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This November 2000 NRDC report highlights the potential health hazards to humans and pets from flea collars and other flea and tick control products. The report recommends that the EPA ban the use of an entire class of these products -- those using organophosphates. It also offers recommendations for pet owners on combating fleas and ticks with a variety of simple non-chemical steps and/or by applying safer products, including insect growth regulators. The executive summary of the report follows; the complete report is available in Adobe Acrobat format (459k). Click here to get a free copy of the Acrobat Reader from Adobe.


Each year, Americans purchase and apply to their pets a vast array of toxic chemicals intended to kill fleas and ticks. These products are designed to poison insects, and they usually do just that. But they can also poison pets and the people who handle them. Moreover, when these products are combined in the home, as they often are, with other toxic chemical products in common use -- pesticides, herbicides, and other products -- they can pose a serious health risk, especially to children.

Adults are at risk from these flea and tick products as well -- pet workers who apply pesticides to animals on a daily basis, for example. But it is children who are most vulnerable. Because children's bodies are still developing, they can be more sensitive to the effects of toxic chemicals than adults. Studies with laboratory animals have raised concerns among scientists that children exposed to certain of the pesticides in pet products -- even at levels believed to be safe for adults -- face much higher risks, not only for acute poisoning, but also for longer-term problems with brain function and other serious disease. Moreover, children's behavior often makes them more vulnerable than adults. In particular, toddlers' hand-to-mouth tendencies make it easy for toxics to be ingested -- and not just by children who pet the family dog and then put their hands in their mouths. Children spend their time where the toxics from pet products tend to accumulate -- crawling on rugs, playing with pet toys, handling accumulations of household dust, and more.

Many and perhaps most Americans believe that commercially available pesticides, such as those found in pet products, are tightly regulated by the government. In fact, they are not. Not until the passage of a 1996 law focused on pesticides in food did the Environmental Protection Agency (EPA) begin examining the risks from pesticides in pet products in earnest. To this day, the EPA allows the manufacture and sale of pet products containing hazardous insecticides with little or no demonstration that a child's exposure to these ingredients would be safe. Just because these products are on store shelves does not mean they have been tested or can be presumed safe.

Of course, as bad as these products may be for pet owners and caregivers, they often are worse for the pets themselves. Based on the very limited data available, it appears that hundreds and probably thousands of pets have been injured or killed through exposure to pet products containing pesticides. As with small children, pets cannot report when they're being poisoned at low doses.

Healthier alternatives to these pesticides are readily available. Easy physical measures like frequent bathing and combing of pets can make the use of pesticides unnecessary. Pet products containing non-pesticide growth regulators also can stop fleas from reproducing successfully. In addition, newer insecticides, sprayed or spotted onto pets, have been developed that are effective against fleas and ticks without being toxic to the human nervous system. The safety and effectiveness of these alternatives makes the continued use of older, more toxic pet products tragically unnecessary.

Pet Pesticides at Work

Approximately 90 percent of American households use pesticides. According to one study, 80 percent of families surveyed have used pesticides at home even when a woman in the household was pregnant, and 70 percent have used them during a child's first six months of life. Half of the surveyed families reported using insecticides to control fleas and ticks on pets. More than a billion dollars a year are spent on flea and tick products.

Unfortunately, the wide use of these products is no indication that they are safe. Quite the contrary, the pesticides they introduce into the home include chemicals that are hazardous to the human brain and nervous system, chemicals that may disrupt the human hormone (endocrine) system, and pesticides suspected of causing cancer.

Flea control products now on the market include seven specific "organophosphate insecticides" (OPs). OPs work by blocking the breakdown of the body's messenger chemical, acetylcholine, thereby interfering with the transmission of nerve signals in the brains and nervous systems of insects, pets and humans alike. In the presence of OPs, acetylcholine builds up in the body. The resulting interference with nerve transmissions is of such a magnitude that it actually kills insects. In overdoses, OPs can also kill people and pets. But even with normal use of flea-control products containing OPs, pets and children may be in danger.

The seven OPs are chlorpyrifos, dichlorvos, phosmet, naled, tetrachlorvinphos, diazinon and malathion. They are the active ingredients in dozens of pet products. A comprehensive list of products appears in Table 1. It includes major pet pesticide brands, such as Alco, Americare, Beaphar, Double Duty, Ford's, Freedom Five, Happy Jack, Hartz, Hopkins, Kill-Ko, Protection, Rabon, Riverdale, Sergeant, Unicorn, Vet-Kem, Victory and Zema.

Organophosphate chemicals are also used on foods and in other common household products designed to kill non-pet-borne insects. For families exposed to these toxic chemicals, however, the route into the home and the specifics of how the chemicals work are less relevant than the plain fact that they pose a health threat. From a health standpoint, a person's combined exposure to one of these OPs, irrespective of its individual uses, is what is important. Further, because the various OPs all function by attacking the same chemical in the body, acetylcholine, exposure to a variety of OPs could have a combined impact.

The EPA's Role

Actual exposure of children and adults to OPs in pet products has not been adequately measured, and such studies have not been required of manufacturers seeking to put new pet pesticide products on the market. Indeed, until passage of the 1996 Food Quality Protection Act, EPA typically assumed there were no risks from these products, often with little or no scientific basis. In other words, EPA has allowed for decades the manufacture and sale of products containing pet pesticides without demonstration that a child's exposure to the products would be safe.

The 1996 law requires something new of EPA: that it estimate the accumulated effect on people of particular pesticides used on food products, accounting not just for exposure from foods, but from all sources. Since OPs used in pet products also are used on food crops, the law applies to these pesticides. Another provision of the law requires EPA to estimate the cumulative effect on a person from exposure to all pesticides and other chemicals that function in the same way. Because each OP functions by attacking the same chemical messenger in the body, home exposure to a variety of different OPs should be expected to have a cumulative health impact as well. The new law directs EPA to account for this cumulative effect in its risk assessments.

To date, EPA's compliance with the Food Quality Protection Act's provisions has been incomplete. Its risk assessments have been handicapped by flawed and inconsistent assumptions that have served to understate the risk from pet products. For example, in calculating risks of exposure to one chemical, EPA assumes that adults never hug their dog, and in a number of instances, EPA makes a variety of unrealistic assumptions about how long children spend in contact with their pets.

Moreover, four years after the enactment of the Act, EPA has yet to comply with the requirement that the Agency account for the cumulative impact of multiple OPs or of other chemicals that function in the same way. Here again, the result is risk assessments that understate the health hazards of exposure to the toxics in pet products. Finally, still today, EPA has never received adequate toxicity tests for these pesticide products long on the market. Of the seven chemicals that are the focus of this report, only one -- chlorpyrifos -- has been fully tested for its impact on a child's brain and nervous system. And, when the nervous-system testing for chlorpyrifos was recently completed, the results were so disturbing that the manufacturer itself took virtually all indoor uses of the chemical off the market.

Even with those important failings in EPA's methodology, the Agency's formal risk assessments for the seven OPs found both in pet and other products should alarm pet owners and parents: EPA now calculates that a child's exposure to individual OPs in pet products on the day of treatment alone can exceed safe levels by up to 500 times -- 50,000 percent. Exposures to children calculated over a longer period of time can exceed safe levels to an even greater degree. Were EPA to calculate the risks from these products using sound assumptions about how exposure to humans occurs in the real world, and/or were it to comply with the legal requirement that it calculate the cumulative effect of these OPs and of products that function similarly, EPA estimates of the risks from these products would be bleaker still.

The Natural Resources Defense Council is the first to put the individual risk assessments for pesticides from pet products side by side, highlighting the overall risks to children. EPA continues to look at these OP risks only one chemical at a time. The Agency has simply never gotten around to estimating the cumulative risks children face from the myriad uses of all the different OPs to which they are exposed. Once EPA does so, the cumulative risks are sure to exceed EPA's safe levels to a far greater degree.

The Risks

Though EPA's assessments of the risks from OPs in pet products are new, EPA has long identified OPs generally as being among the pesticides posing the highest risks to human health. Workers exposed to these chemicals, for example, have experienced visual problems, slowed thinking, and memory deficits. In truth, however, the principal risk for humans is likely to the brain and nervous system of young children and fetuses, because their systems are still developing when they are exposed to OPs. The risks come in two forms: risks from poisoning, and risks from long-term effects on the brain and nervous system.

  • Children's Risk of Acute Poisoning. OPs are considered the most dangerous pesticides for acute poisoning, particularly for children younger than six. Among incidents reported to poison control centers, children exposed to OPs were three times more likely to be hospitalized, five times more likely to be admitted to a critical care unit, and four times more likely to die, suffer life threatening illness, or develop a permanent disability, than were children who had been exposed to other types of pesticides.

  • Children's Long-term Health Effects. A child's developing brain and nervous system are particularly vulnerable to the toxic effects of OPs because these systems are not fully developed at birth and must continue to form during early childhood. Brain development requires certain cells to first grow, then migrate within the brain, and then connect with one another. Chemicals such as OPs can interrupt and have irreversible effects on this development. Studies have also shown that children exposed to OPs may face increased risks for such later-in-life problems as cancer and Parkinson's disease. A recent epidemiological study, for example, showed that people with any history of in-home exposure to insecticides, like OPs, can more than double the risk of Parkinson's later in life. In addition, four OPs used in pet products increase cancers in laboratory animals, and therefore may cause cancer in humans. One epidemiological study that looked, among other things, at pregnant women who had been exposed to flea and tick products, found that their children were 250 percent more likely than those in a control group to be diagnosed with brain cancer before their fifth birthday.

Of course, it is not only children who are at risk. Pets and pet workers are vulnerable as well.

  • Pet Poisonings. In recent years, hundreds, if not thousands, of pets have been poisoned by pesticide products specifically designed for use on pets. Products containing OPs are among the worst culprits. EPA finds that these pet products are frequently misused and that such misuse should be anticipated by manufacturers. Cats are particularly vulnerable, since they often lack key enzymes for metabolizing or detoxifying OPs. As with children, a cat's small size and unique behavior -- in this case, grooming -- work against them as well, making them particularly vulnerable to OP poisoning.

  • Pet Worker Poisonings. Over a recent four-period, at least 26 adults working with pesticide pet dips were poisoned. Nearly half of these cases involved the OP, phosmet. Moreover, a survey of nearly 700 adults who worked with flea control products found that these workers were two-and-a-half times more likely to have health problems than workers not exposed to such products. The complaints included statistically significant increases in blurred vision, skin flushing and asthma.

Although each of the OPs we looked at has unsafe pet uses, the properties of these products vary, and so they pose somewhat different threats to the people exposed to them. Some examples:

  • Pets "dipped" with phosmet. Toddlers who pet a large dog the day of its treatment and then put their fingers in their mouths will receive more than 500 times the safe level of this chemical, according to EPA estimates.

  • Flea collars containing dichlorvos (DDVP). EPA's preliminary estimates are that toddlers exposed to pets wearing flea collars containing dichlorvos would be exposed to 21 times the safe level just from inhalation of the insecticide emitted from the collar. Adults exposed to the same product would experience exposures ten times greater than safe levels.

  • Flea collars containing naled. EPA found no uses of naled flea collars that are safe for children ages eight and under. Toddlers' exposures were calculated to be as much as ten times more than EPA's safe level.

  • Flea collars containing chlorpyrifos. EPA estimates that a toddler exposed to a dog wearing these collars could get more than seven times the level EPA considers to be safe merely from hugging or petting their dog.

  • Pets sprayed or dusted with tetrachlorvinphos. EPA finds that toddlers exposed to medium- or large-sized dogs that have been sprayed or dusted with tetrachlorvinphos products could face exposures nearly twice as high as EPA's safe level.

  • Dipping or powdering pets with tetrachlorvinphos. EPA determines that powdering or dipping a single pet with tetrachlorvinphos just twice a year would, over the course of a lifetime, pose a risk of cancer to the person dipping the pet nearly six to seven times higher than acceptable EPA levels. Dipping or powdering multiple pets, or doing so more frequently, would raise cancer risks even higher.

Safer Alternatives

The continued exposure of children, pets and animal workers to OPs contained in pet products is all the more distressing because safer alternatives are readily avail-able. Easy physical measures alone, like frequent washing and combing of the pet and vacuuming carpets and furniture, can bring mild flea infestations under control. Alternatives include insect growth regulators, or IGRs, which are not pesticides, but rather chemicals that arrest the growth and development of young fleas. These include methoprene, fenoxycarb and pyriproxyfen and the popular lufenuron (Program®). Alternatives also include newer pesticide products sprayed or spotted onto pets, such as fipronil (Frontline®) or imidacloprid (Advantage®). Particularly when used in combination with physical measures, the safety and effectiveness of these newer chemical products makes the continued use of pet products containing OPs -- and their attendant risks for humans and pets alike -- rash and unnecessary.


The threats posed to humans and pets by OPs in pet pesticides are intolerable. The Natural Resources Defense Council recommends the following:

  • Pet owners should begin using safer products on their pets, avoiding OP-based pet products. Safer products are best combined with such simple physical measures as brushing pets regularly with a flea comb while inspecting for fleas, and mowing frequently in areas where pets spend the most time outdoors.

  • Pregnant women and families with children should cease using OP-based products immediately.

  • Children should never apply flea shampoos, dusts, dips, etc. containing OPs to their pets. EPA has overlooked and underestimated the particular risks to children when evaluating the safety of these products for home use.

  • Retailers should remove OP products from their shelves and seek to educate customers about the merits of safer alternatives.

  • EPA should move immediately to ban the use of pet pesticides containing OPs.

  • EPA should consider also banning pet products that contain carbamates -- a class of insecticides closely related to OPs, and sharing with OPs the same basic biological mechanism of harm. Likewise, homeowners and retailers should avoid the purchase and sale of these carbamate-containing products.

  • EPA should take steps to better inform veterinarians, pet owners and the general public about safer alternatives for the control of fleas and ticks on pets.

For most pet owners, the family dog or cat is a beloved member of the family. Unfortunately, products often used to protect pets from fleas and ticks carry serious health hazards -- not just for the pets, but for the children who play with them, care for them, and love them. Safer alternatives are available -- alternatives that will effectively protect pets from insects without introducing intolerable health hazards into the home. Consumers, manufacturers, veterinarians, retailers and the government all have an important role to play in eliminating these risky pet products and bringing safer alternatives into common use.

EPA Registered Pet Products Containing Organophosphates Insecticides
Insecticide Dog Product Cat Product
Chlorpyrifos Zema 11-month collar* Sulfodene Scratchex Flea and Tick Collar for Cats*
Sergeant's Flea + Tick Collar Happy Jack 3-X Flea, Tick And Mange Collar For Cats
Sergeant's Fast-Acting Flea & Tick Collar For Dogs Victory II Full Season Cat Collar
Hartz 330 Day Flea & Tick Collar For Dogs  
Sandoz Dursban Collar For Dogs (RF-9411)
Methoprene/Chlorpyriphos Combination Collar For Dogs
Happy Jack Tri-Plex Flea And Mange Collar
Sulfodene Scratchex Flea And Tick Collar For Dogs
Victory 12 Full Year Collar With Dursban For Large Dogs
Dichlorvos Sergeant's Sentry Collar For Dogs Sergeant's Sentry Collar For Cats
Sergeant's Fast-Acting Flea & Tick Collar For Dogs Flea Collar For Cats
Sergeant's Dual Action Flea And Tick Collar For Dogs Alco Flea Collar For Cats-White
Flea Collar For Dogs Alco Flea Collar For Cats-Clear
Alco Flea Collar For Dogs - Black, Clear & Glitters Alco Flea Collar For Cats-Glitters
Freedom Clear Dog Collar Freedom Clear Cat Collar
Naled Sergeant's Sentry IV Flea & Tick Collar (for dogs)* Sergeant's Sentry IV Flea & Tick Collar*
Sergeant's (R) Sentry V Flea & Tick Collar For Dogs* Sergeant's (R) Sentry V Flea & Tick Collar For Cats*
Sergeant's Flea + Tick Collar*  
Phosmet Unicorn Insecticidal Dust*  
Vet-Kem Kemolate Emulsifiable Liquid* (for dipping)
Tetrachlorvinphos Hartz 2 In 1 Collar For Dogs* Hartz 2 in 1 Collar for Cats*
Hartz 2 in 1 Flea and Tick Control Collar with 14.5% Rabon* Hartz 2 in 1 Plus Long Lasting Collar for Cats*
Hartz 2 In 1 Plus Seven Month Collar For Dogs* Hartz 2 in 1 Plus 7-month Collar for Cats*
Hartz Rabon Collar With Methoprene Hartz Rabon Collar With Methoprene
Americare Rabon Flea & Tick Collar For Dogs Americare Rabon Flea & Tick Collar For Cats
Rabon Dust For Dogs And Cats Rabon Dust For Dogs And Cats
Hartz 2 In 1 Flea & Tick Powder For Dogs* Hartz 2 in 1 Flea & Tick Powder for Cats
Clean Crop Livestock 1% Rabon Dust Clean Crop Livestock 1% Rabon Dust
Hartz 2 In 1 Flea & Tick Pump For Dogs II Hartz 2 In 1 Flea & Tick Pump For Cats II*
Hartz Rabon Spray With Methoprene Pump Formulation Hartz Rabon Spray With Methoprene Pump Formulation*
Hartz Rabon Flea and Tick Dip for Dogs and Cats* Hartz Rabon Flea and Tick Dip for Dogs and Cats*
Hartz 2 In 1 Flea And Tick Spray With Deodorant For Dogs III*  
Hartz Flea and Tick Repellent, containing 1% Rabon*
Malathion Kill-Ko Malathion Concentrate Kill-Ko Malathion Concentrate
Riverdale Malathion 5 Riverdale Malathion 5
Ford's 50% Malathion Emulsifiable Concentrate SMCP 5% Malathion Dust
SMCP 5% Malathion Dust Hopkins Malathion 57% Emulsifiable Liquid Insecticide-B
Hopkins Malathion 57% Emulsifiable Liquid Insecticide-B 50% Malathion Emulsifiable Concentrate
50% Malathion Emulsifiable Concentrate 55% Malathion Concentrate
55% Malathion Concentrate 50% Malathion
50% Malathion Micro-Gro Cythion Premium Grade Malathion E-5
Micro-Gro Cythion Premium Grade Malathion E-5 Fyfanon 57 EC
Fyfanon 57 EC  
Diazinon Protection 150 Reflecting Flea And Tick Collar For Dogs Protection 150 Reflecting Flea And Tick Collar For Cats
Protection Plus 150 Flea And Tick Collar For Dogs With EFA Protection Plus Flea And Tick Collar For Cats
Protection 150 Flea And Tick Collar For Dogs And Large Dogs Protection 150 Flea And Tick Collar For Cats
Protection 300 Flea And Tick Collar For Dogs Double Duty Plus Flea & Tick Collar With Nutrisorb For Cats
Diazinon-Pyriproxyfen Collar For Dogs And Puppies #1, #2, #3 Double Duty Reflecting Flea & Tick Collar For Cats
Double Duty Plus Flea & Tick Collar With Nutrisorb For Dogs Freedom Five Flea And Tick Collar For Cats
Double Duty Reflecting Flea & Tick Collar  
Freedom Five Flea And Tick Collar For Dogs
Beaphar Tick & Flea Collar For Dogs
Double Duty Flea & Tick Collar For Dogs
Source: James Beech, U.S. EPA Office of Pesticide Programs, Pet Products Registered for Seven Organophosphates, June 3, 2000.

Note: Products in regular type are those registered with EPA as of June 3, 2000. Asterisks indicate pet products known to form the basis for EPA's risk assessment for that chemical. Dichlorvos, diazinon and malathion risk assessments did not list particular products. Italicized products are those for which, subsequent to the risk assessment, manufacturers now indicate they will no longer maintain registration of the product. In most, if not all such cases, however, the products remain in use at the time this report was prepared.

If you think you or your pet has been affected by a pet product containing pesticides, call your local poison control center if you need immediate help, and report the incident to the EPA's National Pesticide Telecommunications Network, at (800) 858-7378.

last revised 11/1/2000

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