Question

20/27OBLEM: Suppose drinking water contains 1 mg/l of toluene and 0.01 mg/l of tetrachloroethylene (C2C4). A 70 kg adult drinks 2 t/day of this water for 10 years. a) Assess HR and evaluate HR. Was this a safe level of exposure? b) C2C4 is a carcinogen. What would be the carcinogenic risk faced by a person drinking it. Would it be less than 106 (goal)? RfDtoluene 0.2 mg/kg.day RfDc:ci 0.0 mg/kg.day PFc.c 5.1 x 10-2 (mg/kg-day)

Answer 1

Solution A) Given: mg .day RfD of toluene 0.200 kg mg 0.01 day kg RfD of C2Cl4 Body weight, BW = 70kg water intake = 2 L/day mg 1.0 L Concentration of toluene, CToudene mg 0.01 Ccia Concentration of C2Cl4, Chronic Daily intake, CDI for toluene CDIToluene (CToluene* intake)/ BW 1* 2 CDITO luene 2.86 10-2 70

Chronic Daily intake, CDI for C2cl4 CDIC.Cl = (CcCl, * intake)/ BW 0.01 2 CDIC.Ci 2.86 10-4 70 CDI 2.86 10-2 HR for toluene =0.143 RfD 0.200 2.86 10-4 CDI HR for C2Cl4 RfD 0.0286 0.01 Thus from above calculated value of HR for toluene and C2Cl4it is evident that values are less than 1.0 and suggest that no adverse effect on health of subject can occur, thus exposure levels are SAFE.

B) Exposure dose * risk factor * year of exposure Carcinogenic risk = life span of adult Carcinogenic risk, Given, 10-2 risk factor, PF C2Cl4 5.1 0.051 0.2 0.051 10 Cancer riskToluene = 1.45 10-3 70 0.01 0.051 10 Cancer riskcci = 7.28 10-5 70 From above Calculation, it is evident that the carcinogenic risk is less than 10-6 for both tolue ne as well as C2Cl4