Pesticides and Wildlife - ACS Publications - American Chemical Society

Chapter 25

Hurdles in Compiling Pesticide Incidents

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Patrick J . Hannan NOWCC/Senior Environmental Employee Program, Mail Code 7507C, U.S. Environmental Protection Agency, Ariel Rios Building, Washington, DC 20460

Pesticides must be registered by the United States Environmental Protection Agency (EPA) before they can be offered for sale. They also must be re-registered periodically. A factor to be considered in the re-registration is the number of recorded incidents in which they have been shown to be hazardous to humans, to wildlife, or to the environment. This paper discusses the Ecological Incident Information System that is concerned primarily with the damaging effects of pesticides on plants and wildlife, primarily fish and birds. Included is an account of how EPA is made aware of pesticide incidents, and how the information obtained is used to classify the degree of blame assigned to a pesticide. This particular database does not include human exposure incidents which are within the scope of another reporting system.

Being Made Aware The principal hurdle in compiling incidents is learning that they exist. EPA must depend on the voluntary contributions of State environmental or agriculture offices, its own regional offices, and interested citizens who report bird kills, fish kills, and crop damage that have been caused by pesticides. Many incidents are reported by pesticide manufacturers (under 6(a)2 requirements) who inform EPA of any complaints they have received regarding their products. Recent changes in the reporting requirements have lowered the threshold of such reportings; whereas one or two initial incidents may have been needed to justify disclosure previously, now even allegations are a sufficient justification. On the other hand, under the new guidelines a registrant might provide less information on a given incident than had been required before. Prominent among the 6(a)2 reportings are instances in which lawns are damaged, or field crops diminished, by herbicides that have either run off of treated areas, or have drifted during crop spraying. Of course, there have been substantial fish kills resultingfromthe contamination of creeks or ponds by the runoff of pesticides that U.S. government work. Published 2001 American Chemical Society In Pesticides and Wildlife; Johnston, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 2000.

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360 have been applied in a manner consistent with their registration limits but, afterwards, are washed away by substantial rains. Even if an interested citizen becomes aware of an environmental problem caused by pesticide usage, there often is a substantial delay before an incident reaches the database. The uninformed public faces information barriers in reporting any incident. What phone number should be called? Whose task is it to investigate? Even if one calls the correct number and receives an automated impersonal response, will he have the patience necessary to complete the call? It is certain that only afractionof the incidents caused by pesticides reach EPA's attention, simply because people do not know how to report them.

Once the News Has Reached EPA

Certainty Discussion For every incident reported to the EPA, a judgment must be made concerning its cause. Toward this end the database includes options ranging from "Unlikely" to "Highly Probable." Of primary importance in entering an incident is the matter of certainty. For a pesticide to be judged the "Highly Probable" cause of an incident there must be convincing evidence that it was, indeed, the cause. Generally this must include an analysis of the carcass showing the presence of the suspected pesticide at a substantial concentration. Additional evidence might be an effect on an organ that is known to be affected by the pesticide. For example, an organophosphate may have been detected in the esophagus contents of a bird, and the bird's cholinesterase activity may have been far below normal; in such a case, the "Highly Probable" classification would be appropriate. For the term " Probable" to be applied, the evidence would be less convincing. Perhaps the cholinesterase activity was measured and found to be below normal, and it was known that an adjacent field was sprayed with a pesticide having anti-cholinesterase activity. Such a combination of factors would warrant the judgment that this pesticide was probably responsible for the incident. In many cases the term "Possible" is the only alternative in judging whether a given pesticide is responsible for an incident. Suppose multiple analyses are performed on the carcass of a bird, showing a variety of DDT metabolites and several highly toxic compounds at very low concentrations; it could be that there was a combined influence of all of those components and the only reasonable approach would be to classify each as a possible cause of death. Also, as mentioned above, another large source in the "Possible" category is the plethora of incidents reported by pesticide manufacturers under the 6(a)2 requirements imposed by EPA. Typically, a citizen complains that a product was used to kill the weeds in his lawn and the whole lawn was affected. The

In Pesticides and Wildlife; Johnston, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 2000.


361 manufacturer reports that such a complaint was made but supplies no other information - and might not have any. In the absence of any analytical information, it can only be concluded that the pesticide in question was a possible cause. The term "Unrelated" is another potential tag to apply to the relationship between a pesticide and an environmental incident. No further explanation for that should be required for this forum. It is pertinent here to add a note about the significance of cholinesterase activity levels. Carbamates, for example, will severely inhibit cholinesterase activity but a partial recovery from their effect is possible with the passage of time. Organophosphates, on the other hand, have an irreversible effect on cholinesterase activity. An intermediate cholinesterase activity might result from a situation in which the brain has recovered partiallyfromthe presence of a carbamate. Another possibility is that the sample being analyzed included tissue that was extraneous to the brain.

Use/Misuse Variations It would be unjust to blame a pesticide for an incident if it has been used in a way that is not permitted according to the label. Suppose someone is sufficiently exasperated with bird droppings on his car that he laces a slice of bread with Pesticide X and leaves it in an area where it would attract birds. That is clearly a misuse of the pesticide and the resultant bird kill should be in the misuse category. Generally, misuses of this type are easily identified. In recent years there have been many such instances in New York City and, while the perpetrator may not have been discovered, there is no doubt about the source of the lethal dose. There are many other instances in which the aerial application of a pesticide has caused severe contamination of ponds, the result being many dead fish. Often such an occurrence is judged to be a misuse of the offending pesticide. In all of these cases, however, the person making the entry into the database must depend on the accuracy of the account forming the basis of the case.

Dissolved Oxygen vs Pesticide Fish present a unique case in that they must depend on sufficient oxygen in their waters to sustain life. If a substantial number of fish have died in a pond, was the cause a lack of dissolved oxygen (D.O.) or was it the presence of a pesticide? In many instances the cause is clear cut, such as a heavy rain storm immediately following the application of chlorpyrifos to the foundation of a new home nearby. But there are many instances in which there has been a trace concentration of a pesticide in a water body


362 having a marginal dissolved oxygen concentration. If the investigator has determined the D.O. content, that is an obvious help. Still, it is probable that the D.O. sample was taken in daylight hours when the reading may be considerably higher than if it had been taken at 2:00 A M . That is one complication. Another is that some fish cope with a low D.O. concentration far better than others.


Time of sampling In conjunction with the D.O. problem is the matter of how and when a sample was taken. Let us suppose that there has been a fish kill and a subsequent analysis of the water, showing less than a part-per-billion of a pesticide that might be suspected as the source of the problem. Was the pesticide responsible? That might be hard to determine unless information related to the sampling is available. If the sample is taken within hours of the apparent fish kill, perhaps the concentration found is representative of the conditions pertaining to the kill. But suppose the sample is taken a week after the incident was noticed - - what does it mean? It might not mean anything, and the judgment of the one entering the incident into the database must depend on an evaluation of what is known. A problem often encountered, however, is that the time the sample was taken is not known. Each reporting agency has its own form - - if, in fact, it uses a form rather than a simple narrative account. It is common to encounter forms which mention the date of the report being made, and the date of the incident, but with no mention of the time a sample was taken. Then, too, there is the problem of the adsorption of trace amounts of a pesticide to the walls of a sampling vessel, causing the analysis to reflect a concentration considerably lower than it had been. That is a matter too complicated for a complete discussion in this short report.

Talents of the Investigator With the difficulties cited above in the collection of data surrounding a pesticide incident, it is clear that a weak link in the chain can be the background of the one making the investigation. In the case of a fish or bird kill, the most important evidence would be the carcass of a victim; if a substantial concentration of a pesticide is found, then the decision becomes automatic. It is obvious, however, that reports are often submitted by personnel having insufficient training. They might be knowledgeable regarding fish classifications, for example, but have no knowledge of chemistry. Rather than collect a carcass, freeze it, and make arrangements to have it analyzed, they might be content to take a water sample even though it would be days after the incident has taken place. It is a fact, too, that a number of investigations are carried out by people who


363 are not trained. In today's world, where spelling seems to be a lost art, it would be risky to assume that several misspelled words in a report would reduce its credibility. But when phrases such as " - - the bream was intoxication," or " - - he had did everything possible" are present, there is some doubt about the capability of the investigator.


An Interesting Disconnect EPA maintains a large Pesticide Ecotoxicity Database in which summaries of pesticide toxicities toward plants, fish, and birds can be found. This is valuable in making judgments about which pesticide, among several identified in a carcass, may have been responsible for the death of the subject. Upon reflection, however, one is aware of an inadequacy in the process of assigning a cause for an environmental incident. The Pesticide Ecotoxicity Database provides one measure, namely the concentration required to kill something. But that does not match up with what the compiler of the incident database has to work with, viz the concentration of pesticide X in a fish or bird. If there were tabular data relating the concentration of a compound in a fish, to that in the water in which it was swimming, it would be useful. Of course, the situation in the real world is much more complex. There may have been a large pulse of pesticide input to the water followed by rapid dilution, which would produce results that are radically differentfroma chronic situation in which a considerably lower concentration in the water would have prevailed for an extended period. I discussed the matter with Dr. Emmett Braselton, Chief of the Toxicology Unit at Michigan State University and he told of two examples he often relates to his students: Case #1 : A liver specimen from an animal was received for study. A previous study showed that the brain cholinesterase activity was normal, so one would tend to rule out an organophosphate as the cause of death. However, they found a high concentration of malathion (an organophosphate) in the liver. This was a case of acute poisoning in which the animal had died before the organophosphate reached the brain. Case #2: A liver specimen was analyzed by GCMS and no organophosphates were found. But the brain cholinesterase activity was reduced. So then they ground up the brain and extracted it, and found that it contained malathion. This was considered a case of chronic poisoning that had occurred over time and, even though there was no malathion detectable in the liver, it had been exerting its effect on the brain.

OVERALL SUMMARY In writing this report it has been necessary to point out the limitations of an incident database related to pesticides. There are many problems associated with making



364 judgments on an environmental situation when one is far removed from it. On the other hand, such an instrument is necessary and useful despite its inherent limitations. Pesticides by their nature are toxic to a certain segment of the earth's biota. If the dangers associated with them outweigh their benefits, they should be removed from the market. A pesticide incident database can shed light on those compounds that pose more risks than are warranted. It is in everyone ' s interest that the incident database be as complete and accurate as possible. Toward this end the active support of local and State agencies is required, and a greater emphasis on selecting personnel with technical backgrounds to investigate the causes is necessary. For those who have knowledge of an incident related to pesticides, they are asked to send the information to : Document Processing Desk Office of Pesticide Programs - - 7504C U.S. Environmental Protection Agency 401 M St. S.W. Washington D.C. 20460 Another option would be to FAX it to EUS (Ecological Incident Information System) at 703-305-6309.


Pesticides and Wildlife - ACS Publications - American Chemical Society

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