The diaper debate, shrinking beaches and shingle recycling. (Ask E).

Which is better for the environment, disposable or cloth diapers?

--Barbara Fritts, White Lake, MI

The "disposable vs. cloth" debate has raged among environmentalists for 20 years. Non-degradable disposable diapers can sit for decades in landfills and require significant amounts of plastic and pulp. However, the water and chemicals used to clean cloth diapers, and the fossil fuels diaper services consume to transport them, still result in substantial environmental impacts.

Even so, modern advances in water- and energy-efficiency in washing machines and dryers have reduced the environmental damage of diaper laundering. Also, the waste in disposable diapers enters landfills untreated, possibly contaminating groundwater. Whether cloth diaper waste is flushed down the toilet or removed in the washing machine, that dirty water will enter a sewer system and, in most cases, a wastewater treatment plant. Also, a 2001 study published by the National Institutes of Health found trace amounts of dioxins, which are carcinogenic chlorine byproducts, in disposables. Parents can avoid such contamination with organic cotton diapers.

Environmentalists who do want the convenience of disposables can try the cornstarch-based, compostable diapers from Nature Boy and Girl. Using flushable cloth diaper liners by Tiny Tush means only the thinnest--and messiest--part gets thrown away. Parents who want to use cloth diapers can hire a cleaning service to do the dirty work. Check the yellow pages or contact the National Association of Diaper Services (NADS) for a local company. CONTACT: NADS, [phone], www.diapernet.com; Nature Boy and Girl, www.natureboyandgirl.com; Tiny Tush, [phone], www.tiny tush.com.--P.H.

What are people doing about beach erosion?--Jesus Lopez, Santa Maria, CA

From Britain to Galveston, Texas, erosion is causing beaches shrink and coastal bluffs to collapse, while global warming is making everything worse by raising ocean levels. Coastal dwellers are going to great extremes to counter this disappearing act, including often-futile efforts to build costly seawalls.

When Miami Beach bluffs started eroding, the city reinforced them with seawalls. But the erosion continued. Some New Jersey communities built rock walls, called groins, perpendicular to the beach. Groins gather sand, explains Gillian Cambers in his book Coping with Beach Erosion. Another option is a breakwater, a long line of rocks dumped in the ocean parallel to the shore. Japan has built about 6,000 of these to intercept waves, but success is spotty. Restoring beaches by pumping or dredging sand from deep under the ocean is also popular, although it requires repeated applications.

Perhaps a more effective solution is to fix the problem at its source. Dams have impeded the process by which river sediment runs into the ocean and is deposited as beach sand. One solution being considered in Santa Barbara is to remove the problematic dam. According to the Matilija Coalition, two goals could be met if the Matilija Dam on the Ventura River is removed: Santa Barbara beaches would be restored and Ventura River trout could reach the ocean. CONTACT: Matilija Coalition, [phone], www. matilija-coalition.org.--E.H.

Can asphalt roofing shingles be recycled?--Kate Prendergast, Warwick, NY

Asphalt shingles are used by 60 percent of residential homes, according to the National Association of Home Builders (NAHB) Research Center. Each year, re-roofing results in about 11 million tons of waste shingles, and this enormous glut has led to the relatively new option of shingle recycling. The material is ground up, and can then be reused in asphalt pavement, new roofing and fuel oil, according to the California Integrated Waste Management Board.

Recycling the asphalt can, however, lead to a number of potential problems, including difficulty in meeting paving specifications and the possible existence of asbestos, which was used until recently in certain types of shingles. Also, because shingle reuse is rather new, participating recycling centers are few and far between.

Another option is to shred the shingles yourself. Companies such as Astec Industries offer asphalt pulverizing machines; however, these can sell for a whopping $25,000. Just be sure to check your areas safety regulations before working with roofing material. CONTACT: Astec Industries, [phone], www.astecindustries.com; NAHB Research Center, [phone], www.nahbrc.org.--C.L.

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