Exposure response function for nitrate and iMetHb
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Scope
- European countries
- Infants < 6 months of age
- Oral exposure from drinking water via baby food formula or drinking water.
Definition
Exposure response factor for nitrate exposure from drinking water causing iMetHb.
Causality
Data
Accoding to US EPA IRIS (Integrated Risk Information System) NOAEL for nitrate is 10 mg nitrate-nitrogen/L (1.6 mg/kg/day) and LOAEL is 11-20 mg nitrate-nitrogen/L (1.8-3.2 mg/kg/day). Conversion Factor for nitrate-nitrogen is expressed as the amount of nitrogen within the nitrite molecule commonly shown as mg nitrate-nitrogen/L (1 mg nitrate-nitrogen = 4.4 mg nitrate. The oral Reference Dose (RfD), which is based on the assumption that thresholds exist for certain toxic effects such as cellular necrosis, is 1.6E+0 mg/kg/day. This results in early clinical signs of methemoglobinemia in excess of 10% (0-3 months old infants formula). This results in exposure response factor:
http://www.epa.gov/NCEA/iris/subst/0076.htm
Formula
Unit
Result
If possible, a numerical expression or distribution.