Taking a Look at the Skin We’re In : THE BODY’S EDGE: Our Cultural Obsession With Skin by Marc Lappe; Holt $22.50, 242 pages

The French, of course, have a phrase for it: Mal dans sa peau. To be, literally, bad in one’s skin, a phrase that attributes more psychological and physiological importance to that organ than most of us care to acknowledge. It’s bad enough when the obsession lacks depth, as in a silly superficial preoccupation with, say, beauty or aging (no one you or I know spends any time thinking about these things). Marc Lappe adds health and spiritual vigor to the reasons why we ought to care for our hides and live well in them.

Rest assured that no matter how rich pathologist and author Lappe’s explanation of our cultural obsession with skin, you will not be cured. If you are someone who spends roughly half the GNP of the Dominican Republic per year on skin care products, his insights into perceptions of beauty in other cultures will not change your behavior. If you were hoping for a scientist to tell you that unlimited sunbathing is now considered OK by the medical establishment, Lappe’s musings on more ancient forms of self-mutilation among American Indians do not constitute a green light for sun worshipers. Elizabeth Arden did not underwrite this book.

But “The Body’s Edge,” bigger than a Vogue article and smaller than the “Merck Manual” or “Gray’s Anatomy,” is more than the meanderings of a well-known scientist. Lappe’s central theme is that “healthy skin may be critical for our more general well-being.” It is “our boundary line between inner wellness and external danger, between psychic openness and closed armoring.” He hypothesizes that “over evolution the sensoria that reside in skin have been blunted as higher centers that coordinated visual and auditory cues became more important to survival. Those cutaneous sensory systems that once enabled us to experience a rich and varied world of texture, pressure, heat and vibration have been dampened and replaced by this more central system.”

Not much is provided here as a guideline for increasing our skin’s sensitivity, hence increased texture and meaning in our lives, but there is a very concise and up-to-the-minute explanation of how healthy skin functions and a good explanation of how we ought, given the most recent research available, to think about our skin; in other words, how to update our obsession.

First of all, we can no longer think of skin as a two-dimensional, impermeable barrier. Lappe (whose other books include “Chemical Deception” and “Evolutionary Medicine”) provides several examples of chemical poisoning in which the skin was “the portal of entry.” He explains the skin as a complex organ, a “highly convoluted, vulnerable, three-dimensional landscape” that may even possess its own immune response system. This system, Lappe explains, is assisted by skin cells called keratinocytes and others, perhaps more importantly, called Langerhans cells, which originate in the bone marrow and migrate to the skin’s surface where they quite literally create a net through which antigens must pass.

If we acknowledge the skin as our first line of defense against disease, it behooves us to strengthen the skin’s chemical detoxification apparatus, as well as the enzyme systems that “permit repair of the DNA damage from ultraviolet light,” Lappe writes. Again, the book is not generous with ideas for how the reader can accomplish this in the privacy of his own home, save staying out of the sun, taking vitamin E and perhaps using Retin-A, recently approved by the FDA, which stimulates the basal skin layer, thickening the epidermis and hiding wrinkles.

Again, this kind of information is more likely to show up in the Vogue article than in “The Body’s Edge.” But for the really strange, the chapter on “Diseases of the Skin” (with more Merck-like nerd appeal) is fascinating--if you can admit to a somewhat unhealthy interest in trench foot, scabies and vitiligo. After all, they’re only skin-deep.