Perils of the New Pesticides

Published — July 30, 2008 Updated — May 19, 2014 at 12:19 pm ET

‘Safe’ pesticides now first in poisonings

EPA data shows that the number of reported human health problems increased by about 300 percent over the past decade


Two-and-a-half-year-old Amber Nickol McKeown had head lice. Her mother, Eileen, put the child in a warm bath and massaged Osco Lice Treatment Shampoo into her scalp. Problem solved.

But when Eileen lifted Amber from the tub, she noticed her daughter’s chest had turned red. She called her husband, James, upstairs, and the couple tried bathing Amber in cool water. The little girl’s condition deteriorated quickly. She labored to breathe. Her eyes rolled back in her head, and her skin peeled off in clumps, according to a lawsuit filed by the family.

Amber was rushed from her home in Lester, Pennsylvania, to Fitzgerald Mercy Hospital, where the staff found burns over 60 percent of her body. She was in respiratory distress, and her heart and lungs couldn’t supply her body with oxygen.

On November 4, 2000, within 72 hours of her bath, Amber was dead. After performing an autopsy, the Delaware County (Pennsylvania) medical examiner concluded that the child’s death had been triggered by exposure to a type of pesticide called a pyrethrin and its accompanying impurities, according to the family’s lawsuit.

Pyrethrins, extracted from the chrysanthemum plant, and their synthetic relatives,pyrethroids, have exploded in popularity over the last decade. They are now used in thousands of consumer products from Hartz Dog Flea & Tick Killer to Raid Ant and Roach Killer. These chemicals are found in bug-repellant clothing, flea collars, automatic misting devices, lawn-care products, and carpet sprays. Manufacturers developed them as safer alternatives to a class of compounds, derived from Nazi nerve gases, called organophosphates, found in products such as Dursban. The chemicals were widely used in American homes as recently as the late 1990s but are no longer approved by the Environmental Protection Agency for indoor use.

An analysis of EPA data by the Center for Public Integrity, however, shows that the number of reported human health problems, including severe reactions, attributed to pyrethrins and pyrethroids increased by about 300 percent over the past decade. A Center review of the past 10 years’ worth of more than 90,000 adverse-reaction reports, filed with the EPA by pesticide manufacturers, found that pyrethrins and pyrethroids together accounted for more than 26 percent of all fatal, “major,” and “moderate” human incidents in the United States in 2007, up from 15 percent in 1998. Although the number of fatalities was low — about 20 from 2003 to 2007 — the amount of moderate and serious incidents attributed to the group — more than 6,000 — is significantly greater than any other class of insecticide.

The EPA’s pesticide incident-reporting system has not been public until now. Called one of the “Ten Most Wanted Government Documents” by the Center for Democracy and Technology, the database was released under the Freedom of Information Act to the Center for Public Integrity in early 2008.

Data from the American Association of Poison Control Centers show a similar trend as the EPA data, with the number of pyrethrin and pyrethroid incidents reported to poison centers jumping from about 16,000 in 1998 to more than 26,000 in 2006 — a 63-percent increase. The data include all phone calls and other incidents reported to the centers. Experts say that both the EPA and the poison center data probably represent only a fraction of pesticide-related exposures in a given year.

EPA Investigation

Debra Edwards, director of the EPA’s Office of Pesticide Programs, said the agency had not planned to examine the health effects of the chemicals until 2010, but would expedite the process as a result of the Center’s investigation. “I’m going to ask that we do a broad report on pyrethrin and pyrethroid incidents to see if we can determine anything about trends,” she said in a recent interview.

The 300-percent increase in reported incidents — from 261 in 1997 to 1,030 in 2007 — appears to be largely due to the growing popularity of pyrethrins and pyrethroids. Despite the common belief that these insecticides are less toxic than organophosphates and that fatal incidents are rare, some scientists and physicians have begun to question their safety — especially for people with asthma or allergies. There are also worries about the compounds’ effects on the nervous system, particularly among infants and children.

“These are definitely not benign agents,” said Delaware County Medical Examiner Frederic Hellman, who performed the autopsy on Amber McKeown.

Hellman declined to discuss the details of that case, but said that significant numbers of people may be sensitive to pyrethrins and pyrethroids and experience an anaphylactic reaction (a severe, whole-body allergic reaction) resulting in skin or respiratory disorders and in extreme cases death. The medical literature, including some recent studies, suggests that people with ragweed allergies and asthma may be particularly sensitive to pyrethrins and pyrethroids. Up to one in five Americans are susceptible to ragweed allergies. Pyrethrins are extracted from chrysanthemum plants and like the plant can trigger allergic reactions in some people.

When his children got head lice on a camping trip, Hellman said, he relied on Vaseline and plastic wrap to smother the lice. His wife then used a fine-toothed comb to pick out the insects’ bodies and eggs. “We weren’t about to use the shampoos,” Hellman said. “Perhaps for some people they’re fine, but for others they’re definitely not.” He recommends that anyone considering using pyrethrin or pyrethroid products consult a physician in advance.

“These are definitely not benign agents,” said Delaware County Medical Examiner Frederic Hellman.

Representatives of SC Johnson, the manufacturer of Raid and other products containing pyrethrins and pyrethroids, and the Hartz Mountain Corporation, maker of pet products containing the compounds, declined to comment. Toxicologist Tom Osimitz of the Pyrethrins Joint Venture, an industry program, said that pyrethrins and pyrethroids do not present any known long-term health risks because people tend not to be exposed to the chemicals for long periods, and when they are exposed eliminate the pesticides from their bodies relatively quickly. Osimitz is a former vice president of global safety assessment and regulatory affairs for SC Johnson; he also was retained as an expert defense witness in the lawsuit brought by Amber McKeown’s parents, but said he could not discuss the case.

The rising number of pyrethrin and pyrethroid incidents should not be a concern, Osimitz said, because most people who call poison centers about those insecticides either don’t have symptoms or are experiencing minor effects. American Association of Poison Control Centers data show that the majority of incidents are minor. But association figures also show that the number of pyrethrin and pyrethroid exposures resulting in medical treatment is climbing, and is approaching the number of hospital trips resulting from organophosphate exposures at their peak in the early 1990s.

Even experts skeptical of pyrethrin and pyrethroid safety do not advocate banning residential use of the insecticides. Instead, researchers urge more thorough studies and more specific warning labels and, in some cases, recommend that the chemicals be applied only by trained professionals.

Warning Labels

Critics say the EPA’s Office of Pesticide Programs can be slow to act on emerging health threats and is sometimes intimidated by the chemical and agricultural industries. The agency’s Edwards counters that these detractors may confuse the department’s methodical approach to regulation with inaction. Although the agency occasionally negotiates or orders immediate product recalls, it often opts for phase-outs — which can take years — for “high benefit” chemicals. In either case, Edwards said, “We focus all of our priorities and decision-making on protecting public health and the environment.”

But Jerome Blondell, a former health statistician in the EPA’s pesticide office, urged in a 2005 memorandum to his superiors that makers of certain products containing pyrethrins and pyrethroids be required to put explicit warnings on their labels regarding the possibility of severe reactions for people with ragweed allergies or asthma. Blondell recommended a warning such as: “This product may cause bronchospasm in susceptible individuals. Patients with a history of asthma or ragweed allergy should consult their physician prior to use.” The idea was rejected, he said.

Blondell, who retired in 2005 after 30 years with the agency, said he was especially troubled by reports of people being sprayed with the pesticides by automatic misting devices, used to kill insects by some fast-food restaurants.

“I was getting complaints of people who were sprayed in the face, and it was my position that people should not be sprayed in the face with a pesticide,” he said. “Their [EPA officials’] position was, ‘Oh, my gosh,’ when they heard names like McDonald’s and IHOP. They saw these tremendous markets, and they didn’t want me to interfere with them, so we never got anywhere with that. I was always very annoyed about that. The whole thing — it was just a bureaucratic foul-up.”

Dr. Geoffrey Calvert, a senior medical officer with the National Institute for Occupational Safety and Health, worked with Blondell to place stricter labeling on misting devices. After Blondell retired, “There was no one to carry on the battle,” Calvert said. “And before he left, he was hitting a brick wall.”

The EPA’s Edwards acknowledged that the agency did not act on Blondell’s and Calvert’s recommendations. Instead, she said, in 2006 the EPA ordered labeling changes that are actually better than what the two men proposed. “He [Blondell] was focusing his label change recommendations on people that had allergies and asthma,” she stated. “What we have required on the label is: ‘Do not enter or allow others to enter until vapors, mists, and aerosols have dispersed and the treated area has been thoroughly ventilated.’ That was not on the products before.”

In 2003 the EPA considered requiring a more specific warning for sensitive populations after Jacqueline Mosby, then an environmental scientist in the Office of Pesticide Programs, presented an unpublished master’s thesis linking pyrethrins and pyrethroids to acute reactions in people with allergies and asthma, Edwards said. Mosby’s analysis suggested that the odds of these insecticides causing respiratory reactions are two-and-a-half times as great as for other pesticides. Mosby also found a slight but statistically significant association between pyrethrins and pyrethroids and skin ailments.

The EPA backed off the labeling requirement after the industry’s Pyrethrin Task Force, composed of manufacturers of pyrethrin products, conducted a study that determined allergic responses or asthma occurred less frequently in people exposed to pyrethrins than in people exposed to other pesticides, Edwards said. An accompanying pesticide industry review of medical literature also dispelled any link between adverse skin reactions in people with allergies and pyrethrin and pyrethroid exposure, according to Osimitz, the former SC Johnson employee who helped write the review for the task force. Dr. Ruth H. Allen, an EPA epidemiologist, however, wrote in a report that the review’s conclusions were not substantiated by the evidence presented. “The authors state that based on current chemistry and the current level of diagnostic standards, allergic contact dermatitis does not occur in response to . . . pyrethrin ‘at a significant incidence in either ragweed sensitive individuals or otherwise,’” Allen wrote, “but they do not provide the detailed evidence to support this conclusion.”

Studies tying pyrethrins to respiratory and skin reactions among asthmatics and other populations date to the early 20th century. Osimitz said that the crude pyrethrin extracts used decades ago may have caused allergic reactions because they contained impurities. Today, he said, the impurities are removed by more sophisticated refining techniques.

The Food and Drug Administration, which regulates shampoos containing pyrethrins and pyrethroids, has recognized the pesticides’ potential harm for more than 15 years. Beginning in 1993 the FDA required anti-lice shampoos to carry a warning regarding the possible effects on people with ragweed allergies, and in 2003 it ordered the language strengthened to echo what Blondell proposed. “Ask a doctor before use if you are allergic to ragweed,” the FDA warning states. “May cause difficulty breathing or an asthmatic attack.”

A warning on anti-lice shampoos “probably makes sense” considering that consumers usually apply the pesticide directly to the skin and may use too much, the industry’s Osimitz said. But for bug sprays, which are applied broadly to a room, and other EPA regulated products, he argued that warnings could be counterproductive, causing alarm over what he says are relatively harmless products.

“So you put a warning on a product that says, ‘Consult a physician before use.’ I don’t know a pediatrician or a general practitioner who’s up on pyrethrins,” Osimitz said. “What are they going to do when I ask, ‘Should I use pyrethrins?’ What happens is you get pretty blasé to those warnings. Everything has a warning. What’s real and what’s not? I’m going to miss the things that are real.”

Toxic Effects

The EPA’s pesticide incident-reporting system receives up to 6,000 reports annually — ranging from pet poisonings to water contamination — and is rarely able to confirm the details. Many of the reports are quite specific, however, and include breathing difficulties, peeling skin, hives, vomiting, and muscle aches tied to pyrethroids and pyrethrins. The data show that at least 50 deaths have been attributed to the chemicals since 1992 — 20 of them since 2003. In her master’s thesis, Jacqueline Mosby, now a branch chief with the EPA toxics program, used EPA and American Association of Poison Control Centers data, as well as reports in scientific and medical journals, to document the deaths of four people following pyrethrin or pyrethroid exposures: a 37-year-old woman who died after she gave her dog a flea bath, a 39-year-old woman who died after applying a flea treatment to her two dogs, an 11-year-old girl who died after washing her dog with a pet shampoo, and a 48-year-old woman who died after using a bug spray.

There are also concerns about long-term, chronic effects, which would not be reflected in the EPA data. Some researchers suspect that pyrethrins and pyrethroids may alter brain development, leading to learning disabilities and other problems. During one study, rats exposed to low doses of pyrethroids and an additional chemical, such as DEET or even common allergy medicine, developed brain damage after two months, according to Mohamed Abou-Donia, a professor of pharmacology and cancer biology and neurobiology at Duke University Medical Center who conducted the research. The EPA already considers permethrin, a popular pyrethroid, “a likely carcinogen” through oral exposure, although the agency also says the benefits of pest control outweigh the potential health risks.

Pyrethroids, the synthetic form of pyrethrins, were developed because they do not break down as quickly as the chrysanthemum-derived pyrethrins, and they do not require manufacturers to depend on the weather and political stability of African countries, such as Rwanda, where much of the commercial chrysanthemum crop is grown.

Elated to see organophosphates absent from store shelves, health experts have spent little time worrying about pyrethrins and pyrethroids. In high doses, organophosphates such as chlorpyrifos (marketed under the name Dursban) and diazinon — both of which can no longer be sold for residential use — may cause difficulty breathing, paralysis, seizures, loss of consciousness, coma, and death, according to the Centers for Disease Control and Prevention.

Dursban and diazinon, however, were targeted for phase-out by the EPA primarily because of their links to developmental disorders, according to Jason R. Richardson, an assistant professor of environmental and occupational medicine at Rutgers University. Mindful of the brain-damaging properties of organophosphates, Richardson began studying the effects of the neurotoxin that replaced them: pyrethroids. Although his work is not complete, he stated that children generally do not metabolize toxic chemicals as well as adults, and that ingested neurotoxins may lead to problems such as learning disorders.

“Our concern, as with all pesticides, is: Are we altering proper brain development, and can that lead to problems later on in life?” Richardson said.

The shampoo used on toddler Amber McKeown was made by Qualis Inc. of Des Moines, Iowa, and contained pyrethrin. Amber’s parents brought a wrongful death suit against Qualis and four retailers and distributors in 2002, claiming the child died even though they followed the instructions on the label. The case was settled for an undisclosed amount last year. Amber’s parents declined, through their lawyer, to comment for this article.

Qualis, which manufactured Osco Lice Treatment Shampoo, did not report Amber’s death to either the FDA or the EPA, according to agency representatives. (At the time, Qualis was not required to report the incident to the FDA; today, it would be).

Bob Perlis, the EPA’s assistant general counsel for pesticides, said it is unclear whether Qualis violated his agency’s reporting rules. Although head-lice shampoo is regulated by the FDA, Perlis said, the manufacturer of such a product still would have to report a death to the EPA if the company was made aware of the incident — through a lawsuit, for example — and if the active ingredient was used in a pesticide regulated by the EPA. Qualis had pyrethrin-based pesticides registered with the agency at the time of Amber’s death and still does, records show.

“I can’t say whether we’re pursuing a reporting violation, but we are looking at the facts of the case,” Perlis said.

Roxi Downing, who, according to EPA documents, is co-owner of Qualis, said the company would not comment on Amber’s death or on the safety of pyrethrins and pyrethroids.

A Healthy Dynamic?

Despite manufacturers’ assurances of safety, scientists have begun to pay closer attention to the effects of pyrethrins and pyrethroids on children. A team of researchers from Emory University’s Rollins School of Public Health and the CDC published a study in 2006 that found even children fed an exclusively organic diet had pyrethroid metabolites in their systems after their parents had used pyrethroid pesticides in their homes. Children tend to absorb and ingest more chemicals than adults because they frequently put their hands and other objects in their mouths and play on carpets or other treated surfaces, said Chensheng “Alex” Lu, an assistant professor of environmental exposure biology at Rollins.

“The acute toxicity for pyrethroids is not well defined, so [users] think it’s safer,” Lu said. “The problem with this assumption is that it leads to excessive use, and that’s not something I would ever recommend.” Pyrethroids, in his view, should be applied in homes only by professionals.

Dr. James Roberts, an associate professor of pediatrics at the Medical University of South Carolina who is studying the developmental effects of pyrethroids, agrees. “If you saw some roaches and you pick up a can of pyrethroid — especially if you really don’t like roaches, like my wife — you’re probably going to just go to town, and that’s far more than would be applied with a professional applicator,” Roberts said. “I can see the argument that pyrethroids are less acutely toxic than organophosphates, but no one’s convinced me yet that the pyrethroids don’t have any long-term neurotoxicity.”

Industry spokesman Osimitz, however, argued that “if you use something in a home and it’s there at some level greater than zero, someone’s going to get an exposure greater than zero. But there’s a lot of exposures that probably are trivial and don’t mean anything, like there are exposures to all kinds of naturally occurring chemicals in the foods we eat.”

Given the growing use of pyrethrins and, especially, pyrethroids, some fear that the EPA — as it did with organophosphates — will allow the chemicals to stay on the market even if evidence of harm becomes overwhelming.

“That’s been the story of pesticide use in the U.S. since World War II,” said Caroline Cox, research director for the Center for Environmental Health, an Oakland, California-based nonprofit that advocates for reduction of chemical usage. “Products are used for a long time, and then the problems, which we hadn’t thought about before, become obvious, and then we grapple with them. I have to ask the question: How many years will it take the EPA to realize there’s a problem with these chemicals?”

“I think really what we have is a pretty good balance,” responded Osimitz, who tells his clients not to worry. “If you don’t like what the agency is doing,” he says, “let’s get the data and let’s address it that way — no guarantee how the data is going to come out. I think that’s a healthy dynamic.”

Whether a healthy dynamic or not, the new data promise to rekindle a sharp debate over the safety of modern pesticide use. Stronger warning labels, tighter regulation and more thorough testing may well be in the future of these “safer” insecticides. The EPA, for its part, promises to consider all of these measures after the agency reviews its now-public database on pesticide incidents.

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