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Pure Appl. Chem., Vol. 70, No. 9, pp. 1847-1853, 1998
Natural and anthropogenic environmental
Oestrogenic potency of nonylphenol in vivo - a case study to evaluate the relevance of human non-occupational exposure
S. Müller and C. Schlatter
Introduction: 4-Nonylphenol (NP) is an alkylphenolic compound that is mainly used as an intermediate in the chemical manufacturing industry (Structure and physico-chemical data are given in Figure 1). NP is used directly for example to label tax-favored light fuel oil, as an preservative agent, in the tanning industry, etc.. In the form of NP-phosphites, it finds use as an co-stabilizer and antioxidant in various polymers like rubber and plastics; in the form of NP metal salts it is used as a stabilizer in PVC (ref. 1). But the predominant use of NP is in the form of NP polyethoxylates (NPnEO) with variable ethoxylate chain length as emulsifying, dispersing, wetting and foaming agent, e.g. in paints, in cosmetics, in agrochemicals, in textile manufacturing, in metal finishing, as spermicide, and as additive in lubricating oils (ref. 1, 2). In 1994, the annual use of NP was estimated to be 78497 tons/year solely in Europe (ref. 3).
Fig. 1. Structure and physico-chemical properties of 4-nonylphenol.
The oestrogenic properties of p-alkylated phenolic compounds were recognized as early as 1938 (ref. 4, 5). NP binds to the oestrogen receptor and exerts oestrogenic actions in vivo and in vitro (ref. 6, 7, 8, 9).
Human exposure routes are diverse. Exposure via contaminated foods and drinking water, but also via dermal absorption after the application of NP-containing products, or via inhalation could occur (ref. 10, 11, 12). The question arises whether the human exposure to NP and its derivatives could result in blood and organ concentrations great enough to elicit oestrogenic effects.
In this study, we assess the oestrogenic potency of NP and perform a risk calculation for non-occupationally exposed humans. This calculation is based on the estimated daily intake of NP, the relative oestrogenic potency as evaluated from different in vivo and in vitro systems, the pharmacokinetic behavior in humans, and comparison of the oestrogenic burden in blood and organs with the phytoestrogen genistein and 17b-estradiol, respectively.
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