Abstract  This report consists of charts of toxic pollutants with the recommended water quality criteria listed for such things as freshwater, saltwater, human consumption, etc.

Abstract  The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards (40 CFR part 50) for pollutants considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings. The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient Air Quality Standards for six principal pollutants, which are called "criteria" pollutants. They are listed below. Units of measure for the standards are parts per million (ppm) by volume, parts per billion (ppb - 1 part in 1,000,000,000) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (µg/m3).

Abstract  The objectives of this study were to compare the effects of technetium and uranium on the yield and uptake, and to identify the organ of accumulation, of an edible leafy vegetable growing in sandy and peaty soils. In sand, where the soil's sorption capacity is negligible, technetium uptake is four orders of magnitude higher than from peat, suggesting no plant mediation of uptake and thus a constant concentration factor (>50) in an oxidizing environment where technetium is continuously supplied. The technetium is predominantly translocated to the shoots. When soil fixation occurs, as in peat, this becomes the controlling factor in the plant uptake of technetium. In the case of uranium, plant mediation is more significant. Uranium uptake by Swiss chard is up to 80 times higher from sand than from peat. The uranium is restricted to the root system and may only be precipitated on the outer root membrane and may not accumulate in the roots.

Abstract  Rats of various postnatal ages were utilized to investigate developmental changes in the short-term distribution of [3H]mannitol, [3H]inulin and [51Cr]-tagged erythrocytes in both the cerebellum (CER) and cerebral cortex (CC). As the CNS undergoes maturation the most precipitous decrease in the 1-h radiomannitol (and inulin) space in the CER takes place during the second postnatal week whereas the greatest reduction in the spaces for both radioisotopes in the CC occurs during the earlier period between 0.5 and 1 week. The volume of distribution in immature brain tissue (1 week) into which [3H]mannitol penetrates in 1 h is substantially less (by 75--90%) than that into which this tracer permeates in non-neural tissue such as heart and liver; thus, even prior to the proliferation of glial elements, there is a limited barrier effect. At 3 weeks the permeability of the blood--brain barrier in the CER to mannitol is comparable to that in the CC. The vascularity of the CER (as estimated by residual [51Cr]erythrocyte-volume) is greater than that of the CC at each postnatal age investigated. The uptake of radiomannitol by the choroid plexus (blood--CSF barrier) in immature animals is a reflection primarily of developmental changes in volume of extracellular fluid rather than in permeability of the basolateral face of the choroidal epithelium. Qualitative differences, neonates vs adults, in the distribution of [3H]mannitol between CSF and brain tissue are attributable to maturational changes in secretory and permeability phenomena associated with the blood--CSF and blood--brain barriers.

Abstract  The process of assessing the risk associated with human exposure to environmental chemicals inevitably relies on a number of assumptions, estimates and rationalizations. One of the more challenging aspects of risk assessment involves the need to extrapolate beyond the range of conditions used in experimental animal studies to predict anticipated human risks. The most obvious extrapolation required is that from the tested animal species to humans; but others are also generally required, including extrapolating from high dose to low dose, from one route of exposure to another and from one exposure timeframe to another. Several avenues are available for attempting these extrapolations, ranging from the assumption of strict correspondence of dose to the use of statistical correlations. One promising alternative for conducting more scientifically sound extrapolations is that of using physiologically based pharmacokinetic models that contain sufficient biological detail to allow pharmacokinetic behavior to be predicted for widely different exposure scenarios. In recent years, successful physiological models have been developed for a variety of volatile and nonvolatile chemicals, and their ability to perform the extrapolations needed in risk assessment has been demonstrated. Techniques for determining the necessary biochemical parameters are readily available, and the computational requirements are now within the scope of even a personal computer. In addition to providing a sound framework for extrapolation, the predictive power of a physiologically based pharmacokinetic model makes it a useful tool for more reliable dose selection before beginning large-scale studies, as well as for the retrospective analysis of experimental results.

Abstract  Endometriosis is a disease which afflicts women of reproductive age. It is one of the most common causes of pelvic pain and infertility; an estimated 5 million women in the U.S. are affected.1 Despite its apparent widespread occurrence, there are no national or international surveillance systems to determine how many suffer from this disease. Since there is no noninvasive test that is highly selective and specific for endometriosis, studies of its prevalence and incidence have been limited to women undergoing gynecologic operations.

Abstract  Because many diseases of the Western Hemisphere are hormone-dependent cancers, we have postulated that the Western diet, compared to a vegetarian or semivegetarian diet, may alter hormone production, metabolism, or action at the cellular level by some biochemical mechanisms. Recently, our interest has been mainly focused on the cancer-protective role of some hormonelike diphenolic phytoestrogens of dietary origin, the lignans and the isoflavonoids. The precursors of the biologically active compounds originate in soybean products (mainly isoflavonoids), whole grain cereal food, seeds, and probably berries and nuts (mainly lignans). The plant lignan and isoflavonoid glycosides are converted by intestinal bacteria to hormonelike compounds with weak estrogenic but also antioxidative activity; they have now been shown to influence not only sex hormone metabolism and biological activity but also intracellular enzymes, protein synthesis, growth factor action, malignant cell proliferation, differentiation, and angiogenesis in a way that makes them strong candidates for a role as natural cancer-protective compounds. Epidemiologic investigations strongly support this hypothesis because the highest levels of these compounds in the diet are found in countries or regions with low cancer incidence. This report is a review on recent results suggesting that the diphenolic isoflavonoids and lignans are natural cancer-protective compounds.

Abstract  The rationale for adjusting occupational exposure limits for unusual work schedules is to assure, as much as possible, that persons on these schedules are placed at no greater risk of injury or discomfort than persons who work a standard 8 hr/day, 40 hr/week. For most systemic toxicants, the risk index upon which the adjustments are made will be either peak blood concentration or integrated tissue dose, depending on what chemical's presumed mechanism of toxicity. Over the past ten years, at least four different models have been proposed for adjusting exposure limits for unusually short and long work schedules. This paper advocates use of a physiologically-based pharmacokinetic (PB-PK) model for determining adjustment factors for unusual exposure schedules, an approach that should be more accurate than those proposed previously. The PB-PK model requires data on the blood:air and tissue:blood partition coefficients, the rate of metabolism of the chemical, organ volumes, organ blood flows and ventilation rates in humans. Laboratory data on two industrially important chemicals--styrene and methylene chloride--were used to illustrate the PB-PK approach. At inhaled concentrations near their respective 8-hr Threshold Limit Value-Time-weighted averages (TLV-TWAs), both of these chemicals are primarily eliminated from the body by metabolism. For these two chemicals, the appropriate risk indexing parameters are integrated tissue dose or total amount of parent chemical metabolized. Since methylene chloride is metabolized to carbon monoxide, the maximum blood carboxyhemoglobin concentrations also might be useful as an index of risk for this chemical.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract  The first of a series of reports recommending Annual Limits for Intakes (ALI’s) of radionuclides by workers. This report includes the main text for the whole series of Publication 30, and data on twenty one elements having radioisotopes that are of considerable importance in radiological protection. The actual ALI values in ICRP Publication 30 have become obsolete with the newer dosimetry and dose limits of ICRP Publication 60, and at present the dose coefficients in ICRP Publications 68, 69, 71, and 72 should be used to determine ALI’s. However, the vast body of biokinetic information in Publication 30 still forms the basis of much of the calculations underlying those later reports.

Abstract  U(VI), Np(VI), and Pu(VI) borates with the formula AnO(2)[B(8)O(11)(OH)(4)] (An = U, Np, Pu) have been prepared via the reactions of U(VI) nitrate, Np(VI) perchlorate, or Pu(IV) or Pu(VI) nitrate with molten boric acid. These compounds are all isotypic and consist of a linear actinyl(VI) cation, AnO(2)(2+), surrounded by BO(3) triangles and BO(4) tetrahedra to create an AnO(8) hexagonal bipyramidal environment. The actinyl bond lengths are consistent with actinide contraction across this series. The borate anions bridge between actinyl units to create sheets. Additional BO(3) triangles and BO(4) tetrahedra extend from the polyborate layers and connect these sheets together to form a three-dimensional chiral framework structure. UV-vis-NIR absorption and fluorescence spectroscopy confirms the hexavalent oxidation state in all three compounds. Bond-valence parameters are developed for Np(VI).

Abstract  We investigate the electronic and band structure for the (8; 0) single-wall carbon nanotube (SWCNT) with a europium (Eu) and a uranium (U) atom outside by using the first-principles method with the density functional theory (DFT). The calculated band structure (BS), total density of state (TDOS), and projected density of state (PDOS) can elucidate the differences between the pure (8; 0) SWCNT and the nuclei outside the SWCNT. The indirect band gaps are obtained when Eu and U atom are put outside the (8; 0) CNT; they are 0.037 eV and 0.036 eV, respectively, which is much smaller than 0.851 eV for pure CNT. Compared with pure (8; 0) SWCNT, the bottom of the conduction band moves down by 0.383 eV and 0.451 eV with the Eu and U outside, and the top of valence band moves up by 0.127 eV and 0.162 eV, respectively. More significantly, the top of the valence band has exceeded the fermi-level. So, a single nucleus changes the semiconductor character of pure nanotube to semi-metal.

Abstract  The concentrations of uranium, thorium, barium, nickel, strontium and lead in the samples of the tailings and plant species collected from a uranium mill tailings repository in South China were analyzed. Then, the removal capability of a plant for a target element was assessed. It was found that Phragmites australis had the greatest removal capabilities for uranium (820 μg), thorium (103 μg) and lead (1,870 μg). Miscanthus floridulus had the greatest removal capabilities for barium (3,730 μg) and nickel (667 μg), and Parthenocissus quinquefolia had the greatest removal capability for strontium (3,920 μg). In this study, a novel coefficient, termed as phytoremediation factor (PF), was proposed, for the first time, to assess the potential of a plant to be used in phytoremediation of a target element contaminated soil. Phragmites australis has the highest PFs for uranium (16.6), thorium (8.68), barium (10.0) and lead (10.5). Miscanthus floridulus has the highest PF for Ni (25.0). Broussonetia papyrifera and Parthenocissus quinquefolia have the relatively high PFs for strontium (28.1 and 25.4, respectively). On the basis of the definition for a hyperaccumulator, only Cyperus iria and Parthenocissus quinquefolia satisfied the criteria for hyperaccumulator of uranium (36.4 μg/g) and strontium (190 μg/g), and could be the candidates for phytoremediation of uranium and strontium contaminated soils. The results show that the PF has advantage over the hyperaccumulator in reflecting the removal capabilities of a plant for a target element, and is more adequate for assessing the potential of a plant to be used in phytoremediation than conventional method.

Abstract  Seventy-three rats were exposed to an aerosol of enriched uranium dioxide (UO2), giving initial lung burdens of 26 to 447 micrograms at 6 days post-inhalation (PI). At 7 days PI 35 of these rats were further exposed to thermalised neutrons at a fluence of 1 x 10(12) neutrons cm-2. There was no significant difference between the two groups in the clearance rate of the UO2 particles from the lung, up to 590 days PI. The particles cleared relatively slowly over this period with a retention half-time in the lung of 160 to 176 days. Transmission electron microscope (TEM) studies of tissue from the alveolar region at 8 days PI showed that inhalation of UO2 particles significantly increased the sizes of macrophage and type II cells, and the number of macrophage and type I cells. There was also a significant increase in the size of lysosomal granules within the macrophages after exposure to the UO2 particles. The exposure to UO2, neutrons and 235U fission fragments had no significant effect on any of the cells above that observed in the animals exposed to UO2 alone. Additional rats were exposed to the same neutron fluence without prior UO2 inhalation. The alveolar cells of neutron-only exposed rats were, in size and number, typically no different from those in the completely unexposed control rats.

Abstract  Ceramic and non-ceramic forms of uranium dioxide, produced industrially, were administered to rats either by inhalation or as an aqueous suspension which was injected directly into the pulmonary region of the lungs. The results showed that: 1 both materials should be assigned to inhalation class Y as defined by the International Commission on Radiological Protection; 2 whilst the translocation of uranium to the blood for the non-ceramic UO2 was about twice that obtained for the ceramic form, the two dioxides were unlikely to be differentiated on the basis of their lung retention kinetics; 3 the distribution of uranium amongst body tissues and the relationship between systemic content and cumulative urinary excretion indicated that it was transported in the hexavalent form; 4 in addition to air sampling procedures, lung radioactivity counting measurements could be used to advantage for assessing occupational exposures; 5 the exposure limits should be based on radiation dose rather than chemical toxicity.

Abstract  The acute oral and subcutaneous toxicity of uranium (7440611) was investigated in rats and mice. Male Sprague-Dawley-rats and male Swiss-mice were administered single doses of uranyl-acetate (541093), subcutaneously or intragastrically. The median lethal dose (LD50) 14 days following subcutaneous administration was 8.3 and 20.4mg/kg for rats and mice, respectively; and the oral LD50 for rats was 204mg/kg and for mice was 242mg/kg. Most deaths occurred 5 to 8 days following uranyl-acetate administration. Physical signs of toxicity, usually evident after 6 days and persisting through the 14 day experimental period, included: weight loss, piloerection, rubefaction, tremors, hypotension, pupillary constriction, exophthalmos, and mild hemorrhages in eyes, nose, and legs. In a separate experiment, rats and mice were administered single doses of 210mg/kg uranyl-acetate subcutaneously or 10mg/kg intragastrically. Animals were observed for 14 days and then survivors were sacrificed and examined for pathological changes. Significant weight loss was observed in all treated animals. Food intake and amount of feces excreted were significantly reduced. Water consumption was not changed, but the volumes of urine excreted were significantly increased. Plasma urea and creatinine were significantly increased 7 days following either oral or subcutaneous uranyl-acetate administration. Histopathologic examination of the kidneys and liver revealed minimal lesions in animals administered uranyl-acetate orally, and more severe lesions in animals administered uranyl-acetate subcutaneously. The authors conclude that renal toxicity is the most characteristic response to uranyl-acetate, which is highly toxic when administered subcutaneously and moderately toxic when administered orally.