Am. Kadry et al., COMPARISON BETWEEN ORAL AND DERMAL BIOAVAILABILITY OF SOIL-ADSORBED PHENANTHRENE IN FEMALE RATS, Toxicology letters, 78(2), 1995, pp. 153-163
Phenathrene is a major coal tar component found in hazardous waste dis
posal sites. The purpose of this study was to evaluate the extent to w
hich phenanthrene adsorption to either of 2 different soils affects th
e manner in which phenanthrene is subsequently handled in orally and d
ermally exposed adult Female rats. Absorption from the gastrointestina
l tract was relatively rapid for all treatments with maximum plasma co
ncentration of radioactivity occurring within 1 h following oral admin
istration. After dermal application, the time to reach maximum plasma
concentration(12 h) was the same in all 3 phenanthrene treatment group
s although sandy soil lowered the area under the plasma concentration
time curve (AUC) compared to the pure and clay soil groups. Dermal exp
osure increased absorption half-lives 8-fold compared to oral exposure
in the pure group and 15-fold in each of the soil groups. After oral
or dermal treatment with phenanthrene alone or adsorbed to soil, the u
rine represented the primary excretion route of C-14 activity. Ileum c
ontained the highest tissue concentration of radioactivity in all oral
treatment groups. However, the skin application site contained the hi
ghest concentration of radioactivity followed by ileum after dermal ex
posure. Phenanthrenequinone and 9,10-phenanthrene dihydrodiol were the
major urinary metabolites detected in the 0-12-h urine of all treatme
nt groups in both routes of administration. The data suggest that the
oral exposure route for phenanthrene is a greater health risk than the
dermal route. However, the presence of sandy or clay soil tends to de
lay the elimination of phenanthrene from the plasma.