|Example of a pest strip with dichlorvos.|
|Check product label for the organophosphate, dichlorvos, listed as an active ingredient.|
Pest strip products containing the ingredient dichlorvos (also called 2,2-dichlorovinyl demethyl phosphate or DDVP) are available for sale to consumers and pest control professionals for a wide variety of uses. The strips release an insecticide vapor and last for up to four months. Dichlorvos is an organophosphate pesticide. Most other organophosphate pesticides have been canceled for indoor residential use to reduce health risks to infants and children.
Organophosphate pest strips (strips that contain dichlorvos) are legal, but we are concerned they are making people sick, especially if they are not used according to their directions. We are working with regulatory agencies and the manufacture of pest strips to improve warnings for consumers and make the restrictions about occupied areas more clear on the product label.
From 2000 to 2011, we documented five possible cases of illness following use of pest strips. Within just the first half of 2012 (January-June), five additional cases were reported. These people visited a doctor, hospital, or called the Washington Poison Center. The symptoms were generally headache, coughing, nose and throat irritation, nausea, and fatigue. Although the people's symptoms were consistent with exposure to dichlorvos, we were unable to medically confirm that the illnesses were caused by the pest strips.
- A woman bought pest strips to control mosquitoes in her home. She read on the label, “lasts up to four months and good for use in cabins.” She didn't see that the product was not to be used in indoor spaces occupied for more than four hours per day. She hung a strip in her living room and bedroom. After the fourth day, she developed headache then stomach problems that lasted for several days after she removed the strips.
- A family bought pest strips to control bedbugs and tried to mimic a study they found online. They heated the strips in bedrooms, made sure not to sleep in the rooms during the treatment, and ventilated the rooms after removing the strips. Family members reported respiratory problems and stomach problems for several weeks whenever they stayed in their home. Heating the strips releases insecticide vapor at a faster rate and could cause unsafe levels in the air. Their home's heating system also probably circulated the vapors throughout the home.
- A woman bought three pest strips to control flies. She opened the packages in her home and immediately smelled an odor, felt nauseated, and burning in the back of her throat. She called the poison center and got fresh air. Opening packages outdoors could minimize this problem.
Problems to Avoid
Our interviews with sick people revealed common mistakes that resulted in over-exposure to the pest strips. These common mistakes are also evident in online consumer reviews at internet purchase sites.
Hanging Too Many Pest Strips
Too many pest strips can be harmful. If you hang too many in a closet or pantry, the vapor released could reach harmful levels in nearby rooms. Be sure to read and follow the directions on the product label.
Hanging Pest Strips in Occupied Areas of the Home
Some people are confused by the directions on the product label. The label states that the product can be used in garages, attics, and sheds as long as they are not occupied by people for more than 4 hours per day. The strips should not be used in general living or sleeping areas.
The label also says the pest strips can be used in vacation homes, cabins, and mobile homes - but only if “unoccupied for more than four months immediately following placement of pest strip."
Improper Disposal of Pest Strips
If you need to remove a strip that is partially full, consult your local solid waste management facility for disposal instructions. It may be necessary to take the unused product to your local household hazardous waste facility. Avoid contact with skin when removing strips.
People may not realize that overuse or misuse of pest strips could make them or their family sick. There are few warnings on the label. Dichlorvos attacks an important enzyme in the nervous system of insects and humans. People can get sick from breathing too much pesticide vapor in the air. Early symptoms of overexposure in people include headache, lack of appetite, nausea, vomiting, and difficulty breathing. The pesticide can cause more serious nervous system symptoms if exposure continues. Children have higher breathing rates than adults and may absorb more of the chemical vapor.
There may be long-term health impacts from household use of organophosphates. A number of animal studies have shown that other organophosphate insecticides, similar to dichlorvos, can impair normal brain development and function if exposure occurs early in life. Recent studies in people report that mothers with higher exposures to similar organophosphate insecticides during pregnancy had children who performed lower on intelligence and memory tests and had higher rates of behavioral problems such as ADHD.
Alternatives to Pest Strips
We encourage people to use safer alternatives to pest strips. Below are some examples of integrated pest management (IPM) strategies. For more home management of pests, see University of California's IPM Online.
Prevent flies from entering a home with screens and other physical barriers.
Identify and clean up the source of insect attraction and breeding (such as garbage cans and manure piles). Without proper sanitation, the pests will continue breeding and making their way into the home.
Use physical traps (sticky paper).
Use traps with insect attractants.
For more information see How to Manage Flies, University of California.
Bed bug prevention and tips for getting rid of them.
Health Effects of Dichlorvos
|Content Source: Pesticide Program|