Risk Assessment and Exposure Equations in Food Safety

Conclusion on Risk Assessment

The final step in risk assessment is to formulate a conclusion on the level of risk posed by a food or ingredient. Previous steps in the assessment process are considered to evaluate the likelihood of the food or ingredient causing harm, based on the nature of the hazard and the level of exposure.

This involves comparing the level of exposure that could potentially cause harm to the actual level of exposure that individuals may encounter in real life. If the actual exposure level exceeds the level known to cause harm, there could be a safety concern, either for the general population or for specific vulnerable groups.

1. Margin of Exposure (MOE)

The Margin of Exposure (MOE) is a risk assessment metric used to prioritize and communicate the risks associated with unavoidable exposure to genotoxic chemical carcinogens. The MOE is calculated by dividing a Point of Departure (POD) from the dose-response curve by the estimated human exposure to the chemical.

    MOE = BMDL10 / Dietary intake

  Example:   If the BMDL10 is 1 mg/kg/day and the dietary intake is 0.02 mg/kg/day, then the MOE is calculated as:

    MOE = 1 / 0.02 = 50

A higher MOE suggests a lower risk, as the exposure level is farther from the point where harmful effects were observed.

2. Hazard Quotient (HQ)

The Hazard Quotient (HQ) is a ratio used to compare the estimated exposure level to a reference dose (RfD). HQ values greater than 1 indicate a potential health risk.

    HQ = Dietary Intake / RfD

  Example:   If the dietary intake is 0.005 mg/kg/day and the RfD is 0.01 mg/kg/day, the HQ is calculated as:

    HQ = 0.005 / 0.01 = 0.5

An HQ less than 1 generally suggests that the exposure is within an acceptable range, while an HQ greater than 1 may indicate a safety concern.

3. Hazard Index (HI)

The Hazard Index (HI) is the sum of hazard quotients (HQs) for multiple chemicals, providing an overall assessment of risk from combined exposures. An HI greater than 1 suggests a potential health risk due to cumulative exposure.

    HI = sum(HQ1 + HQ2 + …)

  Example:   If HQ1 is 0.3, HQ2 is 0.4, and HQ3 is 0.2, then the HI is calculated as:

    HI = 0.3 + 0.4 + 0.2 = 0.9

An HI less than 1 suggests a lower risk from combined exposures, while an HI greater than 1 may indicate an elevated risk.

4. Incremental Lifetime Cancer Risk (ILCR)

The Incremental Lifetime Cancer Risk (ILCR) estimates the probability of an individual developing cancer over a lifetime due to exposure to a carcinogenic agent. It is calculated by multiplying the chronic daily intake by the cancer slope factor (CSF).

    ILCR = Chronic Dietary Intake * CSF

  Example:   If the chronic dietary intake is 0.0001 mg/kg/day and the cancer slope factor (CSF) is 0.05 (mg/kg/day)^-1, the ILCR is calculated as:

    ILCR = 0.0001 * 0.05 = 0.000005

An ILCR value is interpreted as the increased cancer risk over a lifetime associated with the exposure.

5. Target Cancer Risk (TR)

The Target Cancer Risk (TR) estimates the risk of developing cancer based on specific exposure scenarios, calculated using chronic dietary intake and the cancer potency slope (CPs).

    TR = Chronic Dietary Intake * CPs

  Example:   If the chronic dietary intake is 0.0001 mg/kg/day and the cancer potency slope (CPs) is 0.03 (mg/kg/day)^-1, the TR is calculated as:

    TR = 0.0001 * 0.03 = 0.000003

The TR value represents an estimated lifetime risk of developing cancer due to the specific exposure level.