Abstract
Sources of water supply can be influenced by chemical accidents, and the concentration of contaminants may transiently exceed the level of the guidance values (GVs) such as Drinking Water Quality Standards (DWQS) or non-legally binding target values. In such cases, the subacute guidance values (SGVs), i.e. concentrations of drinking-water contaminants that will not affect human health for subacute exposure duration, will be useful for risk management. We previously proposed SGVs of 43 organic items that can be contaminated in drinking-water, and most SVGs were calculated to be 4 to >10 times higher than the corresponding GVs. In this study, we attempted to derive SGVs for 6 inorganic metals additionally. The NOAEL or BMDL10 of a subacute study was basically used with a total uncertainty factor of 100 to establish Subacute Reference Dose (saRfD). SGVs were calculated by using the saRfDs and allocation factor of 100%. SGVs of cadmium and selenium whose GVs were derived by human epidemiological studies were also calculated as 3-4 times higher than GVs. On the other hand, SGVs for a few items such as arsenic and chromium (VI) were no alternative but to be evaluated as same as GVs. For these contaminants, immediate action will be required. Taken together, the SGVs we proposed in this and previous studies are considered useful for risk management of the contaminants in drinking-water. ACKNOWLEGMENT: This study was supported by a Health and Labour Sciences Research Grant (19LA1005) from the Ministry of Health, Labour and Welfare, Japan.
