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Dichlorvos (DDVP) Risk Characterization Document - California ...

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APPENDIX D<br />

CALCULATION EQUATIONS<br />

1. Dosage estimation for animals from an inhalation study (exposure level in ppm):<br />

mg/kgdaymg/m 3 ×respiration rate(m 3 hours exposed days exposed/week<br />

/kgday)× × ×AF<br />

24 hours<br />

7 days<br />

For this equation, 1 ug/L in air is equivalent to 1 mg/m 3 . The term for number of days exposed per<br />

week/7 days is used in the calculation only for studies when the animals were not dosed every day.<br />

The dosage was not corrected for absorption (absorption factor, AF). Only the dosages used in the<br />

calculation of MOS are corrected for 50% inhalation absorption rate.<br />

The default respiration rates used are: 0.46 m 3 /kg-day for children, 0.26 m 3 /kg-day for human adults,<br />

0.96 m 3 /kg-day for rats, 0.54 m 3 /kg-day for rabbits, and 1.80 m 3 /kg-day for mice (Zielhuis and van der<br />

Kreek, 1979).<br />

For example:<br />

Using the NOEL of 1.25 ug/L from Thorpe et al. (1971b) where rabbits were exposed<br />

to <strong>DDVP</strong> daily,<br />

1.25 mg<br />

× 0.54 m 3<br />

m 3 kgday<br />

×<br />

23 hours<br />

24 hours<br />

0.65 mg/kgday<br />

2. Dosage estimation for animals in a dietary study (exposure level expressed as ppm in the diet):<br />

ug/kgday ppm (ug/g) xFR(g/day) x<br />

1<br />

body weight (kg)<br />

x<br />

days exposed/week<br />

7days<br />

The food consumption rate (FR) is derived either from the reports or the standard default is used. The<br />

standard default is based on body weight, 15% for mouse, 5% for rat, and 3% for rabbit.

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