Cosmetics’ are defined as any substance or preparation intended to
be placed in contact with the various external parts of the human
body (epidermis, hair system, nails, lips and external genital organs)
or with the teeth and the mucous membranes of the oral cavity with
a view exclusively or mainly to cleaning them, perfuming them,
changing their appearance and/or correcting body odours and/or
protecting them or keeping them in good condition in EU [1]. It is
very important to ensure the safety of cosmetics, and cosmetic companies
have made great efforts to improve this safety. Despite their
efforts, various types of adverse events from simple skin irritation to
severe dermatitis have been reported [2–4]. The safety of cosmetics
can be evaluated at various levels such as through in vitro, animal
and human experiments using specialized methods [5–16]. However,
the cosmetics safety assessment at the cellular or animal level could
not clearly reflect the safety in the human skin. The adequacy of
these tests is debatable, and safety assessment should therefore be
performed at the human level [17–19]. The most important step is to
evaluate skin toxicity such as the potential of cosmetics to cause irritation
and sensitization. The human patch test is a useful method to
test primary irritation in the human body caused by direct contact
with the skin [14–16, 20].