Printer Friendly

Hairy portals for toxic chemicals.

Hairy portals for toxic chemicals

Toxicologists tend to focus on the nose and mouth as passageways through which hazardous chemicals enter the body. Skin is another portal for these chemicals, but its role is far less understood. Conventional wisdom has held that the skin's outermost layer of dead cells served as a passive barrier, and that simple diffusion set the rate at which chemicals passed through this inert filter. But that didn't explain why skin permeability at different parts of the body can vary dramatically. A study performed at Oak Ridge (Tenn.) National Laboratory now reveals that structural factors in skin--like hairiness--can affect absorption.

Skin does not present a uniform barrier. Among the "holes" penetrating it are hair follicles, sebaceous glands and sweat glands. John Kao (now at Smith Kline and French Laboratories in King of Prussia, Pa.) and his co-workers at Oak Ridge decided to examine the role of such holes by measuring the penetration of two chemicals -- the male hormone testosterone and the pollutant benzo[a]pyrene (BP), a suspected human carcinogen -- in skin cultured from hairy and hairless strains of mice.

Their findings, reported in the June 15 TOXICOLOGY AND APPLIED. PHARMACOLOGY, show that 4.4 to 9.4 percent of the BP penetrated the skin from hairy mice--two to three times more than was absorbed through the hairless-mouse skin. Testosterone, however, penetrated both types of mouse skin equally -- about 12 to 16 times more readily than BP passed through hairy-mouse skin.

The reason for the chemical differential, explains Jerry Hall, one of the study's authors, is metabolism. The researchers had previously found that healthy skin, far from being inert, can conduct "extensive" metabolism -- or biological alteration -- of chemicals. And this can affect a chemical's skin-penetrating ability.

As fat-seeking chemicals, both BP and testosterone will preferentially deposit at the hair follicles and sebaceous glands, focal sites of metabolic activity. BP must be altered by an enzyme in order to penetrate. Testosterone, however, can pass through directly. It now appears, Hall says, that hair follicles and glands can play a major role in chemical absorption through the skin, especially with those fat-seeking chemicals like BP that require metabolic alteration for penetration.
COPYRIGHT 1988 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1988, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:research on chemical absorption through the skin
Author:Raloff, Janet
Publication:Science News
Date:Jun 25, 1988
Previous Article:Neuron selectivity: down memory lane.
Next Article:Birth-control vaccine safe in early tests.

Related Articles
Unwanted formaldehyde 'breakthrough'.
Five-fold increase in Superfund money.
Toxic shock and tampons revisited.
Dioxin via skin: a hazard at low doses?
Greenery filters out indoor air pollution.
Foundries face stricter air quality, pollution monitoring.
Deadly beauty, nontoxic news and corporate conscience. (Ask E).
Low-temperature HNBR technology.
The truth in beauty.
Lung response to inhaled highly toxic chemicals.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters