Any Alternatives To DEET To Keep Mosquitoes Away?

Dear EarthTalk: Is it true that the DEET used in most mosquito repellents is toxic? If so what problems does it cause? And what are some non-toxic alternatives for keeping mosquitoes at bay?

—Tom Porter, Oakland, CA


DEET is commonly known as the king of mosquito repellents, though not everyone is keen to slather it on their skin. A study conducted in the late 1980s on Everglades National Park employees to determine the effects of DEET found that a full one-quarter of the subjects studied experienced negative health effects that they blamed on exposure to the chemical. Effects included rashes, skin irritation, numb or burning lips, nausea, headaches, dizziness and difficulty concentrating.

Duke University pharmacologist Mohamed Abou-Donia, in studies on rats, found that frequent and prolonged DEET exposure led to diffuse brain cell death and behavioral changes, and concluded that humans should stay away from products containing it. But other studies have shown that while a few people have sensitivity to DEET applications, most are unaffected when they use DEET products on a sporadic basis according to the instructions on the label.

The upside of DEET is that it is very effective. A 2002 study published in the New England Journal of Medicine found that DEET-based repellents provided the most complete and longest lasting protection against mosquitoes. Researchers found that a formulation containing 23.8 percent DEET completely protected study participants for upwards of 300 minutes, while a soybean-oil-based product only worked for 95 minutes. The effectiveness of several other botanical-based repellents lasted less than 20 minutes.

But a number of new concentrations of botanical repellents that have hit the market since are reportedly better than ever. In 2005, the U.S. Centers for Disease Control (CDC) granted approval to two healthier alternatives to DEET—picaridin and oil of lemon eucalyptus—for protection from mosquitoes. Picaridin, long used to repel mosquitoes in other parts of the world, is now available in the U.S. under the Cutter Advanced brand name. Oil of lemon eucalyptus, which is derived from eucalyptus leaves and is the only plant-based active ingredient for insect repellents approved by the CDC, is available in several different forms, including Repel Lemon Eucalyptus, OFF! Botanicals, and Fight Bite Plant-Based Insect Repellent.

Some other good choices, according to the nonprofit National Coalition against the Misuse of Pesticides, include products containing geraniol (MosquitoGuard or Bite Stop), citronella (Natrapel), herbal extracts (Beat It Bug Buster) or essential oils (All Terrain). The group also gives high marks to oil of lemon eucalyptus, such as that found in Repel’s Lemon Eucalyptus Insect Repellent.

Another leading nonprofit, Pesticide Action Network North America (PANNA), likes Herbal Armor, Buzz Away and Green Ban, each containing citronella and peppermint as well as various essential oils (cedar wood, lemongrass, etc.). PANNA also lauds Bite Blocker, a blend of soybeans and coconut oils that provides four to eight hours of protection and, unlike many other brands, is safe to use on kids.

CONTACTS: “Comparative Efficacy of Insect Repellents against Mosquito Bites”; National Coalition Against the Misuse of Pesticides (NCAMP); Pesticide Action Network North America

Dear EarthTalk: I want to offer my employees a 401(k) plan that is socially and environmentally responsible. Are there such plans and, if so, where do I look?

—CJ Hughes, Queens, NY

Responding largely to employee demand, more and more companies are now offering greener options for 401(k) retirement investment accounts.© Getty Images

Even though socially responsible investing (SRI) has been around for decades, only recently have some companies begun to offer their employees greener options for 401(k) retirement investment accounts.

According to Rona Fried of, SRI options for retirement plans are still only offered to about 20 percent of employees, but that’s changing fast. One survey found that more than two-thirds of employees want such choices. And a 2007 survey by the Social Investment Forum found that 60 percent of benefit plan sponsors polled plan to include SRI options for retirement funds by 2010.

Retirement accounts are big business in the U.S.: Some 50 million Americans have invested $2.5 trillion in 401(k) plans to date. With so few SRI options out there now and employees eager to make their savings work for the environment, greener 401(k) plans are sure to take a bigger and bigger slice of the pie moving forward. “It’s a matter of simple supply and demand,” says Paul Hilton of Calvert Funds, which currently offers one SRI retirement fund option but plans to add two more within the next couple of years. “Corporations are responding to the increasing desire of Americans to invest with their values.”

Right now health care and government agencies are those most likely to include an SRI option for employees” retirement accounts, but a handful of large companies have gotten in on the act as well. For instance, chipmaker Intel began offering its employees an SRI retirement plan option eight years ago.

“In 2000, we were trying to create a culture of corporate social responsibility and it made sense for us to practice what we preach by including this option in our retirement plan,” says Dave Stangis, Intel’s director of corporate responsibility. “In addition, Intel itself is a top holding in many SRI mutual funds and we wanted to reinforce that with our employees. It’s a way for us to be a role model.”

Still, most plans give employees only a limited number of funds to choose from, often from Calvert and another SRI mutual fund leader, Domini. Both firms ply the three main tenets of SRI: (1) rigorous research to assess the social and environmental integrity of companies being considered for inclusion in an investment portfolio; (2) using investors” positions as stockholders (i.e. owners) of companies invested in to advocate for good corporate citizenship (often through the introduction of corporate resolutions); and (3) channeling affordable credit to needy communities ill-served by traditional lenders to rebuild neighborhoods and create jobs. SRI funds are also increasingly making “early stage” investments in new companies on the cutting edge of environmental progress, such as alternative energy companies.

In order to help diversify the marketplace for SRI retirement plans, consultant Rob Thomas started Social(k) in 2005 to offer companies a full array of SRI options for their 401(k) plans. Social(k) offers 140 different SRI funds from which employees at participating companies can choose. Thomas’s goal is to offer as many funds as possible and become the one-stop shop for retirement investing. Companies can offer either Social(k) alone, or as a secondary option alongside an existing 401(k) plan.

CONTACTS:; Calvert Funds; Domini Social Investments; Social(k)