# Health risk estimates for iMetHb

## Scope

THIS VARIABLE WILL BE INCLUDED IN THE NITRATE RISK ASSESSMENT IN THE SECOND PASS ASSESSMENT!

To calculate health risk estimates for infant MetHb attributable to nitrate in drinking water.

## Definition

Hazard quotient (HQ)

HQ = Daily nitrate intake / Reference intake

• Reference intake = A level of daily nitrate intake at or below which adverse health effects are unlikely to occur, includes a safety factor
• TDI = Tolerable daily intake (RIVM)
• RfD = Reference dose (U.S.EPA)
• ADI = Acceptable daily intake (U.S.EPA)

Interpretation:

if HQ ≤ 1 → No risk of adverse health effects

if HQ > 1 → There is a risk of adverse health effects

When calculating the Hazard quotient ratio, the exposure level and reference value need to be expressed in the same units, must reflect the same route of exposure, and must represent the same exposure duration.

Margin of safety (MOS)

MOS = NOAEL (or LOAEL) / Daily nitrate intake

• NOAEL = No observed adverse effect level (no safety factors included)
• LOAEL = Lowest observed adverse effect level (no safety factors included)

Interpretation:

If MOSref/MOS ≤ 1 → No risk of adverse non-cancer health effects

If MOSref/MOS > 1 → There is a risk of adverse non-cancer health effects

• MOSref = An overall assessment factor which is derived by combining a number of individual assessment factors.

### Causality

• Acceptable daily intake for NO3
• Environmental risk level for NO3
• LOAEL for NO3
• NOAEL for NO3
• Reference oral dose for NO3
• Total daily ingestion of nitrates in drinking water by infants < 6 months

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### Formula

The variable "Health risk estimates for iMetHb" is found in the Analytica version of the nitrate model. File:Nitrate.ANA

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## Result

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