Our I.ivini; Rc\oiincs — Htimiin liithicines 



417 



follow-ups to specific pesticide applications. In 

 fact, there is often no suspicion of OP or carba- 

 mate pesticide poisoning because it is only after 

 necropsy and laboratory testing that the poison- 

 ing is revealed. A cholinesterase (ChE) screen- 

 ing test compares brain ChE activity (primarily 

 acetylcholinesterase activity) in a bird suspect- 

 ed of being poisoned with the ChE activity of 

 normal birds of the same species. Enzyme activ- 

 ity reduced HWr or more is considered evidence 

 of exposure to a cholinesterase-inhibiting com- 

 pound; a reduction greater than 50% is evidence 

 of lethal exposure (Ludke et al. 1975). In these 

 incidents the cholinesterase-inhibiting com- 

 pounds are OP and carbamate pesticides, and 

 specific OP and carbamate compounds may be 

 identified by chemical analysis of esophagus or 

 stomach contents. 



Effects on Wildlife 



Wildlife mortality attributed to OP and car- 

 bamate pesticides has been documented for at 

 least two decades, and the number of incidents 

 recorded since 1980 is increasing (Fig. 1). In 

 this article, 207 separate mortality incidents 

 related to an OP or carbamate pesticide are 

 described. These incidents occuiTed in nonen- 

 dangered wildlife from 1980 to 1993. Of the 

 207 mortalities, a specific chemical compound 

 was identified as the cause of death in 124 inci- 

 dents and 19 different compounds were detect- 

 ed. Of the specific compounds identified. 4 

 were carbamates and 15 were OP compounds 

 (Table). Carbamates were responsible in 31 

 mortalities while OP compounds were responsi- 

 ble in 93. On the basis of inhibited ChE activity 

 in the brain, carbamate and OP pesticides were 

 suspected as the cause of 64 additional inci- 

 dents. In 19 unconfirmed reports, 5 had 20%- 

 40% brain ChE inhibition, exposure levels not 

 considered high enough to be lethal. The 

 remaining 14 had a histoid suggesting pesticide 



Table. Specific compounds identified in organophospho- 

 rus and carbamate pesticide-related wildlife mortality inci- 

 dents, 1980-93. 



exposure, but a diagnostic evaluation was not 

 made. 



Thousands of birds representing more than 

 50 species including waterfowl, passerines, 

 colonial waterbirds. shorebirds. gulls, raptors, 

 and others have been killed in these incidents. A 

 die-off incident can involve a few birds of one 

 species or hundreds of birds of a variety of 

 species. Gross necropsy findings in birds dying 

 from OP and carbamate toxicity were minimal. 

 Lung edema and hyperemia (see glossary) were 

 the predominant findings when lesions were 

 ob.served. Mammals such as Virginia opossum 

 (Diclelphis virginiana), raccoon (Procyon 

 Idtor). and coyote {Canis hitnuis) were occa- 

 sionally involved. 



40- 



86 



Year 

 Fig. 1. Number of organophos- 

 pfiorus and carbamate pesticide- 

 relaled wildlife mortality inci- 

 dents. 1980-93. 



Fig. 2. Location by state of organophosphorus and carbamate compounds in pesticide-related 

 wildlife mortality incidents. 1980-93. 



The geographic distribution of mortality 

 associated with specific compounds varied, 

 although multiple incidents where the same 

 compound was identified occurred within states 

 (Fig. 2). Of the 124 deaths where a specific pes- 

 ticide was identified. 64 had a known pesticide 

 application (Fig. 3). The application varied 

 from use on agricultural crops or livestock 

 (agricultural) to lawn care or other uses in resi- 

 dential areas (residential) and on golf courses. 

 Other known applications did not fall into these 

 three categories and are primarily incidents of 

 intentional baiting with grain. 



Documentation of wildlife mortality in this 

 manner has supported restrictions on the use of 

 some OP and carbamate pesticides, such as the 

 removal of diazinon from use for turf applica- 

 tions and limiting the use of granular carbofu- 

 ran. Studies are under way to determine the sub- 

 lethal effects of these chemicals (Grue et al. 



Other 7% 

 Residential ^Innlf courses 

 11°o ---'""^^^^■-^ 2% 



.ij 



Agricultural 

 32% 



Unknown 

 48% 



Fig. 3. General type of applica- 

 tion associated with organophos- 

 phorus and carbamate pesticide- 

 related wildlife mortality inci- 

 dents. 1980-93. 



