Abstract
When a chemical is detected in a sudden accident or released from a water supply that is not a normal source of contamination, risk management often must be based on limited toxicity information. In such cases, control standards must be set promptly. Therefore, it is necessary to develop a risk assessment system using threshold standards that can comprehensively control a large number of unspecified pollutants to address time constraints and apparent lack of toxicity information. In recent years, due to the inappropriate use of paints used to paint water pipes, the safety assessment of chemicals in paints has attracted attention. Therefore, we tried to construct a scheme to quantitatively and rapidly assess the risk of these substances in a stepwise manner according to the presence or absence of toxicity information and the amount of toxicity information. It is useful for developing a control scheme to use the concept of threshold of toxicological concern (TTC). Although schemes using TTC for food flavourings or leachable substances from food containers are well established, this study examined the applicability of the TTC concept for the safety assessment of substances that may leach from water supply equipment. For genotoxic substances, a threshold to control carcinogens (0.05 μg/L) and a threshold to control non-carcinogens judged to be genotoxic negative (0.5 μg/L) were proposed. These control thresholds were incorporated into a multi-step decision tree based on toxicity information, and a scheme was developed to evaluate chemicals added to paint products used in water equipment.
