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July 27, 2011

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Killing pests carefully

SUMMER is pest season and mosquito season and so pesticides, from aerosols to mothballs, are common household weapons. Many people also store cool-weather woolen clothing with mothballs to kill moth larvae and repel insects.

Recent reports about carcinogens in mothballs have frightened many customers and representatives of the pesticide industry recently summoned experts to reassure the public that pesticides are safe if properly used and used to a minimum.

All chemical pesticides are toxic to some degree but following directions for usage should ensure safety. Children, elderly people, pregnant women and people who are weak or have asthma should not be exposed.

Quite a few effective natural pesticides and repellents are available.

Mosquito nets and mosquito blockers with amber lights are effective. Eating raw garlic and food with lots of vitamin B, or taking vitamin B pills, can repel mosquitoes (raw garlic also repels people).

Mosquito-repelling plants include jasmine, evening primrose, azalea, marigold, mint, daphne odera and the well-known chrysanthemums (pyrethrum). The powerful active ingredient in pyrethrum kills and repels insects of all kinds. It is commercially available and easy to use. Many plants are listed online.

At the recent industry-sponsored forum, experts said proper use of certified repellents and insecticides won't harm the body.

In the past, mothballs consisted primarily of naphthalene. It was banned from production in China in 1993 due to carcinogenic properties and flammability.

Today mothballs are made mostly with para-dichlorobenzene. Experts said p-dichlorobenzene is a low-toxicity synthetic that won't cause cancer if used properly. Ordinary daily contact with moth repellents won't damage health, according to Professor Zhou Zhijun, vice president of the Public Health School of Fudan University.

"Though exposure to p-dichlorobenzene of high density can cause problems like dizziness, headache and vomiting, ordinary use of moth-repellent by letting it volatilize naturally in the wardrobe won't harm people due to the limited dose," says Zhou.

Originally moths were repelled with natural camphor wood or oil extracted from the camphor tree. Only white camphor oil is safe and used for therapies, not stronger brown or yellow camphor oil.

In 2008, p-dichlorobenzene was taken off the list of potential carcinogens by the American Consumer Protection Agency, according to Ma Yi, secretary general of the Insecticide Products for Family Health Professional Committee.

Mothballs also may contain prethroid and synthetic camphor.

Prethroid repellent is less toxic than p-dichlorobenzene, but less efficient and more costly.

"Any synthetic chemicals are foreign to the human body, and can be more or less toxic, yet damage can be minimized with careful use of quality products," says Professor Zhou. "The principle is to use only when necessary and to use as little as possible."

The same is true of other pesticides and insect-repellent products such as incense or perfume, experts said.

Natural repellents

? Amber light

Strange but true. Mosquitoes don't like amber light. Turning on an amber light or shining a light through amber-colored cellophane helps repel mosquitoes.

? Mosquito nettingA physical barrier is one of the best methods, and the best for protecting babies since it does not involve chemicals. Avoid nets treated with insecticide. Placing a net over a baby's bed before dark and making sure it's closed can ensure insects don't disturb a child's sleep.

? Repellent plants

Placing a few mosquito-repelling plants in a room helps drive mosquitoes away. They include jasmine, evening primrose, azalea, daphne odera. marigold, mint, citrus (repellent made by boiling rind) and pyrethrum (chrysanthemum family). Pyrethrum powders, sprays and lotions are available.

They kill many kinds ofinsects.

? Foods

Vitamin B and raw garlic give off odors bugs dislike.


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