Propylparaben is the propyl ester of p-hydroxybenzoic acid, occurs as a natural substance found in many plants and some insects, although it is manufactured synthetically for use in cosmetics, pharmaceuticals and foods, according to Wikipedia.
It is used as a preservative for its anti-fungal and anti-microbial properties to extend the shelf life of beauty and cosmetic products. It is considered non-toxic, non-sensitizing and non-irritating at .05 to 1% concentrations. As a food additive, it has the E number E216
Although parabens (the group of chemicals in which propylparaben belongs) are generally considered safe when used in low percentages (.04% – .08%), many studies have found a link between parabens and breast cancer. According to the CIR Expert Panel, however, “the available acute, subchronic, and chronic toxicity tests, using a range of exposure routes, demonstrate a low order of parabens’ toxicity at concentrations that would be used in cosmetics” (source). After testing different levels of exposure to parabens in women, men, and children, the CIR Expert Panel found that these “determinations are conservative and likely represent an overestimate of the possibility of an adverse effect (e.g., use concentrations may be lower, penetration may be less) and support the safety of cosmetic products in which parabens preservatives are used.”
Ultimately, the cosmetics industry has found the low levels of parabens in cosmetics to be safe and the connection between parabens and breast cancer to be weak. The FDA (which has given Propylparaben its GRAS rating) finds that although parabens can mimic estrogen, the actual effects of this low level of activity on the body do not cause cancer in a higher incidence than naturally occurring estrogen. Nonetheless, many paraben-free products are being created to avoid the possible dangers of Propylparaben and other paraben-based preservatives.
However. In a 2004 study published by the Journal of Applied Toxicology, 18 of 20 malignant breast tumors showed high concentrations of parabens, which are known to mimic estrogen in the body and affect the growth of breast tissue. Dr. Darbre, one of the chief scientists on the study, acknowledged that “One would expect tumours to occur evenly, with 20 per cent arising in each of the five areas of the breast … But these results help explain why up to 60 per cent of all breast tumours are found in just one-fifth of the breast – the upper-outer quadrant, nearest the underarm” (source). Not all deodorants contain parabens; however, many beauty products in addition to deodorant contain parabens, including face cream, body lotions, cleansers and shampoos.
The Human Toxome Project, a study being conducted by the Environmental Working Group, found that 26 out of the 28 people tested were found to have Propylparaben in their urine, showing its widespread usage in products, and its ability to travel through the body as well as stay in the system. The EWG gives propylparaben a safety rating of 70% for use in formulas.
Truth in Aging, https://www.truthinaging.com/ingredients/propylparaben