WHEN A TRUCK overturned near Belmont Center six weeks ago, releasing a potentially explosive ethyl-alcohol-based solution used in hair dye, and forcing the evacuation of 500 residents, it served as a harrowing reminder of a problem that has existed for over 50 years--the inadequate regulation of the cosmetics industry. The hazards posed to public safety by this and other similarly occurring accidents cannot be underestimated. According to a fire chief at the scene, if the chemical-filled cannisters had landed on an incline 50 feet from the accident, they would probably have ended up in the heart of Belmont Center, causing massive civilian casualties.

It is clear that the cosmetics industry is not being adequately monitored when companies are not held responsible for their actions. The company owning the truck at Belmont Center was not made liable for the accident; the driver was charged with nothing more than improperly loading a vehicle. The circumstances of this near-fatal accident indicate clearly that chemicals used in the cosmetics industry are potentially as dangerous as those used in other industries, and therefore transportation regulations of these chemicals should be just as stringent.

But what is even more disturbing than the lack of transportation regulation of these chemicals is the insufficient Federal monitoring of cosmetic products themselves. While the Food and Drug Administration (FDA) can test food and drug products before they are released for general consumption, it can only test those cosmetics which have generated consumer complaints. But since only 343 of an estimated 60,000 cosmetic-related injuries in the U.S. are reported to the FDA annually, the agency seldom has the right to test a product. In the past two years the agency has only tested one kind of cosmetic--hair dye--of the thousands of products on the market.

The result is a vicious circle: while the FDA can only research the effects of cosmetics which it suspects to cause injuries, few injuries are reported because few consumers suspect that damage has been done by cosmetics. Dermatologists report that last year less than half of those suffering from cosmetic-induced skin diseases suspected cosmetics as a cause.

And in the case of many cosmetic products, the damage cannot be treated by a quick trip to the dermatologist. According to government statistics, 500 of 180,000 cases of skin lesions are induced by cosmetics. The chief causes of skin rashes are fragrance preparations, hair and body cream lotions and nail preparations. These lead to skin disorder by seeping through pores and damaging skin tissue. Some cosmetic products have been linked to even more serious health hazards. Improperly prepared mascara, for example, blinded 20 women in 1980.

WHAT WORRY consumer advocates the most, however, are the long-term health effects of seemingly "safe" cosmetics. Cosmetic companies have been known to use chemicals that the National Institute of Office and Safety Regulations listed as dangerous in 1982. Hair dye companies have been known to use nitrosamines--which are a form of banned carcinogens--in their products, while lipstick manufacturers are widely suspected of using carcinogenic substances in their products.

The cosmetic industry's ability to avoid effective regulation is for the most part due to its exceptionally strong lobbying power. This strength was visible last year when the industry's lobby persuaded Congress to defeat a bill calling for the banning of the Braize test, an illegitimate and inhumane method cosmetic companies use to test the toxicity of their products--injecting the product directly into the eyes of laboratory animals. It is safe to assume that this lobby is equally assertive on other questions of 'regulation and, apparently, equally effective. Without public pressure Congress is willing to "let the buyer beware" when it comes to cosmetics.

Short of lobbying Congress for more stringent regulations, consumers can to little to reduce the hazards of the cosmetics industry. It is essential, however, that they exercise caution in buying and using cosmetics. A few basic rules should be to avoid cosmetics containing carcinogens, to avoid ingesting cosmetics (women swallow half the lipstick they wear) and to reduce the chances of infection by avoiding sharing cosmetics. Until the industry itself can be restricted, the consumer must take "caveat emptor" more seriously than ever.