Subchronic organophosphorus ester-induced delayed neurotoxicity in mallards

Pathophysiological Effects of Chronic Toxicity with Synthetic Pyrethroid, Organophosphate and Chlorinated Pesticides on Bone Health of Broiler Chicks

This experiment evaluated effects following chronic toxicity with 20 ppm fenvalerate (synthetic pyrethroid), 2 ppm monocrotophos (organophosphate) and 2 ppm endosulfan (chlorinated hydrocarbon) on bone health of broiler chicks. A total of 120 chicks were divided equally into 4 groups and were fed poultry mash without (control) or mixed with different pesticides for 8 weeks. Body mass, serum calcium and phosphorus levels were unaffected due to pesticides treatment. However, an increase ( p < 0 .01) in serum alkaline phosphatase activity was noted and serum total protein decreased ( p < 0 .01) in all treated groups. Roentogenography revealed destructive changes in the upper part of the femur in the monocrotophos group. Endosulfan intoxicated chicks had increased numbers of trabeculae in the medullary cavity. Microscopic alterations of the costochondral junction in intoxicated chicks were similar. The zones of proliferating, maturing and degenerating, and calcifying cartilage cells were reduced in width and the metaphysis in treated birds showed a reduced number of cartilage cells and thinner trabeculae. Due to toxicity, the capillary scaffolding of the degenerating cartilage cells was reduced and a larger number of transverse trabeculae could be seen in the metaphysis. Appositional bone growth studied by the tetracyclicline labeling technique indicated decreased active osteons.

Ranking terrestrial vertebrate species for utility in biomonitoring and vulnerability to environmental contaminants

The measurement of contaminant tissue concentrations or exposure-related effects in biota has been used extensively to monitor pollution and environmental health. Terrestrial vertebrates have historically been an important group of species in such evaluations, not only because many are excellent sentinels of environmental contamination, but also because they are valued natural resources in their own right that may be adversely affected by toxicant exposure. Selection of appropriate vertebrates for biomonitoring studies frequently relies on expert opinion, although a few rigorous schemes are in use for predicting vulnerability of birds to the adverse effects of petroleum crude oil. A Utility Index that ranks terrestrial vertebrate species as potential sentinels of contaminants in a region, and a Vulnerability Index that assesses the threat of specific groups of contaminants to these species, have been developed to assist decision makers in risk assessments of persistent organic pollutants, cholinesterase-inhibiting pesticides, petroleum crude oil, mercury, and lead shot. Twenty-five terrestrial vertebrate species commonly found in Atlantic Coast estuarine habitat (Rattner et al. 2001a) were ranked for their utility as biomonitors of contamination and their vulnerability to pollutants in this region. No single species, taxa, or class of vertebrates was found to be an ideal sentinel for all groups of contaminants. Although birds have overwhelmingly been used to monitor contaminants compared to other terrestrial vertebrate classes, the nonmigratory nature and dietary habits of the snapping turtle and mink consistently resulted in ranking these species as excellent sentinels as well. Vulnerability of Atlantic Coast populations of these species varied considerably among groups of contaminants. Usually a particular species was found to be at high risk to only one or two groups of contaminants, although a noteworthy exception is the bald eagle, which is highly vulnerable to all five of the contaminant groups examined. This index could be further enhanced by generation of additional comparative toxicity data to facilitate interspecific extrapolations. The Utility and Vulnerability Indices have application to many types of habitats in addition to estuaries and are of value to natural resource and risk managers that routinely conduct local, regional, or national environmental quality assessments.

Subchronic hepatotoxicity of selenomethionine ingestion in mallard ducks

Two-year-old male mallards (Anas platyrhynchos) received a control diet (0.2 ppm Se) or diets containing 1, 2, 4, 8, 16, or 32 ppm Se as selenomethionine for 14 wk. Se accumulated readily in the liver in a dose-dependent manner, reaching a mean concentration of 29 ppm (wet weight) in the 32 ppm group. Dietary Se of 2 ppm or greater increased plasma glutathione peroxidase activity. Mortality (10%) and histopathological effects, including bile duct hyperplasia and hemosiderin pigmentation of the liver and spleen, occurred in the 32 ppm group. These histopathological effects were accompanied by lower hemoglobin concentrations (16 and 32 ppm groups) and hematocrit (32 ppm group), and elevated plasma alkaline phosphatase activity (32 ppm group) indicative of cholestatic liver injury. Other manifestations of hepatotoxicity included significant linear dose responses for hepatic oxidized glutathione (GSSG) concentrations and ratio of GSSG to reduced glutathione (GSH). Means for both of these responses differed from controls in groups receiving 8-32 ppm Se. Mean hepatic GSH and malondialdehyde (a measure of lipid peroxidation) concentrations were significantly elevated in the 16 and 32 ppm groups. Subchronic effects of selenomethionine, which occurs in vegetation, are of particular interest with respect to the health of wild aquatic birds in seleniferous locations.