Parabens: food preservatives and consumer safety

摘要

Preservatives are particularly important among the generally utilized food additives. Their main purpose is to extend the shelf-life of the food products through slowing down the rotting process caused by the presence of bacteria. Among the numerous preservatives used for food p-hydroxybenzoic acid esters (parabens) and their sodium salts are also allowed. Parabens were synthesized in 1924 as an alternative preservative for salicylic and benzoic acids and they quickly gained acceptance not only in food processing but also in the pharmaceutical and cosmetic industries. Among the most commonly used parabens are the methyl, ethyl and propyl (and isopropyls) along with their sodium salts. What determined the popularity of parabens as preservatives was their powerful bactericidal and fungicidal properties, along with their resistance to the high temperatures used in food processing, and their ability to be combined with other preservatives (most often with sorbates and benzoates): such combinations allow for attaining the desired technological effect in smaller doses of the specific substances than when only one of them is used. Also significant was the general opinion that parabens did not affect the health of the consumers, which was supported by research on the metabolism and lack of their traces in the human body as well as their lack of accumulation in the tissues of experimental dogs. Nevertheless the results of investigations conducted on animals and people published in the first decade of the twentieth first century cast doubt on the safety of parabens as preservatives. From the results of research in vitro and in vivo it was concluded these compounds could modify the hormonal economy of the body through binding themselves with estrogen receptors. Despite low estrogen activity they were counted among factors that could act as endocrine disruptors (EDs), among which also belong dichlorodiphenyltrichloroethanes (DDT), dioxins, polychlorinated biphenyls (PCB), phthalates, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The enumerated compounds are also called xenoestrogens, in other words estrogen substances that are created as a result of human actions. Alongside fito- and micoestrogens they are one of the three groups of estrogen compounds occurring in the environment. This was confirmed by research conducted on rats proposed by the Scientific Committee on Food (SCF), an advisory organ for the European Commission (EC), from 2003 incorporated as a part of the European Food Safety Authority (EFSA). On the basis of the results of this research, EFSA published a report in which it presented its opinion on the safety of using parabens. The acceptable daily intake (ADI) was established at 0-10 mg/kg m.c. only for sums of methanol and ethanol ester p-hydroxybenzoic acid as well as their sodium salts. The propyl esters of p-hydroxybenzoic acid were not taken into account in the ADI of this group since there was no observable adverse effect level (NOAEL). Simultaneously, a dose of 10 mg/kg was designated as the lowest observed adverse effect level (LOEAL) for the propyl ester of p-hydroxybenzoic acid. In the conclusion of the EC report it was stated that the danger for consumers from the use of parabens in food was not adequately evaluated. For this reason propyl esters of p-hydroxybenzoic acid and its sodium salts were removed from the list food additives and, in addition, the remaining esters were also banned from use in liquid dietary supplements.