Effects of skin preapplication treatments and postapplication cleansing agents on dermal absorption of 2,4-dichlorophenoxyacetic acid dimethylamine by Fischer 344 rats.
Various methods of preparing dermal application sites in Fischer 344 rats prior to exposure to 2,4-dichlorophenoxyacetic acid dimethylamine salt (2,4-D amine) and the effect of various cleansing agents following exposure were examined by measuring recoveries of 14C-labeled 2,4-D amine in skin, postapplication cleansing solution, blood, and urine. The middorsal area of the rat was the site of application for four treatments tested: (1) hair clipping only, (2) hair clipping followed by an epilatory cream, (3) hair clipping plus shaving with an electrical razor, and (4) as in treatment 3 followed by washing with soap and water. A last preparation was the rat's tail thoroughly brushed with soap and water. The results indicated that the tail retained greater than 75% of the material, thus preventing its absorption into the blood stream and subsequent removal by cleansing. With treatment 1 the dense short hair remaining after clipping impaired the absorption of 2,4-D as evidenced by considerably lower blood and urinary levels than treatments 2-4. With preparations 1-4, 45-61% of the dose was removed with the 7-h postapplication cleansing and a further 5-6% with the subsequent 23-h cleansing. In other studies using preparation 3 above, the following cleansing agents were tested: soap and water, water, isopropanol, acetone, and Rad-Con, a foam-producing cleanser. Rad-Con removed more 2,4-D from the skin than other cleansing agents after 7 h of exposure and more than soap and water after 23 h. The percentages of 2,4-D left on the skin following either 7- or 23-h cleansing with Rad-Con were 8-12%, nearly half those following the other cleansing agents. Cleansing agents other than Rad-Con presented little advantage over soap and water. With all cleansing agents, delaying cleansing from 7 to 23 h after exposure resulted in higher blood and urinary levels of 2,4-D measured 24 h after application.
Pelletier
O
O
Pesticides Division, Environmental Health Centre, Health Protection Branch, Ottawa, Ontario, Canada.
Ritter
L
L
Caron
J
J
D000433:1-Propanol; D015084:2,4-Dichlorophenoxyacetic Acid / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D000096:Acetone; D000287:Administration, Topical; D000818:Animals; D003666:Decontamination; D003902:Detergents; D004123:Dimethylamines / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D006204:Hair Removal / Q000379:methods*; D006540:Herbicides / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D051381:Rats; D011916:Rats, Inbred F344; D012869:Skin Absorption; D012915:Soaps; D014867:Water
D003902:Detergents; D004123:Dimethylamines; D006540:Herbicides; D012915:Soaps; D014867:Water; D000096:Acetone; C037991:2,4-D amine; D015084:2,4-Dichlorophenoxyacetic Acid; D000433:1-Propanol