Thursday, April 1, 2010

Pesticides, Urine and Vacuum Dust: What’s the Connection?

Dust is nearly as ubiquitous as the wind, floating and flying into every crevice of our lives. It begins as a speck of dirt or a couple of hairs, and as it settles over every surface, it clings together as a fuzzy blanket or a furry tumbleweed. That blanket—and every particle that binds it together—holds evidence of what you breathe each day.

That evidence inspired Dr. James Starr to conduct a study on what was in the dust in people’s homes. A physical research scientist with the U.S. Environmental Protection Agency, Starr was particularly interested in a specific ingredient that he suspected he would find in the dust—pesticides.

According to Starr, almost no one can avoid the presence of pesticides. The neatest, most compulsive housekeeper who eats organic food and shuns furry companions may provide even the slightest exposure to pesticides in the air. Most times, the exposure goes unnoticed. Although most people won’t ingest even a fraction of the pesticides needed to make them sick, the Centers for Disease Control and Prevention periodically assesses people’s exposure to pyrethroid pesticides by examining their urine. Pyrethroids are a type of pesticide commonly used to control insects on farms, in homes and on pets.

When someone uses a pesticidewhether it’s a shot of ant or roach spray in a corner or a flea product on a dog—that pesticide remains where it is applied. Once it enters the environment, the original parent pesticide, and the altered compounds that comprise it—called degradates—enter the body with a breath or a bite of food, may be further metabolized, and may exit the body through the urine.

In the urine, Starr says, the metabolized parent pesticide and the degradates look identical when they are analyzed. Starr wanted to know if urinary analyses were accurately measuring the amount of the original pyrethroids in a person’s body or if some of the person’s exposure came from the less toxic degradates. If people were inhaling both the parent pesticide and the degradates, results from urinary analyses would be unnecessarily alarming. So he decided to test dust samples vacuumed from people’s homes.

“We’re interested in dose, the follow-up to exposure,” Starr says. “That’s where the chemicals have the ability to have an effect.” The greater the toxicity of a substance and the more that’s ingested, the more likely the substance is to have an effect.

To purify the dust samples, Starr sent them to a lab in Maryland to be zapped with gamma radiation. Dust is as nasty as it seems; it’s a collection of skin cells, bacteria, hair, dirt, and any other particle flying around in the air. Starr says he only works with dust inside a fume hood.

“If you can smell the contents of the bag when you vacuum, you are redistributing dust throughout your home,” he says.

The pyrethroid products in the dust samples—in doses too miniscule to likely be harmful—included the degradates.

“This shows that exposure can be to the degradates in addition to the parent compound,” says Starr. “If you don’t know which, you may overestimate exposure to the more harmful parent.”

Thanks to Starr, we can all breathe easier.

Reference: Starr, J., Graham, S., Stout, D., Andrews, K. and Nishioka, M. Pyrethroid pesticides and their metabolites in vacuum cleaner dust collected from homes and day-care centers. Environmental Research, 108 (2008) 271-279.

4 comments:

  1. It would be interesting to compare exposure to pesticides in large cities (like here in Toronto, Canada)that have banned their use.

    ReplyDelete
  2. Especially timely, now that the pine trees are shaking pollen into the air (adding to the dust) like salt shakers with too-big holes.

    ReplyDelete
  3. I am not sure about using word "urine" in the title. Don't know if it has any fans. I was turned away from the article.

    ReplyDelete
  4. Informative! My son (who loves science) was initially drawn to the blog's title but remained interested because of the content.

    Dr. Starr has provided a valuable public service.

    PS. Maksym, Urine, urine, urine!

    ReplyDelete