Three chemicals used in household products—diethylene glycol monobutyl ether (DEGBE), 2-mercaptopyridine-N-oxide sodium (MPOS), zinc dibenzyldithiocarbamate (ZBEC)—were evaluated for their skin sensitization potency in a modified guinea pig maximization test (GPMT) and non-radioactive murine local lymph-node assay (LLNA). In the GPMT, DEGBE failed to elicit a positive skin reaction even at maximum concentrations for the induction and elicitation procedures, whereas MPOS and ZBEC gave positive reactions. MPOS-induced animals cross-reacted to its analogous biocide, zinc pyrithione. In the LLNA, however, all three agents gave negative results. The results suggest that MPOS and ZBEC possess the intrinsic ability to cause skin sensitization, but the potency is not so high as to induce skin sensitization in mice through dermal exposure alone.
To control household products containing harmful substances, Japanese law sets an upper limit (i.e., under 10%) on the content of hydrochloric acid (HCl) and sulfuric acid (H2SO4) in commercially available acidic detergents for use in homes. Acid-base titration is the officially authorized method of determining whether these acids are within set limits. However, in cases of detergents containing organic acids and an inorganic acid in addition to HCl and H2SO4 these acids also consume the alkaline reagent during titration. For this reason, the present study applied ion chromatography (IC) and capillary electrophoresis (CE) to the determination of the two regulated acids. CE analysis of the two regulated acids following a large dilution (×10,000) of acidic detergents showed no interference from sample matrixes such as the surface-active agent. Rather it was found that citric and malic acids interfered in the determination of the two regulated acids in IC analysis. Organic acids other than citric and malic acids did not affect the quantification of the two regulated acids in either IC or CE analysis.