Pesticides and Children

Scientifically speaking, whether a link exists between pesticides and childhood cancer is still open to conjecture, and requires further study. Journalistically speaking, on the other hand, it almost appears as if it's a done deal.

Let's play word association. What images do these words conjure? Pesticides. Cancer. Children. Illness. Chemical sensitivity. The media.

For anyone who's been associated with the structural pest control industry for more than a couple of years, these words, taken as a group, almost certainly invoke a range of emotions and physical responses, none of them pleasant: nervousness, sweaty palms, cold chills down the spine, anger. Perhaps above all, fear.

But for pest control professionals, these words generate a different kind of fear than they might for the average American. Not a fear of the unknown, not a fear that something you can't see may somehow get inside you and make you sick. No, this is the kind of fear that leads a PCO to believe the public may turn against him, may suddenly decide he's doing them more harm than good and they don't want or need his services anymore. It's the fear, essentially, of waking up one day to find you've become obsolete.

It may be a matter of perception, or it may be fact, but whatever it is, it certainly seems that the number of media "attacks" unflattering reports based on sketchy information, journalistic conjecture, innuendo against the structural pest control industry has been multiplying of late. For a small taste of this, refer to "House Guests From Hell," PCT, November 1994, page 24; and "CBS's Eye To Eye Alleges Illnesses Caused By Dursban," PCT, February 1995, p. 20.

The latest attack was one that turned up in USA Today, "The Nation's Newspaper," on February 27. Home Pesticides Linked To Some Cancer In Kids blared the Page 1 headline. The first sentence was just as damning , if not more so: "Lawn treatments and home pest extermination are associated with an increased risk of cancer in children, says a study in the current American Journal of Public Health."

The study in question was performed last year by two researchers at the University of North Carolina, Jack Leiss and David Savitz. In the USA Today article, re-porter Anita Manning briefly described the parameters of the UNC study. (In brief: 474 families in the Denver, Colo. area were surveyed; 252 of the families had children who were diagnosed with cancer between 1976 and 1983; the other 222, which were control subjects, had similar demographic characteristics but no instances of cancer. The survey questions, of which there were only three, are detailed later in this article.) Manning went on to report three major conclusions of the study:

• Children whose yards were treated with chemicals were found to be four times as likely to be diagnosed later with soft-tissue sarcomas, which are malignant tumors of muscle and connective tissue. "Researchers did not ask what chemicals were used, but say those `most likely to be used by people in the study area' were 2,4-D, carbaryl and Diazinon," Manning wrote.

• Children whose homes contained pest strips faced 2½ to 3 times the risk of leukemia. "The resin strips used to kill flies are treated with dichlorvos," Manning reported. "Den nis Utterback of the EPA says dichlorvos is undergoing review because `of concerns about the risks of cancer and neurotoxicity.'"

• Children whose homes had been exterminated for fleas, termites or other insects faced a slightly elevated risk of lymph cancer. The most likely chemical "culprits" here, according to the USA Today report, are chlordane, heptachlor, Diazinon and chlorpyrifos (Dursban).

CREDIBILITY AT ISSUE. In response to the story, several pest control-related trade associations including the National Pest Control Association, the Professional Lawn Care Association of America, and RISE (Responsible Industry for a Sound Environment) issued news releases refuting the allegations made in the USA Today article and pointing out several errors that were made in the story.

The responses of leading professionals in the pest control industry and related industries raised issues of credibility both with the USA Today report and with the original University of North Carolina study, which was published in the February 1995 issue of the American Journal of Public Health (AJPH).

The USA Today report, for instance, makes claims that go well beyond what is stated in the study itself. In addition to the headline, which is plainly misleading and inflammatory, the report's lead sentence, as quoted earlier in this story, asserts that the study conclusively proves that "lawn treatments and home pest extermination are associated with an increased risk of can-cer in children." (Emphasis ours.)

The simple truth is that the study as published in AJPH is for the most part in-conclusive, and makes nowhere near such a definitive statement as that asserted in the USA Today report. The AJPH study, in fact, concludes as follows: "Two major conclusions can be drawn from this study. First, some types of home pesticide use MAY BE associated with some types of childhood cancer. Second, more study is needed to clarify which specific exposures, if any, are associated with which particular childhood cancers." (Emphasis ours.) In this case, the difference between USA Today's "are associated with" and AJPH's "may be associated with" are as wide as the mouth of the Grand Canyon and also as treacherous.

"The USA Today article obviously went well beyond what the study itself stated," Richard Kramer, director of research, training and technical resources for the NPCA, told PCT in a recent interview. "It distorted the facts a great deal."

Kramer, an outspoken critic of current journalistic practices, said this latest circumstance bolsters his beliefs about the media. "My personal opinion of journalism today is that they'll grab at anything that they feel they can sensationalize so they can increase their readership," he said. "Today, even some of the so-called `respected' newspapers sometimes seem to be following in the National Enquirer's footsteps. They may not be that bad yet, but they're headed in that direction."

Newspapers, Kramer said, have a duty to be more responsible to their readers than USA Today was in this case. "They ought to have a person who has a good, solid understanding of science reviewing articles like this before they're published," he suggested. "There are an awful lot of people out there who believe a great deal if not all of what they see and read in the media. And none of them have a copy of the original study in front of them that they can refer to. So they have to rely on newspapers like USA Today to give an accurate representation of what they're covering. It's very unfortunate when something like this finds its way into print. It misleads a huge number of people."

NO ENDORSEMENT. PCT called Jack Leiss of the State Center for Health and Envi ronmental Statistics in Raleigh, N.C., who led the UNC study, to ask whether he believed USA Today's interpretation of his study was fair and accurate. Leiss, interestingly, declined to endorse the article. "I can only really comment on our work on the contents of the study itself," Leiss said. "I can't take responsibility for what the media did with this study, or with how they reported it."

NPCA's Kramer also took issue with the publication of the names of specific pesticides that may or may not have been used in the homes of the individuals queried in the study. The naming of those pesticides was based purely on conjecture; in the AJPH study, Leiss and company simply named some pesticides that were widely used during the time period that the study covered (1976 to 1983) for the types of treatments delineated in the study.

Of the three pesticide use categories set forth in the study, the one of most import to pest control professionals, obviously, is home exterminations. (Although there is some PCO crossover, yard treatments pertain primarily to a separate industry; and pest strips are for the most part a relic of the past as far as the pest control industry is concerned.) Significantly, in the home exterminations category, the study found the weakest correlations overall between pesticide use and childhood cancer.

In the home exterminations category, the pesticides chlordane, heptachlor, diazinon and chlorpyrifos were implicated, both by the study's authors and by the USA Today reporter. Leiss and Savitz had no evidence that those chemicals were used in any of the homes surveyed in their study. In the AJPH article, the authors simply state that those four pesticides were the most likely ones to have been used for home exterminations during the study period. No questions about specific pesticides were asked in the survey; it's highly unlikely the respondents would have been able to recall if they ever knew at all what pesticides were being used in their homes.

"No, we didn't ask (the people surveyed) what specific chemicals were used," Leiss said. "It would be useful for future research to try to obtain that type of information."

According to NPCA's Richard Kramer, speculating that chlordane and heptachlor were the most likely chemicals used in those treatments is highly debatable and irresponsible. "Those products weren't even registered for any types of actual inside-the-home treatments during that period," Kramer said. "Chlordane was registered, but only for termite treatments in the soil. I think that was an example of throwing in a word just for the sensationalism of it. People can identify with the word chlordane, but not necessarily with chlorpyrifos, because chlorpyrifos hasn't received anywhere near the amount of negative publicity that chlordane has received. It's a word people can remember and identify with, so that's why they tossed it in there, in my opinion."

CRUDENESS & BIAS. Leiss admitted there were a couple weaknesses in his study the "crudeness of the exposed measures" and the potential for "recall bias." Of the first, he explained that "crudeness" is simply a scientific term related to the general (in other words, undetailed and nonspecific) nature of the questions posed to the parents in the survey. Those questions were:

• Whether their residence "was ever exterminated for insects or pests so that they had to leave the house for a few hours." (Note that nowhere were specific pests such as termites and fleas mentioned in the AJPH study, although they were in the USA Today article. This is another apparent case of the USA Today reporter jumping to conclusions based purely on speculation.)

• Whether the yard surrounding the residence "was ever treated with insecticides or herbicides to control insects or weeds."

• Whether they ever used "hanging pest strips for insect control in the home."

"We asked people three very general questions," Leiss told PCT. "They weren't specific, they weren't detailed. From a scientific perspective, it is more difficult to establish a link when crude measures are used."

Because of this, he said, "future studies should be aimed toward collecting more specific measures of exposure in terms of age, duration, intensity, and particular chemical agents. The direction I think this research has to move toward is documented exposure data. That is, relying on written records of pesticide use. Because it's difficult for people to know or remember the details of the pesticides used."

The most efficient way to obtain documented exposure data, Leiss said, would be through "the cooperation of the pest control professionals who are applying the pesticides."

Of the second potential weakness of the study, Leiss explained, "When you're dealing with people's memories of past events, it opens you up to what is known as `recall bias.' For instance, parents of people who've been diagnosed with cancer might be more prone to remember or report instances of pesticide use in their homes than those who had no cancer in their family. Any specific study that relies on people's memories has the possibilities of being open to recall bias."

Leiss said he believed his study wasn't subject to significant recall bias because of "the heterogeneous nature of the effects across different exposures and cancer types that we found. If you look at the results in the table, the elevated odds ratios are scattered out among different types of cancers and different types of (pesticide) treatments." If recall bias were present, he said, there likely would have been a more clearcut pattern evident in the data.

SUMMING IT UP. Asked what he feels is the major "take-home" point of his study, Leiss summarized thusly: "This study does not constitute proof that home pesticide use causes cancer in children. It does, however, raise some serious concerns--especially when taken together with some of the earlier studies done in this area--that some types of home pesticide use may be associated with some types of childhood cancer."

Those "somes" and "maybes" provide a lot of room for uncertainty, a lot of space for the final proof--the truth, as it were--regarding this pesticide-childhood cancer "link" to roam around in. One thing those "somes" and "maybes" ("Waffle words," the White House press corps would call them) don't provide, on the other hand, is "hot copy"--in other words, the makings of an interesting news article. That, we can assume, is why USA Today buried them in the "fine print" toward the end of their article--at a point that many readers' eyes would never make it down to. Most readers, in fact, might never even make it beyond the headline or the first or second paragraph.

That, apparently, is how the journalism game is being played in the in the U.S. today (even among some of the "respected" news organizations), especially as it relates to hot-button "scare campaign" issues such as the "link" between pesticides and cancer. Perhaps we're drawing perilously close to the time where we'll have to amend the old "Don't believe everything you read in the papers (or hear on TV)" bromide; maybe it's almost time to change that every to any. Certainly we can hope otherwise. But if you're lucky, that hope and a dollar will buy you a cup of coffee.

The following is excerpted from a media analysis compiled by National Pest Control Association communications director Joel Paul in response to the article "Home Pesticides Linked To Some Cancer In Kids," published in USA Today's February 27 issue on page 1.

This study clearly failed to correlate specific products, concentrations, frequency of use, and the acute toxicity and chronic toxicity in determining the risks of exposure and the incidences of cancer reported in this study.

One of the study's authors, Jack Leiss, formerly with the Department of Biostatistics and Carolina Population Center at the University of North Carolina, emphasized that the study doesn't prove a connection to any chemicals. It didn't measure specific exposures and relied on parents' faulty memories. "We found within our data that there's a strong indication that some home use of pesticides is associated with some childhood cancers," Leiss is quoted as saying. But he also cautions that "it's only a suggestion because of the limitations of our study. You cannot infer cause and effect at all. Further research needs to be done to elucidate that."

Dr. Clark Heath of the American Cancer Society urged that better research needs to be done, and that "people shouldn't draw conclusions from this study." The study is similar to a handful of others that have suggested possible links between pesticides and cancer, but nothing is conclusive, Heath said in his article.

Publishing excerpts from a study that is inconclusive spreads misleading and inflammatory information to an already anxious and confused public, especially when the article itself warns parents that they shouldn't overreact to this study. However, we know that any disclaimer cannot balance the negative effect of a headline that declares "Home Pesticides Linked To Some Cancer In Kids."

Pete Fehrenbach is Editor of PCT magazine.