Are lice treatments safe?
Products that kill lice and scabies aren't 'shampoos.' They are insecticides.
Mon, Mar 09, 2009 at 10:36 AM
Q: My child has head lice! I have gotten conflicting information on treatment. Are the over-the-counter medications safe to use? What other options do I have?
I’m always a bit pedantic when it comes to environmental subjects, but it’s nice to have a literal excuse to be nitpicky! So, thank you for the question.
Head lice — those tiny, wingless parasitic insects that live on the human scalp and glue their eggs to our hair — are practically inescapable. They can’t fly, hop or jump, but they certainly can get around.
It is safe to expect that you (or more probably, your child) will get lice at least once. While social stigma and fallacious notions of hygiene attached to lice have somehow survived, the louse hath no prejudice. Long or short, curly or straight, clean or dirty, our hair and scalps provide the perfect environment for lice: just the right temperature, protection and moisture levels. Add the miniscule bit of blood they draw from us several times a day, and you’ve got a haven for Pediculus humanus capitis. Only the human head will do: they do not live anywhere else on the human body, or on animals, and can only survive about two days without feeding on human blood.
Lice may be a nuisance, but they are not a public health menace. Head lice aren’t dangerous and don’t spread disease. At worse, persistent scratching can cause the skin to become irritated or infected.
So what to do about these annoying, harmless, persistent creatures? Bathe our children in pesticides and nerve gas, of course!
Understand your toxins
Lindane, a neurotoxin, is commonly used as a pesticide. Known to cause cancer and harm the human nervous, reproductive and hormonal systems, lindane is one of the ingredients of choice in lice treatment products. The U.S. has banned lindane for some uses, and many countries have abandoned it altogether, but we continue to use it to kill lice. Of course, lice are usually found on children, whose developing bodies are particularly vulnerable to toxic threats. In the U.S., use of lindane on animals has been banned, but you can buy it for the human members of your family. Treatment with lindane can result in vomiting, seizures, brain damage, spontaneous abortion, learning problems, epilepsy and death. The pesticide is categorized by the U.S. Environmental Protection Agency (EPA) as a persistent, bioaccumulative and toxic pollutant — meaning it lingers for a long time in the environment, accumulates as it moves up the food chain, and is highly toxic to humans and wildlife. As the allowable limit for lindane in drinking water sources is 19 parts per trillion, a single treatment of lindane to kill head lice or scabies pollutes 6 million gallons of water.
Malathion, a nerve gas derivative often used for insect control, is considered safer than lindane. Malathion is an organophosphate and kills by interfering with the nervous system. It is considered an “unclassifiable carcinogen,” neurotoxin, asthma trigger and suspected endocrine disruptor (meaning it affects normal hormone activity). Human exposure can cause nausea, dizziness, confusion, respiratory paralysis, and death. Although it is known to be readily absorbed by the skin, manufacturers have yet to measure how much malathion is absorbed from lice-killing applications. Nor have they bothered to find out if it is excreted in human milk, or even if it is safe or effective for children under six years of age. Have they studied its potential to impair fertility, cause cancer, and “muta-genesis”? No. Oh, and it is flammable, so the manufacturers warn people to stay away from flames, dryers, hair curlers, cigarettes, heaters…
Pyrethroids (permethrin, pyrethrin, et al) are synthetic pesticides that can cause pneumonia, muscle paralysis, death due to respiratory failure, vomiting, and asthma, and are toxic to the thyroid and immune system. No safe exposure level has been established for avoiding adverse effects, nor has the Occupational Safety and Health Administration (OSHA) set an exposure limit. Though some pyrethroids have been banned from use in food production, they’re still used in lice treatments. Lice sprays used in airplanes, schools and homes (bedding, carpet, furniture, etc.) usually contain permethrin. The practice of spraying against lice is considered unwarranted and ill-advised by all the major health organizations. Don’t be fooled by claims that these pesticides are safe because they’re made from chrysanthemum flowers: they are chemically engineered to be more toxic with longer breakdown times and are often formulated with synergists, which increase potency and further compromise the body's ability to eliminate the pesticides.
Lindane, permethrin, pyrethrin and malathion are just some of the dangerous toxins used in popular lice treatments like Ovide, Nix, RID and Kwell. A study by French medical researchers, published in the journal Occupational and Environmental Medicine, found exposure to insecticidal shampoos doubled children’s risk of developing leukemia. No, it’s not a conclusive connection, but why take the risk? A 1993 study in Missouri found children treated with Kwell — which contains lindane — are five times more likely develop brain cancer than children not treated for lice. Reports made to the FDA's Med Watch Program on the use of various lice treatments include accounts of seizures, behavioral changes, neuromuscular complaints, birth defects, attention disorders, chronic skin eruptions, cancer and death. Approximately two-thirds of the reports were related to the use of lindane. What fun! We tend to presume that the chemicals found in our everyday products, food and water are thoroughly tested and regulated, or that “other” and “inert” ingredients are harmless. Basic, sound presumptions — but mistaken.
The safest option
What’s left? Nit-picking. Not the fast, easy solution any of us hope for, but it's reality. Even the most lethal lice treatments are not particularly effective (and are causing resistant “super-lice”). We need to stop thinking of these products as shampoos; they are insecticides.
To get rid of head lice, it's important to understand their life cycle. Repeated treatments are the norm. Eggs, or nits, hatch in 7-10 days and are more resistant than adults. They may require multiple treatments as they mature. To get rid of nits the first time 'round (and the second), fine-toothed combs, fingernails or tweezers are used. A tedious procedure, to be sure.
If you or your child gets head lice, remember that though lice are unpleasant, they neither transmit disease nor make us ill. The major hazard of head lice is enforced school absence. If your child’s school has a no-nit policy, refer its administrators to the American Academy of Pediatrics, whose guidelines explicitly discourage such policies, as does the Harvard School of Public Health.
Be prepared, stay calm and cultivate as much patience as you can muster. If there are natural remedies that look appealing to you, don’t wait until you’ve got lice in the house to purchase them. (We are much more likely to reach for poisons in a state of panic.)
When my kids came home crawling with lice, I turned to what we had on hand: olive oil, essential oils, rosemary and heat. A mixture of essential oils added to the kids’ shampoo left the carnage of lice floating in the tub. High heat (such as a hairdryer) seems to be effective, and is increasingly an option of choice. Oils (edible ones, not fossil) or mayonnaise can help suffocate lice, and at the very least make combing out nits easier. Tea tree, eucalyptus and lavender oils are celebrated for their anti-lice traits, and have worked well for my family. Tea tree is particularly effective but strong — a little bit goes a long way.
There's no need to go crazy cleaning and sterilizing everything in the house: Lice don't want to be, and cannot survive, anywhere but on you. If there are items you are concerned about — like hats, pillows or carseat covers — put them in the dryer on high for a cycle or two. Vacuuming can't hurt, but spraying certainly can. I think you'd be more likely to kill yourself than the lice.
Check out the CDC’s guidelines and the National Pediculosis Association’s Headlice website for general information and advice.
Photo: Paul Pellerito/Flickr