Reactions of sunscreen agents, octyl dimethyl-p-aminobenzoate (ODPABA) and octyl-p-methoxycinnamate (OMC), with hypochlorite in aqueous solution were investigated under the conditions that simulate swimming pool disinfection sites. Chlorination byproducts were determined by GC-MS. At a concentration of 9 µM, ODPABA reacted rapidly with free chlorine in the buffered solution at pH 7.0, OMC reacted with hypochlorite reasonably slowly under the same condition. ODPABA and OMC produced chlorine-substituted compounds as intermediates, which were decomposed to cleavaged products of ester-bond during the aqueous chlorination process. The chlorination intermediates of OMC exhibited weak mutagenic on Salmonella typhimurium TA100 strain without the S9 mix. The extent of the reactions depended on the chlorine dose, solution pH, and compound structures.

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tyl phthalate (DBP). 1)Some phthalate diesters induce testicular toxicity in the male reproductive tract. Jobling et al. showed that DBP binds to the estrogen receptor, displaces its natural ligand, and then acts as an estrogen antagonist.2) In addition, mono-n-butyl phthalate (MBuP) adversely affects development of the reproductive system in male rats.3) DEHP is a peroxisome proliferator that induces tumors in the rodent liver, and this effect is probably not exerted by DEHP itself but by one or more of its metabolites. 4)Phthalate diesters are metabolized to monoesters by hydrolases in many tissues, such as the pancreas, intestine, and blood.5-7) Generally orally ingested dialkyl phthalates are hydrolyzed by esterases in the wall of the small intestine and pancreatic lipases and not by gut flora. Absorption occurs almost entirely as the corresponding monoesters.5) Human saliva is a matrix of inorganic compounds, saliva proteins such as lingual lipase and α-amylase, oral flora, and cell debris. 8) However, to the best of our knowledge there are no reports concerning enzymatic hydrolysis of phthalate diesters in human saliva, except for our previous paper.9) The present work was therefore designed to characterize human salivary esterase in enzymatic hydrolysis of phthalate esters. These findings provide the information that will be required in considering the human health effects of phthalate esters. MATERIALS AND METHODSChemicals and Glassware ---Monoethyl phthalate (MEP), diethyl phthalate (DEP), and DEHP were purchased from Wako Pure Chemical Industries. (Osaka, Japan) and MBuP, mono-n-hexyl phthalate (MHxP), mono-2-ethylhexyl phthalate (MEHP), monobenzyl phthalate (MBeP), and di-n-hexyl phEnzymatic hydrolysis of phthalate esters in human saliva was investigated to characterize salivary esterase in the formation of monoesters from their diesters. The monoesters formed were analyzed by GC/ MS after incubation of phthalate diesters in the saliva. Hydrolytic activity in the supernatant obtained by centrifugation of the saliva at 1350 × g was equivalent to that in whole saliva, and the activity was inhibited by the addition of denaturing protein. The hydrolytic activity was dependent on the protein concentration in the supernatant. The optimum temperature and pH of the hydrolysis was 50°C and 8.2, respectively. In addition, the 80% acetone powder of the supernatant showed high substrate specificity for straight-chain alkyl group of phthalate diesters, especially the butyl group, whereas almost no specificity was seen for the 2-ethylhexyl and benzyl groups. These results indicate that not the oral flora but salivary esterase, such as lingual lipase, is involved in phthalate monoester formation from the diesters in human saliva, and do not act on the hydrolysis of monoester.

Human volunteers chewed polyvinyl chloride (PVC) products under controlled conditions for 60 min (four consecutive periods of 15 min), and then the amount of diisononyl phthalate (DINP) migration into the saliva was determined by HPLC. The PVC products consisted of a molded plate containing added DINP (500 mg/g) and five types of commercial toy containing 160-583 mg/g DINP (mean value 372 mg/g). The DINP migration rates ranged from 3.8 to 32.6 µg/cm 2 / hr (mean value 16.4 µg/cm 2 /hr). The DINP contents in the toy products did not correlate with the amount of in vivo migration. The DINP migration rates during the last 15-min period (45-60 min) decreased by 38-75% compared with the first session (0-15 min). In addition, in vitro DINP migration rates from the PVC products into saliva simulant during 15 min of rotary shaking were about 3.6-4.1-fold higher than the rates in vivo over 60 min, and remained essentially fixed for each sample.