Some thoughts about pesticides
published in the Sun July 14, 2012

Dr. Maggie Stummer and Schnitzel, who is flea-free

At veterinarian Maggie Stummer’s home there are at least three dogs, two cats, a cow and calf, two rabbits, plus a flock of chickens, ducks, and baby turkeys.  I have come to visit with her about flea collars.  When Dr. Stummer sees a dog or cat wearing a flea collar she pulls it off and throws it in the trash.  A flea collar works by coating the animal’s fur with insecticide.  The insecticide is licked off by the pet and rubbed off by anyone who touches the pet.  Not only can flea collar insecticides be toxic to the animal, but Dr. Stummer wonders why anyone would risk exposing their children, who hug and kiss the pet, and maybe even sleep with it.  She prefers flea medications given by mouth.  “The oral products are safe and your kid doesn’t touch it.”

Most of us don’t like insects very much, so we have invented insecticides to kill them.  I’ll admit that when wood ants threatened to turn my dining room into a pile of dust last week even yours truly grabbed a can of Raid.  The problem is that insects and humans have a lot in common.  We are both carbon-based life forms with DNA, for example.  A chemical that is poisonous to a bug will likely have some bad effects on people as well.

Many flea collars are impregnated with the organophosphate tetrachlorvinphos.  Organophosphates are a class of insecticide that interferes with the neurotransmitter acetylcholine.  Insects and humans both use acetylcholine as a chemical signal from nerve cells to muscles, releasing just enough acetylcholine to cause purposeful movement.  When an insect is exposed to an organophosphate, acetylcholine floods the synapse and the insect twitches uncontrollably until it dies. Luckily people and dogs are much bigger than insects, so a fatal dose of organophosphate for a bug is a tiny dose for us.  If you got a dose proportional to your body weight, you too would lie on your back and twitch.  Sarin nerve gas, an organophophate, was one of the chemical agents used by Saddam Hussein to massacre Kurds in 1988.  Worldwide about 300,000 people die every year from exposure to organophosphate pesticides, and 3 million become ill.  Organophosphate exposure has been linked to attention deficit disorder in children.

The other day a salesman came to my door and asked if I have bugs in my house.  Of course we have those tiny spiders that catch bugs in the corners and make those little spots on the floor so I said yes.  He offered to come in and spray, but I told him we prefer a few spiders to toxic chemicals.  He told me, “It’s not toxic – it’s made from chrysanthemums,” conjuring up the wholesomeness of a homecoming queen.  I still preferred spiders.  The salesman realized he was dealing with a nutjob and left to search for a more meticulous housekeeper.  But let me explain this chrysanthemum thing.

Chrysanthemums contain an organic neurotoxin called pyrethrum.  During the Napoleonic Wars, French soldiers used powdered pyrethrum to control fleas and lice.  Pyrethrum is still available today, but chrysanthemum powder was NOT what the salesman wanted to spray in my house.

He wanted to use a pyrethroid, which is a synthetic insecticide similar in action to pyrethrum.  Pyrethroids are found in many, many household products and can be recognized by a chemical name that ends in “thrin.”  Pyrethroids have largely replaced organophosphates in bug sprays for home use because they are generally considered safer for people.  Safer, but not totally safe.

Pyrethroids are used in large doses on lawns to treat fire ants, mosquitoes, chinch bugs, et cetera.   Insecticides on the lawn are very effective.  They kill all the insects, both good and bad, and leave nothing for the birds and lizards to eat, creating an ecological wasteland.  Even though these lawn treatments are supposed to be safe for pets, every week Dr. Stummer sees dogs that develop vomiting and diarrhea two or three days after their yards are treated.  Cats are especially sensitive and can be killed by a dose that would be safe for a dog.  Pesticides for the yard are formulated to persist for months, so animals and people continually track the residue into the house.  Children crawl on the floor and contaminated little hands go into little mouths.  In lab animals pyrethroids can cause thyroid, liver, and nerve damage.  They can also act as endocrine disruptors, affecting reproductive development and stimulating breast cancer cells.  Pyrethroids are frequently combined with piperonyl butoxide, a chemical which increases effectiveness by inhibiting an insect’s ability to detoxify the pyrethroid.  A study at Columbia in 2011 showed that children exposed to piperonyl butoxide in utero had a drop in IQ equal to that caused by lead poisoning.  Dr. Stummer worries about this chronic low level exposure of our children to multiple pesticides, which may be present not only in the home but also on food sprayed at the farm.  “What are we going to know in 30 years?”

Here are Dr. Stummer’s general suggestions about insecticides:

1.  Avoid flea collars, except on rare occasions such as hunting trips.

2.  Check with your veterinarian for appropriate formulations and dosages before treating your pet.

3.  Avoid spraying your whole house or yard with pesticides.

4.  If you must use a pesticide for an out-of-control situation, learn to do it safely and spot treat the involved area only.

5.  Change your attitude about bugs.  Small crawly things are not our enemies, and can be beneficial.  We are all in this together.