Skin sensitization is an extremely important risk factor for occupational health and safety, and it would be desirable to set health‐based exposure limits (HBELs) for the quantitative risk assessment (QRA) based on the skin sensitizing potencies of chemical. We attempted to set acceptable surface limits (ASLs) as HBELs for skin sensitizers in the workplace based on the local lymph node assay (LLNA): BrdU‐ELISA EC1.6 values. To calculate the ASLs, a safety assessment factor (SAF)interspecies value of 6, based on the EC1.6 values/human repeat insult patch test (HRIPT) NOEL ratios, a SAFinterindividual value of 10, and a SAFfrequency/duration value of 3 were applied, referring to previous literatures on SAFs for skin sensitization QRA, and the composite SAF was calculated as 180. The ASLs (mg/100 cm2) derived thus for 33 chemicals ranged from 0.001 to 10.417. Comparison of the ranges with known human sensitization potency classes and GHS subcategories revealed that use of GHS Category 1A chemicals needs to be controlled to ensure surface residue levels of less than 1 mg/100 cm2. To minimize sensitization risks, a quantitative sensitization risk assessment method for chemicals and appropriate risk management are necessary. This report provides a potentially useful ASL‐based method of managing sensitization risk derived from LLNA: BrdU‐ELISA EC1.6 values, comparison of the ASLs and known human sensitization potency data showed that GHS subcategorization results would be a primary information notifying ASL ranges to be required for minimizing the sensitization risk.

Background: Serious cases of allergic contact dermatitis (ACD) caused by exposure to 3,5,6-tetrachloro-4-(methylsulfonyl)pyridine (TCMSP; CAS no. 13108-52-6) used as an antimicrobial agent for desk mats have been reported in Japan.Objective: A quantitative risk assessment (QRA) of TCMSP contained in desk mats was performed retrospectively. Materials and Methods:A local lymph node assay (LLNA): BrdU-ELISA was conducted to determine a reliable EC1.6 value for TCMSP. The acceptable exposure level (AEL) for TCMSP was derived from the EC1.6 value by applying sensitization assessment factors (SAFs). The exposure level was estimated based on the assumption referring to the use conditions of thiabendazole in the same purpose. Then, the estimated exposure level was compared with the AEL to evaluate the skin sensitization risk. Results:The AEL was calculated as 0.00458 μg/cm 2 based on the EC1.6 value (0.011%, 2.75 μg/cm 2 ) by applying a composite SAF of 600. The estimated TCMSP exposure level from the desk mat was 500 times greater than the AEL, indicating a serious skin sensitization risk.Conclusions: Assessments of skin sensitization potencies of chemicals to be used in consumer products are strongly recommended, and QRAs should be performed at the pre-marketing stage to avoid the skin sensitization risk in consumers.

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