Characterization of heavy users of skin care products among Norwegian women from 2003 to 2011
The use of personal care products (PCPs), such as skin care products, deodorant and tooth paste are currently a part of many people’s daily hygiene routine. Some of the ingredients in PCPs have been identified as endocrine disruptors (EDs), i.e. molecules that are able to affect and interfere with the hormonal system of humans or wildlife. After dermal application of PCPs, possible EDs are easily absorbed by the epidermis into the subcutaneous tissue and the central blood circulation and concern has therefore been raised whether the use of PCPs can affect human health.
Of possible EDs in PCPs, frequently mentioned are ultraviolet-filters (UV-filters), triclosan, phthalates and parabens [1]. Some of the UV-filters found in sunscreen products show endocrine disruptive activity in vitro and/or in vivo [2]. Triclosan has been a preservative in PCPs since the late 1960s, and has been detected in human fluids like urine, serum and breast milk [3]. Triclosan can bind to both the estrogen and the androgen receptor, but in vitro and in vivo consequences of this have been diverse [3]. Phthalates, also called plasticizers, are a group of molecules increasing the softness of plastics. Phthalates can appear in fragrances and hair products as fixatives [4], but also leak from packaging material into the product. Their endocrine disrupting mechanism has been suggested to be interference with testosterone production or the testosterone action [1]. Parabens have been one of the most frequently used preservatives in PCPs since the beginning of the 20th century [5]. Parabens are able to bind to the estrogen receptor [6], and the affinity increases with the length of the alkyl chain. Long chained parabens (isopropylparaben, isobutylparaben, phenylparaben, benzylparaben and pentylparaben) have been banned in PCPs within the European Union (EU) during the last years, and the concentrations for propyl- and butylparaben in PCPs have recently been reduced [7].
In our recent study [8], we found elevated concentrations of methylparaben (MP) in blood samples from Norwegian women frequently using skin care products (defined as creams and lotions for skin care), indicating that everyday use may keep the concentration of parabens continuously high in blood, despite a short half-life. A recent Swedish study found a correlation between urinary concentrations of parabens and the use of PCPs, and a US study found a correlation between urinary concentrations of some phenols and phthalate metabolites and the use of PCPs in both adults and children, suggesting that the use of PCPs is an important source of exposure to several EDs [4, 9].
PCPs often contain a complex mixture of EDs, and as there is limited knowledge about the collective effect of these chemicals on human health, population studies addressing the association between PCP use and hormonally related diseases are needed. As a first step in this process, it is important to characterize the heavy users of these products.
Between 2003 and 2011, more than 100 000 women in the Norwegian Women and Cancer (NOWAC) study answered questionnaires covering a large number of lifestyle factors including the use of skin care products. The aim of this study was to describe and compare lifestyle characteristics between heavy users of skin care products and non-users. To the best of our knowledge, published studies on use of skin care products have not involved a sample of this size, nor a characterization of the participants regarding life style characteristics and endocrine events in a woman’s life such as menarche, pregnancy, breastfeeding and menopause, which are important factors for hormonally related diseases.