Determination of no-observed effect level (NOEL)-biomarker equivalents to interpret biomonitoring data for organophosphorus pesticides in children

Table 3 Risk estimates based on the comparison of observed MP and EP excretions with the different proposed NBEs

Scenario	Risk estimate^a				No. of risk estimates >1
Metabolites considered	mean	SD	median	max
1- Comparison with the oral NBE derived from scenario 1 ^b
Methylphosphates	0.04	0.06	0.02	0.71	0
Ethylphosphates	0.01	0.01	0.01	0.08	0
Sum of methyl+ethylphosphates	0.05	0.07	0.03	0.74	0
2- Comparison with the oral NBE derived from scenario 2 ^c
Methylphosphates	0.04	0.05	0.02	0.59	0
Ethylphosphates	0.01	0.01	0.01	0.14	0
Sum of methyl+ethylphosphates	0.04	0.06	0.02	0.63	0
3- Comparison with the dermal NBE ^d
Methylphosphates	0.11	0.17	0.05	1.88	1
Ethylphosphates	0.02	0.03	0.01	0.23	0
Sum of methyl+ethylphosphates	0.12	0.17	0.06	1.92	1

^a The risk estimate corresponds to the ratio observed metabolite excretion/NBE.
^b Simulation of an oral exposure to the NOEL of either malathion or chlorpyrifos at 6:00 pm.
^c Simulation of an oral exposure to 1/3 of the NOEL of either malathion or chlorpyrifos at 7:00 am, noon and 6:00 pm.
^d Simulation of an 8-h dermal exposure to the NOEL of either malathion or chlorpyrifos starting 12 h prior to the onset of urine sampling.

ISSN: 1476-069X