Appendix D Food Codes for NHANES - OEHHA

Scientific Review Panel Draft February, 2012
systemic absorption was estimated at 3.4% of the migrated dose. After skin
washing, the residual fraction in skin at the site of dermal application was 13.8%
of the migrated dose. Assuming the fraction of DEHP in skin will be eventually
absorbed systemically, a maximum absorption rate of 0.24 µg/cm 2 /hr was
calculated.
Barber et al. (1992) carried out an in vitro DEHP dermal exposure study to
compare rates of absorption through full thickness rat skin and human stratum
corneum. DEHP was applied to skin samples in saline solution, and absorption
expressed in terms of absorption rate after 32 hrs of exposure. Absorption
through rat skin and human stratum corneum was 0.42 and 0.10 µg/cm 2 /hr,
respectively, indicating that DEHP more rapidly penetrated rat skin than human
stratum corneum by a factor of 4.2.
Damage to the rat skin observed following exposure was implied as a possible
reason for greater permeability of DEHP through rat skin. Scott et al. (1987) also
compared absorption rates of DEHP through rat and human epidermal
membranes (dermal layer removed), obtaining rates of 2.24 and 1.06 µg/cm 2 /hr
for rat and human skin, respectively. DEHP was applied to the skin sample in
50% v/v aqueous ethanol with exposure up to 53 hrs for rat skin and 72 hrs for
human skin. Damage to rat skin, but not human skin, was also observed by
Scott et al. (1987) after exposure.
B. Supporting Studies
The National Toxicology Program investigated the dermal absorption of 14 Clabeled
DEHP in male F344 rats (Melnick et al., 1987; Elsisi et al., 1989). The
labeled compound was dissolved in ethanol and applied directly to the skin (30
mg DEHP/kg body weight; n = 3 per time point) at a dose of 5-8 mg/cm 2 . The
ethanol was then evaporated and the site of application was covered with a
perforated plastic cap. DEHP showed a very slow rate of excretion over five
days, likely reflecting a slow dermal uptake process. After five days,
approximately 86% of the applied dose was recovered from the skin at the site of
application. However, it was not determined how much of the applied dose
remained on the surface of the skin and how much was absorbed into the skin.
Approximately 5% of the applied dose was recovered in urine and feces, while
the amount of the label remaining in the body five days after dosing was less
than 2% of the applied dose of DEHP.
Ng et al. (1992) examined dermal absorption of DEHP both in vivo and vitro in
hairless guinea pigs. In an in vivo study, radiolabeled DEHP dissolved in
acetone (53 µg DEHP; 34 nmols/cm 2 ) was applied topically on a dorsal area of
the animals which was then covered with a nonocclusive patch. After 24 hours,
the patch was removed and the dosing site cleaned to remove any unabsorbed
compound. Absorption (estimated from urine and feces) was monitored up to 7
days post treatment. To account for incomplete excretion after the compound
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