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Over a 3-yr period 336 MT/ha of dried sewage sludge, from a municipal waste treatment plant, was applied in liquid form to land subsequently used to grow corn. The sludge contained 115 mg Cd, 4,200 mg Zn and 538 mg Ni/kg dry matter and comprised the solids remaining after treatment of the waste waters of approximately 260 industries as well as domestic users. Corn grain harvested from the plot amended with sewage sludge (SA corn) or corn grown on a plot without sludge addition (control corn) was fed to a total of 56 pigs to determine the effect on growth performance and parameters indicative of toxicity. Each treatment consisted of seven pens of four pigs each with an average initial weight of 17.6 kg. The growth trial was terminated when pigs weighed approximately 90 kg. No differences were observed between treatment groups for average daily gain, feed: gain ratio or daily feed intake. Higher (P<.01) concentrations of Cd, Ni and Zn were found in SA corn compared with the control corn. This resulted in higher (P<.01) concentrations of Cd in kidney and liver and Ni in kidney of pigs fed SA corn as compared with pigs fed control corn. No significant differences were observed in Cd or Ni concentrations in muscle or in hepatic microsomal mixed-function oxidase (MFO) activity and liver:body weight ratios, which is indicative of the absence or low levels of organic toxicants in SA corn. In addition, no significant treatment effects were observed when corn, feces and urine samples were evaluated for the presence of mutagenic substances. Histopathologic analysis of various tissues for lesions demonstrated that pigs fed SA corn were not adversely affected.

Aquatic plants harvested from Cayuga Lake in New York were dried, milled and incorporated into a pelleted ration replacing 35% by weight of alfalfa meal. The ration was fed to pregnant goats and to sheep for 130 days. Analysis of the aquatic plants for 40 elements and polychlorinated biphenyls showed no toxic concentrations. There were no significant differences (P>.05) in feed intake, rate of weight gains or ration digestibility between the animals fed the aquatic ration and those fed the control ration. The aquatic ration was notably higher in ash and lower in fat, fiber and energy than was the control ration. All kids born were normal. Gross pathologic and histologic examination of animal tissues revealed no notable differences between animals fed the aquatic and control rations.

Two experiments were completed with a total of 54 5- to 7-week-old weanling Yorkshire pigs to determine (Experiment 1) the tissue retention of dietary selenium (Se) present in white sweet clover (Melilotus alba) relative to that provided as sodium selenite (Na2SeO3) and (Experiment 2) the tissue retention and liver distribution of Se present in fly ash incorporated into the diet.In Experiment 1, groups of four pigs each were randomly allotted to corn-soybean meal-type diets containing 5 or 10% white sweet clover grown either in low Se soil (.03 ppm Se in clover) or on fly ash (70 ppm Se in clover). Na2SeO3was added to the low Se clover diets to provide 0, 3.5 or 7.0 ppm of Se. Se concentrations of kidney, liver and skeletal muscle after 61 days were increased more by fly-ash grown sweet clover than by Na2SeO3, but blood Se was increased more by Na2SeO3. No histopathological lesions were found in liver, kidney, heart, pancreas or skeletal muscle. Diets had no effect on weight gain or feed to gain ratio.In Experiment 2, 30 pigs were fed from weaning to 92 kg slaughter weight on a corn soybean meal-type diet containing 0, 1, 2, 4 or 8% fly ash (5.7 ppm Se). Fly ash had no effect on weight gain and no histopathological lesions were found in heart, liver, kidney, pancreas or skeletal muscle. Tissue Se concentrations increased progressively with graded levels of fly ash in the diet. Distribution of Se in eight different sites in the liver was uniform. It is concluded that Se supplied in the diet as a component of fly ash or of white sweet clover grown on fly ash (probably as a constituent of seleno-amino acids) is absorbed and utilized for tissue deposition by the pig. The toxicological potency of clover-borne Se and its ability to alleviate vitamin E - Se deficiency signs relative to that of Na2SeO3remain unknown.

In view of the potential exposure of sewage treatment workers to a multitude of mutagenic substances, the frequency of urinary mutagens was measured by the Ames test among a sample of 164 sewage treatment workers employed in 14 sewage treatment plants which processed between 3 and 10 million gallons of sewage daily in New York State between March and July, 1984. The frequency was compared to that observed in 72 water treatment employees in the same municipalities. Sewage workers had a significantly higher risk for urinary mutagens after controlling for smoking, using the Ames test, both with and without the addition of the liver microsomal homogenate, S-9. More precise methods of measuring exposure in epidemiologic studies, particularly in environmental and occupational epidemiology, are in various stages of development. The application of one of these methods, the Ames test, to an occupational group (sewage workers) with potentially high exposure to mutagenic substances is described and the strengths and limitations of this application are discussed.

Previous work has shown that the efficacy of cancer prevention by selenium-enriched garlic (Se-garlic) is primarily dependent on the action of selenium. An aqueous extract containing 43 micro Se/ml was prepared from lyophilized Se-garlic powder by the Soxhlet method. The activity of this Se-garlic extract was evaluated in a transformed mammary epithelial cell culture model for its effect on cell morphology, cell growth, cell cycle progression and the induction of single and double stranded breaks in DNA. Comparisons were also made with a similarly prepared extract from regular garlic, Se-methylselenocysteine (a major water-soluble seleno-amino acid identified in Se-garlic) and selenite (used for fertilizing Se-garlic). In contrast to the regular garlic extract which produced little or no modulation of the above parameters, treatment with the Se-garlic extract resulted in growth inhibition, GI phase cell cycle arrest and apoptotic DNA double strand breaks in the absence of DNA single strand breaks. This pattern of cellular responses was duplicated with exposure to Se-methylselenocysteine. Selenite, on the other hand, induced cell cycle blockage in the S/G2-M phase, and a marked increase in DNA single strand breaks (a measure of genotoxicity) in addition to growth suppression. The chemopreventive efficacy of the two garlic extracts was also investigated in the rat methylnitrosourea mammary tumor model. Both extracts were supplemented in the diet for 1 month immediately following carcinogen administration. Significant cancer protection was observed with treatment by the Se-garlic extract (at 3 p.p.m. Se in the diet), while little benefit was noted with treatment by the regular garlic extract. Based on the above in vitro and in vivo findings, it is hypothesized that the Se-garlic extract, in part via the action of Se-methylselenocysteine, is able to inhibit tumorigenesis by suppressing the proliferation and reducing the survival of the early transformed cells. Furthermore, the data also support the concept that the modulation of certain in vitro markers may be of value in predicting the effectiveness of novel forms of selenium for cancer prevention.

Previous work has shown that the efficacy of cancer prevention by selenium-enriched garlic (Se-garlic) is primarily dependent on the action of selenium. Additionally, supplementation of Se-garlic inhibited the post-initiation phase of mammary carcinogenesis when it was given continuously to the animals. In this report, experiments were carried out in which treatment with the Se-garlic was started after carcinogen dosing (DMBA or MNU) but was restricted to either the early or late stage of neoplastic progression. The results from these two models showed that a short-term exposure to the Se-garlic for 1 month immediately following carcinogen administration was just as effective in cancer prevention as the continuous exposure regimen (5 months), suggesting that the Se-garlic may irreversibly alter the process of clonal expansion and/or selection of transformed cells during their early stage of development. Plasma and mammary tissue selenium levels essentially returned to basal levels at 1 month after withdrawal of supplementation. These observations imply that the outcome of cancer protection by short-term Se-garlic intervention was not due to a slow turnover, and therefore a lingering presence, of selenium in the target organ or in the circulation. The above finding was in contrast to that of a second study in which Se-garlic was supplemented starting at 13 weeks after carcinogen treatment. With this protocol, the number of new tumors and the number of new tumor-bearing rats found during the intervention period (weeks 13 to 22) were not statistically different between the control and supplemented groups, suggesting that Se-garlic had a minimal effect on the later stages of mammary carcinogenesis.

Methods employing an anion‐exchange resin were found to predict with a high degree of accuracy the phosphorus needs of soils as determined by crop responses to applications of phosphatic fertilizer.