NEHA November 2022 Journal of Environmental Health

November 2022 • Journal of Environmental Health 41 three steps of scientific evaluations as described earlier. The chemical database provides a summary of the critical toxicity studies used to derive health guidelines and suggests which toxicity values health assessors should use for making decisions about possible health e ects. PHAST was initially launched in 2017 and has since undergone continuous enhancements. In addition, several auxiliary tools have been developed to further complement this application and enhance its versatility and functionality, including an Exposure Point Concentration (EPC) Tool and a Shower and Household Water-Use Exposure (SHOWER) Model (Figure 2). Exposure Point Concentration Tool The EPC Tool is a web-based application built to assist health assessors with estimating EPCs for discrete environmental data, which can then be used in PHAST to calculate exposure doses, hazard quotients, and cancer risk. Discrete data are obtained from individual environmental samples from a given point and time that is independent of other samples. Estimating a reasonable EPC is important as it represents the contaminant concentration at a specific location(s) where people might come into contact with a contaminated medium. For each environmental data set imported into the tool, the program calculates an EPC that is either the 95th percentile upper confidence limit of the mean of the data or the maximum value of the data for cases where 95th percentile upper confidence limits cannot be reliably calculated. The EPC Tool automates a series of procedures and calculations so that health assessors can quickly and accurately calculate EPCs for their data in an easy-to-use program in accordance with chemical and mediaspecific scientific procedures and guidance (ATSDR, 2022). The tool also provides useful supporting tables and figures with summary statistics and other information about the calculated EPCs (e.g., boxplots, other descriptive statistics). Finally, it allows health assessors to export the calculated EPCs and other data (e.g., maximum values for screening) for additional analysis in PHAST. Evaluating Exposures From Household Use of Water PHAST is capable of evaluating residential inhalation and dermal exposure from bathing and showering in contaminated water and from other household water use, such as washing machines and dishwashers. Using results imported from the ATSDR standalone desktop SHOWER model, PHAST can generate hazard quotients and cancer risk estimates for up to eight persons, taking into consideration all household water uses. The SHOWER model can simulate either inhalation and/or dermal exposure for 830 volatile and semivolatile chemicals. The Home Page of the Public Health Assessment Site Tool Conceptual Diagram of the Public Health Assessment Site Tool, Related Applications, and Types of Input and Output Data Note. EPC = Exposure Point Concentration; SHOWER = Shower and Household Water-Use Exposure. FIGURE 1 FIGURE 2