IS METHYLPARABEN
AN ENVIRONMENTAL HAZARD?
IS METHYLPARABEN
AN ENVIRONMENTAL HAZARD?
Common problems I've encountered with "organic products" are contamination of the material with bacteria. Skin and eye infections caused by contaminated cosmetics are significant and recurrent health problems worldwide. Therefore addition of preservatives is essential in any formulation of cosmetic or bath and body product that is to be stored and used over a period of time. As a molecular biologist that specializes in bacterial pathogenesis I am intrigued by the use of parabens such as methylparaben, propylparabens, and their derivatives as antimicrobial agents. Paraben compounds occur naturally in plant sources such as blueberries, thale cress (Arabidopsis thaliana), oca (Oxalis tuberosa), wintergreen and a host of other plants. The methylparaben and propylparaben synthesized in the lab is the same compound found in nature. Methylparaben has been extensively tested in animal models and found to be non-toxic and mildly sensitizing and irritating only when applied to the skin at very high doses for a long period of time. Methylparabens and propylparaben are rapidly metabolized into the by-product p-hydroxybenzoic acid which is not stored in tissues but excreted in urine. Human studies show that p-hydroxybenzoic acid is non-toxic. However there is a debate about the carcinogenic or mutagenic effect of parabens because methylparaben has been shown associated with skin tissue following topical application of cosmetics containing parabens. So far the National Cancer Institute has not conclusively determined that methylparaben poses a significant health or cancer risk. This article is not meant to enter into the debate as to the carcinogenic properties of parabens. However, unless a clear understanding of the risk of parabens as preservatives can be established I do believe that the precautionary principle may apply. (This principle can be loosely interpreted to mean that even in the face of uncertainty if a thing might be deemed harmful it should be removed or extremely limited.) That is why companies have started to offer alternate effective antimicrobial agents to replace parabens. Parabens are used in trace amounts typically less than 0.1% of the total product.
As I was researching the environmental impact of methylparabens and propylparabens released into the air, water and soil, I was astonished to learn that these parabens are 100% biodegradable. [A biodegradable product is one that is broken down by sunlight, water, and/or living organisms into by-products which are harmless which can be re-cycled.] I suppose it makes perfect sense that parabens are biodegradable because they are after all a naturally derived product. Many other preservatives such as thimerasol are not. Methylparabens and propylparabens released into the environment are broken down by hydroxylradicals to produce p-hydroxybenzoic acid. The p-hydroxybenzoic acid by-product is found in nature as well and found in such things as carrots, olives, cucumbers, strawberries and ylang ylang to name just a few. The p-hydroxybenzoic acid paraben by-product is itself an anti-microbial agent and both paraben and p-hydroxybenzoic acid are a food source for some bacteria. For example a certain type of bacterium called Enterobacter metabolizes methylparaben, uses it as a sole carbon-source and energy-source; breaking parabens down into phenol. The toxic phenol by-product is then removed from the environment by certain species of Pseudomonas which can use phenol as a nutrient. In addition some species of Pseudomonas can actually utilize propylparaben as its nutrient and break it down into completely harmless carbon-based compounds.
I know that was a lot of science but the bottom line is, Methylparaben or propylparaben is not recalcitrant and can be removed from the environment by cooperative bacterial metabolism. Furthermore methylparabens have not been shown to be concentrated in the tissues of aquatic organisms. This contrasts significantly with another commonly used antimicrobial, thimerosal, which is a neurotoxin, (Used in vaccines and blamed for autism in young children). Thimerosal is totally synthetic and toxic to aquatic organisms. Both methylparaben and propylparaben have no known negative-environmental impact and both compounds are very effective at protecting consumers from the adverse consequences of bacterial contamination of cosmetics. As a scientist concerned with chemical contaminates of the earth, I sincerely hope that science can conclusively prove methylparaben and propylparabens have no detrimental affect on humans because it is truly "earth friendly".
Okay, so what do manufacturers of organic bath and body products use as antimicrobials? One of the organic lines that we carry uses the antimicrobial sodium benzoate. Sodium benzoate is the same as benzoic acid except it contains a sodium (Na2+) side group which makes it more soluble in water. Benzoic acid is a naturally occurring product found in most berries and other plants such as gum benozin. Would you believe that benzoic acid is similar to p-hydoxybenzoic acid, the by-product of methylparaben? Here's how! The compound p-hydroxybenzoic acid is a phenolic derivative of benzoic acid. Remember that p-hydroxybenzoic acid is non-toxic and naturally occurs in several fruits, vegetables and plants. Take a look at the pictures below which compares the chemical structures of methylparaben and propylparaben, p-hydroxybenzoic acid, and sodium benzoate. These compounds are similar in structure; only the side chains vary. Both groups of compounds act as antimicrobials and all are 100% biodegradable. Benzoic acid is not believed to be carcinogenic and the evidence against methylparaben is extremely weak.
Some of the products we carry on our shelves have been re-formulated by manufacturers over the last four years to remove or reduce the amounts of questionable preservatives. So I've seen evidence that manufacturers are responding to the challenge put-forth by consumers for more eco-friendly and safe products.
Written by: Dr. M.E. Scott
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