From the U.S. Geological Survey, Patuxent Wildlife Research Center -- 'Critique on the Use of the Standardized Avian Acute Oral Toxicity Test for First Generation Anticoagulant Rodenticides' "First generation anticoagulant rodenticides (FGARs) generally require multiple feedings over several days to achieve a threshold concentration in tissue and cause adverse effects. This exposure regimen is much different than that used in the standardized acute oral toxicity test methodology." "Median lethal dose values derived from standardized acute oral toxicity tests underestimate the environmental hazard and risk of FGARs." "The exposure scenarios and stressors in the field can increase a bird’s sensitivity to a pesticide and therefore environmental exposures need not be as high as the dosages used in a laboratory study to elicit an effect (Vyas et al. 2006)." "Exposure regimens and doses that do not take into account the exposure scenario and time course of response of FGARs in the field further remove the relevancy of laboratory results to free-ranging birds." "Acute oral toxicity testing revealed that diphacinone is about 20 times more toxic to American kestrels than to Northern bobwhites (LD50s = 96.8 mg a.i./kg and 2014 mg a.i./kg, respectively) (Rattner et al. 2010, 2011a). This comparative testing does identify a more sensitive species." "The inappropriateness of the standardized acute oral toxicity test for FGARs has also been addressed for mammals." "Birds and mammals are more sensitive to FGARs in toxicity tests that provide low level exposures over several days than in the standardized acute oral toxicity test." "Since the standardized avian acute oral toxicity test is designed to elicit a response from a single-dose or divided multi- ple doses within 24 h, and since FGARs generally require small doses over several days, the results of standardized avian acute oral toxicity tests using FGARs do not seem to be valid indices for evaluating toxicity among the three rodenticide classes." "The FGARs, therefore, artificially appear less toxic than they are and may not trigger the levels of concern for identifying risk (Primus et al. 2001; USEPA 2004; Eisemann and Swift 2006). Consequently, the hazards and risks previously reported may be underestimated." "Caution is also warranted when using the findings of standardized acute oral toxicity tests to assist in the diagnosis of the cause of death of an animal collected from the field. Some of the physiological responses produced by the disproportionately large exposure levels in the standardized acute oral toxicity testing may not be consistent with typical signs of FGAR poisonings seen in wild birds (Smith 1998)." "Therefore, FGAR residue values in tissues derived from acute oral toxicity test may not be suitable benchmarks for confirming FGARs as the cause of death in wildlife and for predicting the risk of secondary poisoning." "There are many inherent differences between laboratory populations and wild birds. Free-ranging birds contend with the chemical interactions, multiple exposures, nutrition, health, injuries, and other stressors that, however, are of less concern for captive birds. The exposure scenarios and stressors in the field can increase a bird’s sensitivity to a pesticide and therefore environmental exposures need not be as high as the dosages used in a laboratory study to elicit an effect (Vyas et al. 2006)." Exposure regimens and doses that do not take into account the exposure scenario and time course of response of FGARs in the field further remove the relevancy of laboratory results to free-ranging birds." "However, despite literature (as far back as 1986) documenting that the standardized acute oral toxicity test is not suited for FGARs, the USEPA, USGS, U.S. Fish and Wildlife Service, and the U.S. Department of Agriculture continue to conduct standardized acute oral toxicity testing for FGARs and continue to use the results in their risk characterizations, and for planning and operational rodenticide applications." "The FGARs’ mode of action, the continued use of standardized acute oral toxicity testing method, and the growing use of FGARs necessitate the development of a standardized avian low-dosage multiple-day toxicity testing methodology in order to correctly assess their hazards and risks." http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1970&context=usgsstaffpub To learn more about these helicopter poison drops in Hawaii, New Zealand and islands worldwide, please join us at 'It Takes a Village Kauai' on Facebook: https://m.facebook.com/groups/1884230138270651?tsid=0.7103491246256949&source=result