Morphological, biochemical, and histopathological indices and contaminant burdens of cotton rats (Sigmodon hispidus) at three hazardous waste sites near Houston, Texas, USA.

Male cotton rats (Sigmodon hispidus) were studied at three industrial waste sites near Houston, Texas, to determine whether various morphological, biochemical, and histopathological indices provided evidence of contaminant exposure and toxic insult. Only modest changes were detected in cotton rats residing at waste sites compared with reference sites. No single parameter was consistently altered, except hepatic cytochrome P-450 concentration which was lower ( [Formula: see text] ) at two waste sites, and tended to be lower ( [Formula: see text] ) at a third waste site. Elevated petroleum hydrocarbon concentrations were detected in rats at one waste site, but contaminant burdens of rats from the other sites were unremarkable. Unlike rats captured in summer, those trapped in winter exhibited hepatocellular hypertrophy and up to a 65% increase in liver: body weight ratio, cytochrome P-450 concentration, and activities of aniline hydroxylase, aryl hydrocarbon hydroxylase, and glutathione S-transferase. Although genotoxicity has been previously documented in cotton rats residing at two of the waste sites, biomarkers in the present study provided little evidence of exposure and damage.

Poisoning of Canada geese in Texas by parathion sprayed for control of Russian wheat aphid.

Approximately 200 Canada geese (Branta canadensis) died at a playa lake in the Texas Panhandle shortly after a winter wheat field in the basin adjacent to the lake was treated with parathion to control newly invading Russian wheat aphids (Diuraphis noxia). No evidence of infectious disease was diagnosed during necropsies of geese. Brain ChE activities were depressed up to 77% below normal. Parathion residues in GI tract contents of geese ranged from 4 to 34 ppm. Based on this evidence, parathion was responsible for the goose mortalities. Parathion applications to winter wheat will undoubtedly increase if parathion is applied for control of both Russian wheat aphids and greenbugs (Schizaphis graminum). Geese may potentially be exposed to widespread applications of parathion from fall to spring, essentially their entire wintering period.

Isolation of poxvirus from debilitating cutaneous lesions on four immature grackles (Quiscalus sp.).

Poxvirus was isolated from nodules on four immature grackles (Quiscalus sp.) collected in two residential areas of Victoria, Texas. All of the birds were emaciated and had nodules on the eyelids, bill, legs, toes, and areas of the skin on the wings, neck, and ventral abdomen. These pox nodules were extensive and probably interfered with both sight and flight. The preliminary diagnosis was confirmed by virus isolation, histopathology, and electron microscopy. Poxvirus was isolated on the chorioallantoic membrane of embryonated hen's eggs and in Muscovy duck embryo fibroblast cell culture. Phaenicia calliphoridae (blowfly) larvae were found in one of the pox nodules, raising the possibility of mechanical transmission of the virus by contaminated adult blowflies.

Small mammal populations at hazardous waste disposal sites near Houston, Texas, USA.

Small mammals were trapped, tagged and recaptured in 0.45 ha plots at six hazardous industrial waste disposal sites to determine if populations, body mass and age structures were different from paired control site plots. Low numbers of six species of small mammals were captured on industrial waste sites or control sites. Only populations of hispid cotton rats at industrial waste sites and control sites were large enough for comparisons. Overall population numbers, age structure, and body mass of adult male and female cotton rats were similar at industrial waste sites and control sites. Populations of small mammals (particularly hispid cotton rats) may not suffice as indicators of environments with hazardous industrial waste contamination.

Monocrotophos and dicrotophos residues in birds as a result of misuse of organophosphates in Matagorda County, Texas.

About 1100 birds of 12 species died from organophosphate poisoning in Matagorda County on the Texas Gulf Coast in March and May 1982. Birds died from feeding on rice seed that was illegally treated with dicrotophos or monocrotophos and placed near rice fields as bait to attract and kill birds. Brain acetylcholinesterase inhibition of affected birds averaged 87% (range 82-89%), and contents of gastrointestinal tracts contained residues of dicrotophos (5.6-14 ppm) or monocrotophos (2.1-13 ppm). Rice seed collected at mortality sites contained 210 ppm dicrotophos or 950 ppm monocrotophos. Mortality from dicrotophos poisoning continued for almost 3 weeks. The practice of illegally treating rice seed with either of these 2 organophosphates appears to be infrequent but widespread at present.