7), pp. 137–139
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Darbre, P.D., Byford, J.R., Shaw, L.E., Hall, S., Coldham, N.G., Pope, G.S., Sauer, M.J. (2003) Oestrogenic activity of benzylparaben. J. Appl. Toxicol. 23 pp. 43–51
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Murrell, W.G., Vincent, J.M. (1950) The 4-hydroxybenzoic acid esters and related compounds. 4. The bacteriostatic action of 4- hydrozybenzoic acid n-alkyl esters. J. Soc. Chem. Ind. 69 pp. 109–113.
Routledge, E.J., Parker, J., Odum, J., Ashby, J., Sumpter, J.P. (1998) Some alkyl hydroxy benzoate preservatives (parabens) are estrogenic. Toxicol. Appl. Pharmacol. 153 pp. 12–19
Witorsch, R. J., & Thomas, J. A. (2010). Personal care products and endocrine disruption: a critical review of the literature. Critical reviews in toxicology, 40(sup3), pp. 1-30