Week of 6/5/05

Dear EarthTalk: What are the health and environmental consequences of some of the methods used to control mosquitoes, ticks and other insects?

—Hunter White, Lafayette, IN

By far the most popular form of insect repellent available to consumers in the U.S. is diethyl-meta-toluamide, known popularly as "DEET." According to the U.S. Environmental Protection Agency (EPA), each year approximately one-third of the U.S. population uses insect repellents containing DEET, which is the active ingredient in more than 230 products, including sprays, lotions, liquids and wristbands.

But recent laboratory animal studies have found that frequent and prolonged exposure to DEET can cause neurons to die in regions of the brain that control muscle movement, learning, memory and concentration. Other studies using humans have found adverse effects ranging from skin irritation and blisters to memory loss, even seizures. Very high exposures, such as those that occur if the repellent is swallowed, have caused neurological damage in at least 18 children, three of whom died as a result. Yet despite these threats, the EPA insists that DEET products are safe as long as consumers follow the directions carefully.

Meanwhile, bug zappers—which emit ultraviolet light to draw pests—kill few if any mosquitoes, which are attracted not to light but to our body heat and the carbon dioxide we exhale. Some four million zappers are at work in the U.S., toasting nearly 71 billion insects—mostly non-target bugs—each month. The most common bugs killed are beetles, moths, flies, bees, ants and wasps, many that are themselves beneficial for insect control as well as pollination.

But while there are issues with many localized forms of pest control, most troublesome are the potential public health effects of the widespread application of "organophosphate" pesticides, such as Malathion, intended to wipe out large mosquito populations for miles around. In recent years, cities and states looking to stave off mosquito-borne maladies like West Nile Virus have undertaken large-scale mosquito control projects—often involving the use of Malathion. According to Pesticide Action Network, Malathion is chemically related to the nerve gases used in World War II. It kills by disrupting nervous system processes, and has been linked to cancer, nervous system disorders and a wide range of other maladies in humans.

One environmentally friendly alternative mosquito control method is Bacillus thuringiensis israelensis (BTI), a bacterium that can be applied to mosquito breeding grounds, usually in places where standing water collects. BTI is a naturally occurring organism that targets only the larvae of insects, and as a result poses no health threat to humans or wildlife. Some hardware stores stock BTI-infused mosquito "dunks" which are activated when wet. Another somewhat more costly option is the Mosquito Magnet, a trap that attracts mosquitoes by emitting an irresistible combination of carbon dioxide, heat and moisture. But perhaps the safest way to avoid bug bites is to don the always-dapper combination of a long-sleeved shirt, long pants, ankle socks and a wide-brimmed hat.

CONTACTS: U.S. EPA DEET Page, www.epa.gov/pesticides/factsheets/chemicals/deet.htm ; Pesticide Action Network, (415) 981-1771, www.panna.org ; Arbico Organics" Mosquito Control with BTI, http://store.arbico-organics.com/organic-pest-control-most-requested-mosquito-control.html.


Dear EarthTalk: What exactly are PZEV cars? Someone told me they were very clean, and on the market now.

—Thomas Lyons, Jamaica Plain, MA

Thanks to rigorous auto emissions standards in California—where regulators are trying to clean up the worst air in the country—no less than a dozen car companies now offer Partial Zero Emission Vehicle (PZEV) cars for sale in the U.S. While these cars run on gasoline and don’t necessarily get better mileage than their traditional counterparts, they do produce much cleaner emissions by controlling exhaust gases with sophisticated engine controls and advanced catalytic converters.

Most auto pollution is released while a car is warming up and the catalytic converter is still cold. But PZEVs, through the use of lightweight steel and aluminum components, computerized valve timing and other advanced engineering technologies, heat the catalytic converter quickly, which reduces emissions significantly. These reduced emissions qualify the cars as "low-emission vehicles" (LEVs) in the "clean car states" of California, New York, Massachusetts, Vermont and Maine, each which requires automakers to sell a certain percentage of "green" cars.

Environmentalists are optimistic that the fast-growing fleet of PZEVs on America"s roads will have a much larger and more positive impact on environmental quality than the even cleaner running gasoline-electric hybrids, which are still niche vehicles. In fact, already for every hybrid Prius sold by Toyota since it was introduced in 2000, Ford has sold three PZEV Focuses.

Indeed, what"s perhaps most striking about the push by automakers to produce PZEVs is the lack of hype surrounding the vehicles, especially in light of all the attention being paid to the hybrids and to the coming hydrogen fuel cell cars. All new versions of Ford"s popular Focus model, for example, meet PZEV standards, but consumers wouldn’t know it unless they were to ask. Compared to a similar size traditional car, the PZEV Focus produces 97 percent fewer hydrocarbon and nitrogen oxide emissions, and 76 percent less carbon monoxide.

According to California"s DriveClean website, car buyers looking to jump on the PZEV bandwagon will have to shell out a few hundred dollars extra for the greener technology, but have several models to choose from, including BMW"s 325i, Dodge"s Stratus and Sebring, Honda"s Accord, Hyundai"s Elantra, Mitsubishi"s Galant, Nissan"s Sentra, Subaru"s Legacy, Toyota"s Camry, Volkswagen"s Jetta, Volvo"s S60 sedan and V70 wagon, and of course, Ford"s Focus. Consumers in the five "clean car states" should be able to order any of the PZEV models at local auto dealers. Only the Ford Focus is readily available in all 50 states but, according to the magazine Green Car Journal, "it"s just a matter of time until the rest of the country catches up and we can all breathe a bit easier."

CONTACT: Ford Focus, www.fordvehicles.com/cars/focus ; California"s DriveClean Website, www.driveclean.ca.gov ; Green Car Journal, www.greencar.com .