In preparation for a study of the relative oral bioavailability of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soils (typically containing less than 1 ppb 2,3,7,8-tetrachlo-rodibenzo-p-dioxin [TCDD] toxic equivalents [TEQ]), the background concentrations of PCDD/Fs and selected polychlorinated biphenyls (PCBs) were measured in liver and adipose tissue from female Sprague-Dawley rats and juvenile swine after 30 d of ingesting laboratory chow. The measured concentrations of TCDD and other PCDD/Fs in rat livers were severalfold less than previously reported in the literature for control (unexposed) laboratory rodents. The concentrations of PCDD/Fs and selected PCBs in livers of swine were three- to fourfold lower than those reported for rats. The lower concentrations found in this study compared to previous findings may be due to inadvertent laboratory contamination in previous studies or to declining levels of PCDD/Fs in laboratory feed, which parallel the declines in emissions, general environmental levels, and human food and tissue levels of PCDD/Fs.

The effect of the dosing vehicle (e.g., dough) on the ability of an in vitro gastrointestinal (IVG) method to predict relative bioavailable Pb associated with soil ingestion was evaluated. Bioaccessible Pb determined by the IVG method was compared with relative bioavailable Pb measured from dosing trials using juvenile swine for 18 contaminated soils ranging from 1270 to 14200 mg Pb kg(-1). Bioaccessible Pb was measured in the IVG gastric extraction (GE) and intestinal extraction (IE) solutions. Mean bioaccessible Pb values were 32.2% for GE without dough, 23.0% for GE with dough, 1.06% for IE without dough, and 0.56% for IE with dough. It is possible that phytic acid associated with the dough addition decreased bioaccessible Pb. In vivo relative bioavailable Pb ranges for different swine tissues were 1 to 87% for blood, 0 to 110% for liver, 1 to 124% for kidney, and 0.04 to 94% for bone. Strong linear relationships between IVG GE Pb with dough (r > 0.76, P < 0.0002), IVG IE Pb with dough (r > 0.56, P < 0.015), and IVG GE Pb without dough (r > 0.81, P < 0.0001) and in vivo bioavailable Pb as estimated with blood, kidney, liver, and bone were found. Inexpensive in vitro methods may be useful in providing an estimate of the variability in relative bioavailable Pb at a single study site. The IVG method can be used to estimate relative bioavailable Pb, As, and Cd in contaminated soil.

Soil ingestion by children is an important pathway in assessing public health risks associated with exposure to arsenic-contaminated soils. Soil chemical methods are available to extract various pools of soil arsenic, but their ability to measure bioavailable arsenic from soil ingestion is unknown. Arsenic extracted by five commonly used soil extractants was compared with bioavailable arsenic measured in vivo by immature swine (Sus scrofa) dosing trials. Fifteen contaminated soils that contained 233 to 17 500 mg kg(-1) arsenic were studied. Soil extractants were selected to dissolve surficially adsorbed and/or readily soluble arsenic (water, 1 M sodium acetate, 0.1 M Na2HPO4/0.1 M NaH2PO4) and arsenic in Fe and Mn oxide minerals (hydroxylamine hydrochloride, ammonium oxalate). The mean percent of total arsenic extracted was: ammonium oxalate (53.6%) > or = hydroxylamine hydrochloride (51.7%) > phosphate (10.5%), acetate (7.16%) > water (0.15%). The strongest relationship between arsenic determined by soil chemical extraction and in vivo bioavailable arsenic was found for hydroxylamine hydrochloride extractant (r = 0.88, significant at the 0.01 probability level). Comparison of the amount of arsenic extracted by soil methods with bioavailable arsenic showed the following trend: ammonium oxalate, hydroxylamine hydrochloride > in vivo > phosphate, acetate > water. The amount of arsenic dissolved in the stomach (potentially bioavailable) is between surficially adsorbed (extracted by phosphate or acetate) and surficially adsorbed + nonsurficial forms in Fe and Mn oxides (extracted by hydroxylamine hydrochloride or ammonium oxalate). Soil extraction methods that dissolve some of the amorphous Fe, such as hydroxylamine hydrochloride, can be designed to provide closer estimates of bioavailable arsenic.

Phosphate treatment of lead-contaminated soil may be a cost-effective remedial alternative for in situ stabilizing soil Pb and reducing Pb toxicology to human. The leaching behaviors of the P added to soil surface and the effect on subsurface Pb bioaccessibility must be addressed for this remedial technology to be acceptable. A smelter-contaminated soil containing an average of 2,670 mg Pb kg(-1), collected from the Jasper County Superfund Site located in Jasper County, Missouri, was surface treated with 10 g P kg(-1) as phosphoric acid (H3PO4). Following a simulated column leaching and 90-day treatment of field plots, respectively, bioaccessible Pb, P, and pH in soil profile were measured. Surface treatment using H3PO4 effectively stabilized soil Pb and reduced leach able Pb and the bioaccessibility. Phosphate leached into deeper profile significantly lowered bioaccessible Pb in subsurface. Reduction of Pb bioaccessibility increased as a linear function of increasing soil P. Although surface H3PO4 treatment resulted in an enhanced leaching of added P and may increase potential risk of surface and groundwater pollution, the P leaching under field conditions is very limited. Lime addition following the treatment may reduce the leachability of added P and further immobilize soil Pb.

Transformation of soil lead (Pb) to pyromorphite, a lead phosphate, may be a cost-effective remedial strategy for immobilizing soil Pb and reducing Pb bioavailability. Soil treatment using phosphoric acid (H3PO4) was assessed for its efficacy to reduce Pb solubility and bioaccessibility. Soil containing 4,360 mg of Pb kg(-1), collected from a smelter-contaminated site in Joplin, MO, was reacted with 1,250, 2,500, 5,000, and 10,000 mg of P kg(-1) as H3PO4. The reaction was followed by measurements of Pb bioaccessibility, solubility products, and microprobe analyses. Soluble Pb concentration in the soil decreased with increasing H3PO4 addition. Adding 10,000 mg of P kg(-1) reduced bioaccessible Pb by 60%. The logarithm of bioaccessible Pb decreased as a linear function of increasing H3PO4 addition with an R2 of 0.989. A higher soil/solution ratio was required to extract bioaccessible Pb after the treatment. Microprobe analyses showed that the Pb particles contained P and Cl after the reaction, and the spectra generated by the wavelength-dispersive spectrometer were similar to those of synthetic chloropyromorphite. Lead solubility in the P-treated soil was less than predicted for hydroxypyromorphite [Pbs(PO4)3-OH] and greater than predicted for chloropyromorphite [Pbs(PO4)3Cl]. The P treatment caused approximately 23% redistribution of soil Pb from the clay and silt size fractions to the sand fraction. Soil treatment with H3PO4 resulted in the formation of a compound similar to chloropyromorphite and reduced bioaccessibility of soil Pb, which may have a potential as an in situ technique for Pb-contaminated soil remediation.

OBJECTIVE:To determine the relationship between serum and liver copper concentrations and evaluate serum copper determination for diagnosis of copper deficiency in juvenile beef calves. DESIGN:Cross-sectional study. ANIMALS:105 juvenile beef calves. PROCEDURE:Copper concentrations were measured in paired liver and serum samples from 6- to 9-month-old beef calves. Regression models that predicted liver copper concentration as a function of serum copper concentration were developed. Sensitivity and specificity of serum copper concentration for detection of low liver copper concentration were determined, using a range of serum copper concentrations as test endpoints. Positive and negative predictive values were calculated. RESULTS:The association between serum and liver copper concentrations was significant; however, regression models accounted for only a small portion of the variation in liver copper concentrations. For a serum copper concentration endpoint of 0.45 microg/g, sensitivity and specificity for detection of low liver copper concentration were 0.53 and 0.89, respectively. Positive and negative predictive values of serum copper concentration for detection of low liver copper concentration ranged from 0.37 to 0.85 and 0.63 to 0.94, respectively. CONCLUSIONS AND CLINICAL RELEVANCE:Regression models are inappropriate for predicting copper status as a function of serum copper concentration. Serum copper concentration is fairly specific for detection of low liver copper concentration but only marginally sensitive when serum copper concentration of 0.45 microg/g is used as a test endpoint. The value of serum copper concentration as a diagnostic indicator depends on prevalence of copper deficiency.

Application of phosphoric acid (H3PO4) to lead (Pb)-contaminated soil may be a remedial strategy for in situ immobilization of soil Pb. Treatment homogeneity with three application methods was assessed by determining microscale pH variability through both conventional and spatial variance analyses. Soil containing an average 2570 mg Pb kg−1 near a smelter in Jasper County, Missouri, was treated with H3PO4 (10 g P kg−1) utilizing three methods: rototilling, pressure injection, and surface application. An undisturbed soil core (10 cm deep, 10 cm wide, 2.5 cm thick) was taken from each plot 30 days after treatment. Soil pH was measured at 1-cm horizontal and vertical intervals with a pH-sensitive glass microelectrode. Horizontal and vertical variations of soil pH were estimated by variance analyses, and the spatial variability was assessed by semivariogram function. Addition of H3PO4 to the soil decreased pH significantly and increased total variability in the measured zone. The pH variability in the vertical direction differed significantly, but that in the horizontal did not. Higher total variability caused by the treatment methods resulted from increased spatially dependent variability, which may be attributed to strong trends of pH with soil depth. Rototilling resulted in the lowest variation and smallest spatial variances, suggesting the most effective mixing of soil with added H3PO4 among the methods tested. This study demonstrated that microscale pH measurements and analyses of total and spatial variances may aid in assessing the efficacy of H3PO4 treatment in Pb-contaminated soil.

Cleanup goals for sites affected by inorganic contaminants often are established on the basis of risk assessments, and these assessments rely an the estimated oral toxicity of the substances of concern. These toxicity estimates typically are based on historical studies in which a soluble salt of the metal was dissolved in water or mixed in food and then ingested by an animal or human. However, these toxicity studies do not account for the characteristics of a metal in soil or the limitations that these characteristics place on enteric absorption of that metal. Therefore, a more accurate risk assessment must account for the bioavailability of the metal in site-specific soil, relative to the bioavailability of the metal in the form administered in the toxicity study (i.e., the relative bioavailability of the element in soil). Historically, relative bioavailability estimates for metals in soil have been based on in vivo studies in laboratory animals. Given the costs and time constraints associated with such studies, it is clear that a more efficient alternative is desirable. The most promising option involves the development and validation of in vitro extraction tests that are predictive of oral metals bioavailability from soil. Such tests would provide a rapid and inexpensive method for developing more accurate exposure estimates for use in human health risk assessments. This paper reviews the site-specific in vivo studies that have been conducted to estimate the relative bioavailability of arsenic and lead in soil, discusses the soil and mineralogical factors that influence the bioavailability of these elements, and reviews the research to date on the development of bioavailability-predictive extraction tests for metals in soil. Finally, this paper outlines an ongoing collaborative research project to formally validate an in vitro extraction test for use in estimating the oral bioavailability of arsenic and lead in soil.

Sera obtained from a group of pigs (n = 5) fed a diet amended with fumonisin containing Fusarium moniliforme culture material was used to determine the levels of Tumor Necrosis Factor-Alpha (TNF) activity by a functional bioassay utilizing the TNF sensitive WEHI 140 mouse fibrosarcoma cell line. Two pigs developed signs consistent with pulmonary edema which was confirmed by pathologic examination in only one pig. Significant, time dependent increases in TNF-like activity were observed in all pigs during the five days of the trial. Another group of pigs (n = 5) was given a defined daily dose of the same culture material by gastric intubation. Two pigs developed fulminant pulmonary edema and sharp increases in TNF activity were observed during the 3 days of the trial in all pigs. In both cases the activity was not abrogated by addition of a neutralizing anti-human TNF monoclonal antibody suggesting that other factors may have been responsible for these effects, possibly the increased levels of sphingoid bases in the serum. Since the pig has become an important model in the study of TNF mediated endotoxic shock, these studies illustrate the relevance of certifying the absence of this important mycotoxin from corn based animal diets, specially if functional assays are used to monitor the activity of TNF in serum.

could be in jeopardy because of the loss of elasticity of the bulbus and the subsequent impaired output. However, the more sedentary and noncompetitive environment of farmed fish may eliminate the necessity for sudden increases of cardiac output. Similar findings have been described in farmed Atlantic salmon (Salmo salar) with pancreas disease, where clinical signs may not be observed in affected fish despite an associated cardiomyopathy.

Five adult horses presented with acute clinical signs of watery diarrhea, excessive salivation, muscle tremors, ataxia, and depression. Four died within 24 hours and the fifth was euthanatized approximately 48 hours after onset of clinical signs. Necropsy findings in two of the horses included hyperemia of gastric mucosa, intestines filled with green to black watery fluid, and multifocal to coalescing, hemorrhagic 1.0-2.0-cm-diameter ulcers of the mucosa of the cecum and large colon. Histopathologic changes in the cecum and large colon consisted of mucosal necrosis and ulceration, vascular thrombosis, necrosis of submucosal blood vessels, and infiltration by mixed mononuclear inflammatory cells and neutrophils. Arsenic toxicosis was suspected. The owner had not been feeding the horses any grain; however a mixture of grain and pink powder was found in the pasture. Liver arsenic concentrations in the two horses were 14.0 and 11.0 ppm, a sample of renal cortex contained 108 ppm arsenic, and the grain/powder mixture found in the pasture was positive for arsenic at >3,000 ppm. Kidney lead concentrations were 6.5 and 4.2 ppm. Results were consistent with lead arsenate or lead arsenite poisoning.

12,13-epoxytrichothec-9-en-8-one) is a naturally occurring trichothecene toxin produced by several Fusarium fungi that parasitize numerous cereal grains. Numerous species of Fusarium have been found to produce DON. The genus Fusarium occurs throughout the world and may affect corn, wheat, barley, oats, rice, and sorghum and complete feed formulations. Cereal grain contamination by DON occurs most frequently when conditions are cool and wet at the time of grain formation and harvest and is associated predominantly with infection in the field rather than as a complication of storage. 7 Although most descriptions of widespread grain contamination by DON have been confined to temperate zones of the world, DON contamination has also been reported to affect grain in subtropical climates. Deoxynivalenol has been given the trivial name vomitoxin because it causes emesis when ingested by swine and dogs. Other clinical effects attributed to the toxic effects of ingested DON include feed refusa1, decreased weight gain, signs of gastrointestinal irritation (e.g., diarrhea, colic, rectal prolapse, hematochezia), thickening of the squamous aspect of the gastric lining of pigs, reproductive problems, skin irritation, cardiotoxicity, and interference with the immune system. 16 The extent to which DON causes clinical signs of toxicosis is proportional to its concentration in contaminated feed. Ingested DON also affects intestinal immunoglobulin synthesis. Specifically, DON stimulates intestinal IgA production in mice, leading to an elevated concentration of circulating IgA, increased polymeric : monomeric IgA ratio, and accumulation of IgA in the renal mesangium. The renal damage that occurs following DON ingestion has been characterized as a possible autoimmune phenomenon consequent to the entrapment of circulating IgA immune complexes in the mesangium. 14 IgA nephropathy, which is the most common form of glomerulonephritis in human beings worldwide, affects men 2-5 times more commonly than it affects women. Although the cause of IgA glomerulonephritis is unknown, similarities between the clinical syndrome in human beings and experimental DON intoxication in laboratory animal species (e.g., IgA dysregulation, renal micropathology, evidence that testosterone may be a cofactor in experimental DON-induced IgA glomerulonephritis) suggest that DON may be important in the pathogenesis of IgA glomerulonephritis in human beings. Glomerulonephritis is a common finding at necropsy and represents an important cause of chronic renal failure in horses. Chronic renal failure is comparatively uncommon in horses, and glomerulonephritis is most frequently recognized

Normally innocuous forages are sporadically associated with hepatogenous photosensitization outbreaks at certain times of the year or when grown and harvested during unusual environmental conditions, such as periods of excessive rainfall. Allegations of livestock illness following consumption of such moldy hays are associated with clinical syndromes uncharacteristic of known forage-related diseases, suggesting that unidentified toxin(s) may be responsible. This study was instigated by field observations of hepatogenous photosensitization in cattle fed alfalfa-grass forage. To document the toxic nature of the hay, large bales of hay (450 kg) were fed, ad libitum, to 3 groups of 2 calves each. Elevated serum liver enzymes provided evidence of hepatobiliary disease. Gamma glutamyl transferase activities in serums of the calves sustained at least a 10-fold increase above baseline during the feeding trials. Histologic examination of liver biopsies and postmortem sections revealed mild periportal fibrosis and biliary hyperplasia. Culture material from 12 fungal isolates from the hay failed to induce liver disease in calves.

Amaranthus retroflexus (redroot pigweed)-induced nephrotoxicity was diagnosed in 6 herds of cattle from 3 counties in southwest Missouri. Forty-eight cows and calves died and another 35 were clinically affected. Serum urea nitrogen concentration, determined in 4 affected calves, was between 55 and 284 mg/dl, and serum creatinine concentration was between 6.7 and 29.9 mg/dl. Postmortem examination of affected cows and calves revealed amber-colored fluid in peritoneal cavities and retroperitoneal perirenal edema. Histologic examination of kidney sections revealed widespread degeneration and necrosis of proximal and distal tubules. Compared with archived kidney sections from cattle with Quercus (oak) poisoning, distal renal tubules were more severely affected. Oak poisoning also was associated with a higher prevalence of interstitial fibrosis and renal tubular oxalosis. We concluded that ingestion of the aerial and leafy portions of pigweed by cattle in drought situations does not necessarily lead to nitrate-induced sudden death associated with consumption of the nitrate-containing stems.

The purpose of this study was to investigate potential detrimental effects of fumonisin B1 on the developing hamster. In experiments 1 and 2, timed-bred hamsters were dosed with 0.0 to 12.0 mg fumonisin B1/kg from day 8 to day 10 or day 12 of gestation. Clinical signs of material toxicity were not observed. Pregnant animals had reduced weight gains and lower total bilirubin levels than nonpregnant females. Hamsters were euthanized on day 15 of gestation. Histologic evaluation revealed autolytic placental changes expected in terminal gestation, as well as more advanced placental necrosis in association with fetal resorptions. Mean fetal weights and crown-rump lengths of living term fetuses on a per-litter basis did not differ between untreated controls and treated animals given 6.0 mg fumonisin B1/kg or less. However, at higher doses of fumonisin B1, there was an increased incidence of prenatal losses (deaths and resorptions). A greater percentage of litters had 1 or more fetuses affected, and a greater percentage of total fetuses were lost/litter as the fumonisin dosage increased. At 12.0 mg/kg, all litters were affected and 100% of the fetuses were dead and resorbing. Fumonisin B1 appears a developmental toxicant in hamsters. Toxicity is manifest by increased numbers of prenatal deaths and resorptions at doses that do not induce clinicopathologic evidence of maternal toxicity.

A sudden onset of bizarre neurologic dysfunction was found in 8 of 90 mixed-breed feeder calves. Seven other calves were dead, and 3 more died during the next week. A diagnosis of organochlorine toxicosis was made when rumen and abomasal contents from 1 of the calves revealed 22.4 and 20.6 micrograms of aldrin/g of ingesta, respectively. Complete feeds retrieved from self-feeders contained 54 and 528 micrograms of aldrin/g of feed. The initial concentration range in fat from 40 live calves was 6.01 to 42.44 micrograms of dieldrin/g of fat. Additional fat samples were analyzed to verify residue compliance until the entire herd was clear of residue 18 months after removal of the contaminated ration. The range of apparent half-lives for dieldrin in body fat of heifers and steers was 69 to 231 and 53 to 116 days, respectively. These findings demonstrate the considerable variability in apparent half-life of dieldrin in field cases. In cases of dieldrin-contaminated livestock, veterinarians and regulatory personnel must accurately determine the necessary slaughter withholding times so that informed economic decisions are made in the best interest of the producer while enhancing the probability of a safe food supply. Excretion rates of dieldrin from field-contaminated cattle may not be consistent with results obtained under experimental conditions.

The potbellied pig was introduced into the United States in 1985 and has since become a desirable pet throughout the country. When seeking medical or husbandry advice, pig owners often seek the counsel of their local small animal practitioner. The practitioner may feel at a loss to adequately respond to requests for veterinary care because they do not remember pig medicine from veterinary school. Large animal practitioners, who have knowledge of the medicine and surgery of commercial pigs, often do not like caring for potbellied pigs because they are pets and not production animals. This article is intended to provide the small animal practitioner with some practical knowledge in the husbandry and medical care of the pet pig, also known as the yuppy puppy.