Question 1

How is estimated daily intake (EDI) calculated?

Accepted Answer

EDI = (C x IR) / BW, where C is the contaminant concentration in the food item (mg/kg), IR the daily ingestion rate (kg/day) and BW the body weight (kg). The result is mg per kg body weight per day.

Question 2

How do you calculate the target hazard quotient (THQ)?

Accepted Answer

THQ = EDI / RfD, dividing the estimated daily intake by the oral reference dose for that element. THQ below 1 indicates no appreciable non-carcinogenic risk; THQ of 1 or above indicates potential concern.

Question 3

What is the hazard index (HI)?

Accepted Answer

HI is the sum of the individual THQ values across all contaminants for the same exposure route: HI = sum(THQ). HI above 1 signals possible cumulative non-carcinogenic risk even when every single THQ is below 1.

Question 4

How is carcinogenic (target) risk calculated?

Accepted Answer

TR = EDI x CSF, using the oral cancer slope factor. Values between 1e-6 and 1e-4 are usually treated as acceptable, and above 1e-4 as unacceptable lifetime risk.

Metal	Conc. (mg/kg)	RfD (mg/kg/d)	CSF (mg/kg/d)⁻¹

Risk Assessment

1Metal Concentrations & Reference Doses