Pesticide residues in food — 2006: Toxicological ... - ipcs inchem

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Figure 4.Transfer of radioactivity through rat and human epidermal membranes after a
singlapplication of [ 14 C]boscalid at a nominal dose of 1000 μg/cm 2 (100 mg/ml)
25.0
μg equivalents boscalid absorbed/cm 2
20.0
15.0
10.0
5.0
Rat
Human
0.0
0
3 6 9 12 15 18 21 24
Exposure time (h)
From Thornley & Bryson (2001)
The differences in the skin penetration between human and rat skin at the different doses
(based on the rates of penetration) are shown in Table 7. Based on comparison of penetration rates
or p ermeability coefficients, it appears that penetration rate through rat epidermis is at least a
7.7-fold that through human epidermis. The recovery of radiolabel was determined at the end of the
e xperiment and summarized in Table 8 (Thornley & Bryson, 2001).
Table 7. Difference in penetration of boscalid through rat and human skin
Species Mean rate of penetration (μg/cm 2 per h)
Dose administered (μg/cm 2 )
10 100 1000
Rat epidermis 0.302 0.685 3.813
Human epidermis 0.015 0.050 0.498
Fold difference 20.1 13.7 7.7
From Thornley & Bryson (2001)
Table 8. Study of dermal penetration in vitro: recovery of radioactivity through rat and human skin
Parameter
0.01 mg/cm²
(1 mg/ml)
Recovery of 14 C radiolabel (% of applied dose) at 24 h
Dose applied
0.1 mg/cm²
(10 mg/ml)
1.00 mg/cm²
(100 mg/ml)
Rat Human Ratio Rat Human Ratio Rat Human Ratio
Receptor fluid 32.54 4.545 7.2 3.954 1.416 2.8 3.482 0.641 5.4
Receptor cell wash 1.809 0.485 3.7 0.368 2.596 0.1 1.150 0.509 2.3
Total penetrated 34.35 5.03 6.8 4.322 4.012 1.1 4.632 1.15 4.0
BOSCALID X-X JMPR 2006