Safe shampoos, synthetic oil and economics: the latest on cleansers, auto emissions and environmental regulation. (Ask E).

Are the shampoo and bath wash ingredients Sodium Lauryl Sulfate and Sodium Laureth Sulfate hazardous in any way?--Carol Bean, Lyme, NH

Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) are surface cleansers derived from coconut oil, used in a variety of household and industrial products. Anti-SLS/SLES propaganda pervades the Internet and alternative product packaging, but rarely coincides with scientific research.

The Cosmetic, Toiletry and Fragrance Association's Food and Drug Administration-approved experts panel, the Cosmetic Ingredient Review (CIR), has acquitted the slandered sulfates. The CIR reports SLS is "safe in formulations designed for discontinuous, brief use followed by thorough rinsing from the surface of the skin" and SLES, "safe as presently used in cosmetic formulations." According to Tom's of Maine spokesperson Beverly Kardulis, "The claims about SLS are false and unsubstantiated; it's a naturally-derived ingredient, and we're completely comfortable using it in our products."

In substantially higher concentrations, SLS and SLES can cause dermatitis and eye irritation, but no research has suggested any link to other medical disorders. Critics of SLS--usually companies selling alternative shampoos--often mention a study from the Medical College of Georgia (MCG). The study purportedly concludes that SLS inhibits children's eye development, causes cataracts, builds up in critical organs and could lead to baldness. However, according to MCG Regents Professor of Ophthalmology Keith Green, the report's author, "My work does not lead one to those conclusions in any way, shape or form." The actual paper claims only that diluted SLS solution inhibits repair of lesions in a specific corneal membrane. There's not one word about baldness.

For those still concerned about product safety, there are many choices available without SLS and SLES. A quick search on the Internet, or a phone call to most natural product suppliers, will yield numerous alternatives. CONTACT: Health Care Without Harm, [phone], www.noharm.org.

Will using synthetic motor oil, instead of conventional oil, reduce my car's emissions? David Bedell, New Canaan, CT

Conventional oil is derived from petroleum refining; synthetic oils are chemically manufactured replicas. Conventional oils contain impurities that build up, forming deposits in the car. Synthetic oils, by contrast, keep the engine clean and generally free of debris, and can stay on the job three times as long. Unfortunately, synthetics are also three times more expensive.

When your car's engine is badly worn or out of tune, the tailpipe emissions of such noxious byproducts as carbon monoxide, hydrocarbons and particulate matter are greatly increased. Motor oil facilitates the combustion process, but is not involved in the chemistry, and thus its content is not a significant factor in emissions.

Oil is a cause of some emissions when your car is burning oil, of course. Synthetic oils and conventional oils release basically the same pollutants when burned, so there's no advantage in using one over the other. If your car is burning oil, you shouldn't just change the oil to something less polluting; you should take it to a mechanic and get it fixed as soon as possible. Remember there is no way to actually "green" an internal-combustion car. CONTACT: American Petroleum Institute, [phone], www.api.org.

Does environmental regulation negatively impact the economy?--Dustin Calvo, Grants Pass, OR

A classic assumption is that environmental regulations raise prices, put people out of work and cause companies to relocate operations to environmentally careless countries overseas. However, U.S. Census Bureau data found that total 1991 pollution control expenditures--shortly after renewal of the Clean Air and Clean Water Acts--were a fairly insignificant part of raised prices and corporate profit loss. According to the Environmental Protection Agency, the increase would rarely be enough to force plant closings or layoffs.

Although widespread employment insecurity pops up frequently when environmental regulations are a political issue, Department of Labor statistics show that workers are 500 times more likely to be laid off by other factors. A few well-publicized examples, such as the loggers hurt by spotted owl protection in the Pacific Northwest, support the idea of these regulations' negative economic impact on the job market. In The Trade-Off Myth (1999), however, economist Eban Goodstein notes that environmental regulation often increases the number of available jobs. This won't help loggers much, but the economy will remain prosperous. CONTACT: Environmental Defense, [phone], www.edf.org.

Send your questions about environmental issues, from the personal to the political, to Ask E, P.O. Box 5098, Westport, CT 06881, or by e-mail to [e-mail]. Please keep your questions brief and type them double-spaced. Include your full name and address and a daytime phone number.