Water from a rural residential well contains 15 ppb of arsen

Water from a rural residential well contains 15 ppb of arsenic and 10 ppb of cadmium.A 70-kg adult drinks 2 L/day of this water for 10 years. Calculate the hazard index (chronicnoncarcinogenic effects) for this water. Would HI suggest that this was a safe level of exposure?

Solution

LE= Life expectancy. The number of year that the person is likely to live. Not used for non-carcinogens.

Concentration of arsenic and cadmium

Arsenic = 15ppb = 0.015 ppm or mg/kg

Cadmium = 10 ppb = 0.01 ppm or mg/ kg

Since the adult is drinking 2L/day, the concentration therefore, it will be 0.03 ppm of arsenic and 0.02 ppmof cadmium.

Dose (water ingestion) = C_W × IR_W × AF_GIT × DDays × DWeeks × DYears)/ BW × 365 × LE

Hazard quotient = dose rate / reference dose

LE assumed to be 100 unless given

Dose (water ingestion) = C_W × IR_W × AF_GIT × DDays × DWeeks × DYears)/ BW × 365 × LE

Dose (water ingestion) = 0.03 × 2 × 1 × 7 × 52 × 10)/ 70 × 365 × 100 (arsenic)

= 0.00008548

Dose (water ingestion) = 0.02 × 2 × 1 × 7 × 52 × 10)/ 70 × 365 × 100 (cadmium)

= 0.00005699

This value can be used to calculate the hazard quotient as for A Hazard Index (HI) is the sum of HQ’s for all pathways and similar toxic effects will be required.