Showing papers in "Environmental Health Perspectives in 1981"
TL;DR: Present evidence indicates that the trivalent chromium compounds do not cause cancer although high concentrations in some in vitro systems have shown genetic toxicity, and proper action should be taken in all industries with regard to such exposure.
Abstract: The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Present evidence indicates that the trivalent chromium compounds do not cause cancer although high concentrations in some in vitro systems have shown genetic toxicity. Hexavalent chromium compounds cause cancer in humans, in experimental animals and exert genetic toxicity in bacteria and in mammalian cells in vitro. Epidemiological evidence and animal experiments indicate that the slightly soluble hexavalent salts are the most potent carcinogens, but proper identification and characterization of exposure patterns in epidemiological work are lacking. Workers also tend to have mixed exposures. Soluble and slightly soluble salts are equally potent genotoxic agents in vitro. Further work for establishing dose estimates for risk evaluation in epidemiological work is important. In vitro systems should be applied for further identification of the mechanism of the carcinogenic effects, and animal experiments are urgent for comparison of the carcinogenic potency of the different hexavalent salts. Hexavalent chromium salts must be regarded as established carcinogens, and proper action should be taken in all industries with regard to such exposure. At present the carcinogenic risk to the general population caused by chromium compounds seems to be negligible, chromium in cigarettes, however, is an uncertainty in this respect. The amount of chromium and the type of chromium compounds inhaled from cigarettes is not known.
238Â citations
TL;DR: An overview is presented of the current state of knowledge of the salient aspects of the sources, transport, and alterations of arsenic, beryllium, cadmium, chromium, and nickel, in the hope of permitting a more facile identification and quantification of the potential hazard to exposure to these agents.
Abstract: An overview is presented of the current state of knowledge of the salient aspects of the sources, transport, and alterations of arsenic, beryllium, cadmium, chromium, and nickel. This information is considered vital for a better assessment of the scope of potential human hazard to these ubiquitous toxicants and their compounds. Stress is focused on both natural and industrial activities, particularly on the latter's projected trends. Increasing use patterns per se of most of these metals, as well as aspects of waste disposal and the anticipated increased combustion of fossil fuels for power generation and space heating (particularly in the United States), are major causes of potential health concern. Additionally, attention is drawn to the need for increased research to fill the gaps in our knowledge in these vital areas, all in the hope of permitting a more facile identification and quantification of the potential hazard to exposure to these agents.
190Â citations
TL;DR: The oxyanions of vanadium, chromium, molybdenum, arsenic, and selenium are stable forms of these elements in high oxidation states which cross cell membranes using the normal phosphate and/or sulfate transport systems of the cell.
Abstract: The oxyanions of vanadium, chromium, molybdenum, arsenic, and selenium are stable forms of these elements in high oxidation states which cross cell membranes using the normal phosphate and/or sulfate transport systems of the cell. Once inside the cell, these oxyanions may sulfuryl transfer reactions. Often the oxyanions serve as alternate enzyme substrates but form ester products which are hydrolytically unstable compared with the sulfate and phosphate esters and, therefore, decompose readily in aqueous solution. Arsenite and selenite are capable of reacting with sulfhydryl groups in proteins. Some cells are able to metabolize redox active oxyanions to forms of the elements in other stable oxidation states. Specific enzymes may be involved in the metabolic processes. The metabolites of these elements may form complexes with small molecules, proteins and nucleic acids which inhibit their ability to function properly. The divalent ions of beryllium, manganese, cobalt, nickel, cadmium, mercury, and lead are stable forms of these elements which may mimic essential divalent ions such as magnesium, calcium, iron, copper, or zinc. These ions may complex small molecules, enzymes, and nucleic acids in such a way that the normal activity of these species is altered. Free radicals may be produced in the presence of these metal ions which damage critical cellular molecules.
173Â citations
TL;DR: The evidence of an etiologic role of arsenic for angiosarcoma of the liver is highly suggestive; however, the association between arsenic and cancer of other sites needs further investigation, and epidemiological data suggest that the present WHO standard for drinking water provides only a small safety margin with regard to skin cancer.
Abstract: A carcinogenic role of inorganic arsenic has been suspected for nearly a century. Exposure to inorganic arsenic compounds occurs in some occupational groups, e.g., among smelter workers and workers engaged in the production and use of arsenic containing pesticides. Substantial exposure can also result from drinking water in certain areas and the use of some drugs. Tobacco and wine have had high As concentrations due to the use of arsenic containing pesticides. Inorganic arsenic compounds interfere with DNA repair mechanisms and an increased frequency of chromosomal aberrations have been observed among exposed workers and patients. Epidemiological data show that inorganic arsenic exposure can cause cancer of the lung and skin. The evidence of an etiologic role of arsenic for angiosarcoma of the liver is highly suggestive; however, the association between arsenic and cancer of other sites needs further investigation. No epidemiological data are available on exposure to organic arsenic compounds and cancer. Animal carcinogenicity studies involving exposure to various inorganic and organic arsenic compounds by different routes have been negative, with the possible exception of some preliminary data regarding lung cancer and leukemia. Some studies have indicated an increased mortality from lung cancer in populations living near point emission sources of arsenic into the air. The role of arsenic cannot be evaluated due to lack of exposure data. Epidemiological data suggest that the present WHO standard for drinking water (50 micrograms As/l.) provides only a small safety margin with regard to skin cancer.
151Â citations
TL;DR: The thesis of this paper is that research upon, and efforts to prevent or minimize the harmful effects of noise have suffered from the lack of a full appreciation of the ways in which humans process and react to sound.
Abstract: The fundamental purposes of hearing are to alert and to warn. As a result sound directly evokes emotions and actions. The processing of sound by the brain is outlined to provide a biological and psychological basis for understanding the way in which sound can become a human stressor. The auditory orienting response, startle reflex and defensive response translate sound stimuli into action and sometimes into stress induced bodily changes through "fight or flight" neural mechanisms. The literature on the health and mental health effects of noise then is reviewed in the context of an integrated model that offers a holistic approach to noise research and public policy formulation. The thesis of this paper is that research upon, and efforts to prevent or minimize the harmful effects of noise have suffered from the lack of a full appreciation of the ways in which humans process and react to sound.
142Â citations
TL;DR: The presently available data are inadequate to assess the possible carcinogenicity of selenium compounds, but a few observations suggest that selenIUM may suppress the effect of other carcinogens administered to experimental animals and may even be associated with lower cancer mortality rates in man.
Abstract: The possible carcinogenicity of cobalt, iron, lead, manganese, mercury, platinum, selenium, and titanium is reviewed, taking into account epidemiological data, the results of animal experimental studies, data on mutagenic effects and on other in vitro test systems. Of the great variety of occupations where exposure to one of these metals may occur, only haematite mining has been clearly shown to involve an increased human cancer risk. While the possibility that haematite might in some way act as a carcinogen has to be taken into consideration it is more likely that other carcinogens are responsible. Certain platinum coordination complexes are used in cancer chemotherapy, are mutagenic, and likely to be carcinogenic. Cobalt, its oxide and sulfide, certain lead salts, one organomanganese, and one organotitanium compound have been shown to have a limited carcinogenic effect in experimental animal studies, and except for titanium appear to be mutagenic. Certain mercury compounds are mutagenic but none have been shown to be carcinogenic. The presently available data are inadequate to assess the possible carcinogenicity of selenium compounds, but a few observations suggest that selenium may suppress the effect of other carcinogens administered to experimental animals and may even be associated with lower cancer mortality rates in man. Epidemiological observations are essential for the assessment of a human cancer risk, but the difficulty in collecting past exposure data in occupational groups and the complexity of multiple occupational exposures with changes over time, limits the usefulness of retrospective epidemiological studies.
138Â citations
TL;DR: An animal bioassay has been used to evaluate a series of airborne chemicals for their sensory irritating properties to the upper respiratory tract and a good correlation was obtained between the predicted "safe" levels of exposure and current Threshold Limit Values established for industrial exposures.
Abstract: An animal bioassay has been used to evaluate a series of airborne chemicals for their sensory irritating properties to the upper respiratory tract. Teh results obtained can be used to rank their potency. An attempt has been made to predict "safe" levels of exposure for humans on the basis of this short-term assay. A good correlation was obtained between the predicted "safe" levels of exposure and current Threshold Limit Values established for industrial exposures.
136Â citations
TL;DR: The findings suggest the need for further study since other workplace-related factor(s) may be responsible for the elevated sperm abnormalities seen in this study, and a definitive link between carbaryl exposure and human seminal defects cannot be established.
Abstract: Semen was collected from 50 men occupationally exposed to carbaryl (1-naphthyl methyl carbamate) in a produciton plant for durations of 1 to 18 years and compared to semen from a control group of 3...
125Â citations
TL;DR: The results indicate that VC is a multipotential carcinogen, affecting a variety of organs and tissues, and to the authors' knowledge this is the largest experimental carcinogenicity study performed on a single compound by a single institution.
Abstract: Data are presented regarding the final results of the Bentivoglio (Bologna) project on long-term carcinogenicity bioassays of vinyl chloride (VC). The experimental project studied the effects of the monomer, administered by different routes, concentrations and schedules of treatment, to animals (near 7000) of different species, strains, sex and age. To our knowledge this is the largest experimental carcinogenicity study performed on a single compound by a single institution. The results indicate that VC is a multipotential carcinogen, affecting a variety of organs and tissues. In the experimental conditions studied, the neoplastic effects of the monomer were also detected at low doses. The experimental and biological factors greatly affect the neoplastic response to VC. Long-term carcinogenicity bioassays are, at present, a unique tool for the identification and quantification of environmental and occupational risks. Precise and highly standardized experimental procedures are needed to obtain data for risk assessment.
121Â citations
TL;DR: The currently available epidemiologic evidence from population studies of the health effects of atmospheric sulfur oxides and particulate matter is examined to approximate the exposure-response relationship linking pollutant concentrations with mortality and morbidity levels.
Abstract: Steadily rising energy costs have increased the need for reliable information on the health effects of atmospheric sulfur oxides and particulate matter. Because ethical and practical considerations limit studies of this question under controlled conditions, observational studies provide an important part of the relevant information. This paper examines the currently available epidemiologic evidence from population studies of the health effects of these pollutants. Nonexperimental studies also have important limitations, including the inability to measure accurately the exposure burden of free living individuals, and the potential for serious confounding by other factors affecting health. We begin with a discussion of some of these methodologic issues. The evidence is then reviewed, first in association with fluctuations in 24 hr mean concentration of sulfur oxides and particulate matter, and then in association with differences in mean annual concentration. In the last section, this evidence is summarized and used to approximate the exposure-response relationship linking pollutant concentrations with mortality and morbidity levels.
110Â citations
TL;DR: HAS most often affects males, peaks in the sixth and seventh decades of life and appears to occur more often in the industrialized Northeast and Midwest (although reporting artifact may be a factor).
Abstract: A nationwide survey of hepatic angiosarcoma (HAS) in the United States during the years 1964 through 1974 identified 168 cases. Of these, 42 cases (25%) were associated with known etiologic factors, such as vinyl chloride monomer exposure during preparation of poly(vinyl chloride), use of Thorotrast in angiography, exposure to inorganic arsenic, and treatment with androgenic-anabolic steroids; 126 cases (75%) are of uncertain etiology. HAS most often affects males (ratio of approximately 3:1), peaks in the sixth and seventh decades of life (somewhat earlier than other sarcomas of the liver) and appears to occur more often in the industrialized Northeast and Midwest (although reporting artifact may be a factor). There is an extraordinary relative risk for poly(vinyl chloride) polymerization workers; there may also be other chemical-industrial associations that require further investigation. Prospective epidemiologic studies of HAS should be considered as a means of identifying other causative factors (e.g., chemicals or drugs) related to HAS.
TL;DR: The meiotic pollen mother cells of Tradescantia (spiderwort) are highly synchronized in their prophase I and tetrad stages and Chromosomes of this stage are sensitive to physical or chemical mut...
Abstract: The meiotic pollen mother cells (PMC) of Tradescantia (spiderwort) are highly synchronized in their prophase I and tetrad stages. Chromosomes of this stage are sensitive to physical or chemical mutagens. Thus high frequency of acentric fragments or sticky chromosomes can be induced with very low level of mutagens. These induced chromosome aberrations become micronuclei (MCN) in the synchronized tetrads and they can be easily identified and scored. Based upon these features, the Tradescantia micronucleus bioassay was established. This bioassay involves the exposure of PMC in the young inflorescences of the plant cuttings to gaseous agents through diffusion, to liquid agent through absorption and dialysis from the stem to flower buds, or to radiation. The exposed samples are fixed in aceto-alcohol (1:3) and prepared into microslides by using the aceto-carmine squash method. Frequencies of MCN in a large population of synchronized tetrads are the indications of genetic damage caused by the agents. Mature pollen grains of Tradescantia are free cells which can be cultured in lactose-agar medium. The generative cells in the cultured pollen tubes can carry out mitosis similar to the in vivo condition. The G2 interphase chromosomes of pollen mitosis are highly sensitive to gaseous or liquid chemicals and radiation. Treatments can be applied to these mitotic generative cells of the mature pollen or the mitotic generative nuclei of the developing pollen tube. The mitotic chromosomes of the generative cells are allowed to proceed through mitosis in the culture medium and slides are prepared for metaphase figures. Frequencies of various types of chromatid aberrations can be scored and used as the indices of genetic damage.
TL;DR: Further research on these interactions as well as other possible interactions in metal carcinogenesis is needed, both in well defined in vitro systems and in relevant animal models.
Abstract: Metals constitute a fundamentally important part of the total human environment. Since human exposure often involves complex mixtures of metal compounds and, possibly, organic compounds which may be carcinogenic per se, interactions between these compounds may add significantly to human cancer risk. Our present knowledge about these kinds of interactions is very limited. The best investigated area is benzo(a)pyrene (BP)-metal oxide particle interactions in respiratory carcinogenesis in the hamster. Metal oxide particles were also shown to modify the carcinogenic effect of nitrosamines. Several reports describe experiments in which selenium compounds exerted a generally anticarcinogenic and antimutagenic activity. Inorganic arsenic compounds, which are accepted to be carcinogenic in man, have so far been negative in animal experiments except for one recent suggested report. Several authors have, however, suggested that these compounds may act as cocarcinogens due to their inhibition of DNA repair, although animal experiments to demonstrate a cocarcinogenic effect of arsenic compounds have been negative so far, except for one preliminary report. The concentration of zinc in the diet seemed to influence both transplanted tumor growth and the carcinogenicity of several organic compounds, and the possibility of a correlation between dietary zinc and certain cancer forms in man has been suggested. Protection against development of Leydigiomas usually induced by cadmium injection was afforded by simultaneous injection of zinc salts. Nickel carcinogenesis has been reported to be antagonized by manganese, and synergism between Ni and organic carcinogens, e.g. BP, has been demonstrated. There is no firm evidence that lead may be a cocarcinogen, although some limited experimental evidence is available. Oxidizing agents have been demonstrated to increase, and reducing agents to antagonize, the mutagenic effect of chromium compounds in vitro. The content of carcinogenic and other metals in asbestos has been suggested to modify the carcinogenic properties of asbestos. Since much of the information available at present is suggestive, further research on these interactions as well as other possible interactions in metal carcinogenesis is needed. Studies should be made both in well defined in vitro systems and in relevant animal models.
TL;DR: Clinical investigations have resulted in improved diagnosis, classification, and management of cancers of respiratory organs in nickel refinery workers, and mutagenicity tests of nickel compounds in bacterial systems have consistently been negative.
Abstract: Research on nickel carcinogenesis from 1975 to March 1980 is reviewed. Epidemiological studies have strengthened the evidence that workers in nickel refineries have increased risks of cancers of the nasal cavities and lungs. Clinical investigations have resulted in improved diagnosis, classification, and management of cancers of respiratory organs in nickel refinery workers. Carcinogenicity tests have demonstrated the carcinogenicity of nickel subsulfide (alpha-Ni3S2) in rodents following administration by a variety of parenteral routes. Radiotracer studies and x-ray diffractometry have clarified the metabolism of alpha-Ni3S2 in rodents. In vitro exposures of mammalian cells to certain nickel compounds have been shown to inhibit cellular uptake of thymidine-3H, and to induce chromosomal aberrations, somatic mutations, and morphological transformation. Mutagenicity tests of nickel compounds in bacterial systems have consistently been negative. Ni(II) has beeb reported to impair the fidelity of viral and bacterial DNA polymerases for in vitro replication of synthetic nucleotide templates.
TL;DR: A review of recent literature on epidemiology of prostatic cancer has revealed some basic facts, including that injections of large amounts of cadmium cause sarcoma at injection sites or testicular damage and eventually testicular tumors, and that Cadmium concentrations in testes and prostate increase during heavy exposure, and it has been shown that testosterone synthesis will decrease in cad mium-exposed animals.
Abstract: It has been shown in animal experiments that injections of large amounts of cadmium cause sarcoma at injection sites or testicular damage and eventually testicular tumors. Long-term exposure with s...
TL;DR: The wide variation of health effects found within the industry indicates the need for a standard protocol for future epidemiological studies, as well as for the development of suitable methodologies for experimental risk assessment.
Abstract: In most industrialized countries large numbers of workers are exposed to welding fumes. Although the general pattern of welders' health may not significantly differ from that of workers in other dusty industrial occupations which demonstrate elevated incidence of respiratory tract diseases with long latency periods, the extremely wide range of substances at potentially high concentrations produced by various welding technologies may give rise to undetected process-specific high-risk working conditions: ("hot spots"). The origin, prevalence and range of magnitude of such hot spots, especially for cancer of the respiratory tract, is discussed, with emphasis placed on the assessment of risk resulting from exposure to Cr(VI) and Ni accompanying the use of various technologies for the welding of stainless and high alloy steels. The wide variation of health effects found within the industry, however, indicates the need for a standard protocol for future epidemiological studies, as well as for the development of suitable methodologies for experimental risk assessment.
TL;DR: The Cornfield hockey-stick model is considered, and, for low-dose extrapolation, it is suggested that response be taken to be proportional to dose and to a power of time determined by background response.
Abstract: The main dose-response models for chronic toxicity are considered. For dichotomous response, the log probit, multi-hit, and multistage models are presented. For time-to-occurrence response, the log...
TL;DR: This paper reviews the following problems, sampling, decomposition procedures and most important analytical methods used for selenium determination, e.g., neutron activation analysis, atomic absorption spectrometry, gas-liquid chromatography, spectrophotometry, fluorimetry, and x-ray fluorescence.
Abstract: This paper reviews the following problems, sampling, decomposition procedures and most important analytical methods used for selenium determination, e.g., neutron activation analysis, atomic absorption spectrometry, gas-liquid chromatography, spectrophotometry, fluorimetry, and x-ray fluorescence. This review covers the literature mainly from 1975 to 1977.
TL;DR: Unlike the situation with organic compounds, metals do not show a high correlation between carcinogenicity and mutagenicity, but metals may act as comutagens by inhibiting the repair of damage to DNA caused by another agent.
Abstract: Unlike the situation with organic compounds, metals do not show a high correlation between carcinogenicity and mutagenicity. An agent may be mutagenic by causing misreplication of DNA due to alterations of the DNA template, decreased fidelity of DNA polymerase, or inhibition of the proofreading of DNA replication. In addition, bacteria have an inducible, error-prone DNA repair system (SOS repair) whose activity results in mutagenesis. In the best studied example of metal mutagenesis, chromate, there is little evidence for the involvement of the SOS system. Metals may act as comutagens by inhibiting the repair of damage to DNA caused by another agent. This has been demonstrated for arsenite. Comutagens would not be detected by standard screening methods.
TL;DR: Considering physical monitoring data of radiation dose in the air, internal exposure due to incorporation and concentration of man-made radioactive nuclides seems to be of a greater importance in increasing mutation incidence.
Abstract: Highly sensitive mutational responses of the stamen-hair system of some Tradescantia clones heterozygous for flower color (blue/pink, the blue being dominant) to low-level radiation and chemical mu...
TL;DR: It is hypothesized that the active molecular species is the cation and that metal induced mutations result from incorrect base-substitutions during DNA replication, supported by the observations that metal ions diminish the fidelity of DNA synthesis in vitro using a variety of DNA polymerases.
Abstract: A number of metals have been demonstrated to be mutagens in procaryotic and eucaryotic organisms as well as carcinogens in experimental animals. Epidemiologic studies have indicated that Ni, Cr, and As are involved in human carcinogenesis. We have hypothesized that the active molecular species is the cation and that metal induced mutations result from incorrect base-substitutions during DNA replication. This is supported by the observations that metal ions diminish the fidelity of DNA synthesis in vitro using a variety of DNA polymerases. There is a significant correlation between the metals that decrease fidelity and those that have been reported to be mutagenic and carcinogenic. Thus, metal carcinogens are no exception to the general postulate that carcinogens can be identified by their effects on DNA.
TL;DR: There exists sufficient evidence that heritable variation of the Ah locus occurs in man, and growing evidence indicates that persons with higher aryl hydrocarbon hydroxylase inducibility in their cultured mitogen-activated lymphocytes may have a statistically significantly increased risk for certain types of cancer and drug toxicity.
Abstract: The Ah locus represents a complex "cluster" of genese controlling the induction of numerous drug-metabolizing enzyme "activities" by polycyclic aromatic compounds. Allelic differences at the Ah loc...
TL;DR: Benzo(a)pyrene(BaP) originating from fossil fuel and other organic combustion processes is largely adsorbed on fine particulate and hence is a widespread atmospheric pollutant.
Abstract: Benzo(a)pyrene(BaP) originating from fossil fuel and other organic combustion processes is largely adsorbed on fine particulate and hence is a widespread atmospheric pollutant. Available emissions and air quality data are based on the total weight of particulate matter without reference to size and give little information on trends and concentrations of fine particulate BaP. Greater reliance on coal, synfuels and diesel fuel for energy production and transportation will significantly increase ambient levels of BaP. Because of the particulate size, BaP is substantially deposited in the lower lung and readily eluted into surrounding tissue. After elution in the lung, BaP is metabolically activated to its electrophilic, carcinogenic from by a complex enzyme system whose activity is increased by prior exposure to air pollutants, cigarette smoke and certain drugs. The resultant diol epoxide metabolite has been shown to bind covalently with the DNA of the lung. In experimental animals, BaP is a potent initiating carcinogen whose action is enhanced by sulfur dioxide, promoting agents and carrier fine particles. The effect of small, divided doses of BaP has been shown to be greater than that of a single high dose; no threshold has been established. Epidemiological studies show that mixtures containing BaP (such as urban air, industrial emissions and cigarette smoke) are carcinogenic and may interact synergistically. Occupational studies indicate that the action of BaP-containing mixtures is enhanced in the presence of SO2. However, quantitative risk assessment for BaP is precluded by problems in extrapolating to the general population from small-scale animal studies; uncertainties in findings of epidemiology; and imprecise exposure data. Existing stationary and mobile controls preferentially remove coarse particulate matter and are inefficient collectors of the particulate BaP. In the current absence of health and environmental standards for BaP, there is little incentive to control BaP emissions. BaP meets the criteria for regulation under the Clean Air Act; however, no such BaP standards have yet been proposed.
TL;DR: A number of physiological and pathological events perturb the deiodination pathway, leading to a decrease in T3 neogenesis and reciprocal changes in the circulating level of T3 and rT3 (which increases), the so-called "low T3 syndrome".
Abstract: Thyroxine, the major secretory product of the thyroid gland, is metabolized in the peripheral tissues by phenolic conjugation, deamination, decarboxylation, and a cascade of monodeiodinations. This...
TL;DR: Macrophage dysfunction may be an integral part of xenobiotic-induced immunosuppression and that the effector but not affector component of macrophage function may be the site of alteration.
Abstract: Immunomodulation by environmental chemical contaminants and the role immune parameters play in toxicity and risk assessment studies is of increasing concern. Although considerable evidence has indi...
TL;DR: The chelate effect is elucidated, and the relatively high stability of metal chelates in very dilute solutions is discussed, which is extended to explain the high stabilities of macrocyclic and cryptate complexes.
Abstract: The periodic distribution of known and suspected carcinogenic metal ions is described, and the chemical behavior of various types of metal ions is explained in terms of the general theory of hard and soft acids and bases. The chelate effect is elucidated, and the relatively high stability of metal chelates in very dilute solutions is discussed. The concepts employed for the chelate effect are extended to explain the high stabilities of macrocyclic and cryptate complexes. Procedures for the use of equilibrium data to determine the speciation of metal ions and complexes under varying solution conditions are described. Methods for assessing the interferences by hydrogen ion, competing metal ions, hydrolysis, and precipitation are explained, and are applied to systems containing iron(III) chelates of fourteen chelating agents designed for effective binding of the ferric ion. The donor groups available for the building up of multidentate ligands are presented, and the ways in which they may be combined to achieve high affinity and selectivity for certain types of metal ions are explained.
TL;DR: In vitro pollen germination appears to be a valuable method to examine the mutation types and physiological effects produced by a broad range of environmental pollutants and since in vitro germination is related to reproduction and gene transmission, the biological activity of these agents should be tested routinely.
Abstract: In vitro pollen germination was examined as a method to determine the mutagenic and physiological effects of environmental pollutants on higher organisms. Results were presented indicating that mut...
TL;DR: A series of overlapping recent human epidemiological studies have been suggestive of an increase in the incidence of lung cancer in populations occupationally exposed to beryllium, and argue for the strong presumption of a carcinogenic hazard to man in occupational bryllium exposures.
Abstract: Beryllium, some of its alloys, and a variety of its compounds have induced malignant tumors of the lung and osteogenic sarcoma in experimental animals. Three animal species, monkeys, rabbits, and rats, have been shown to be susceptible. Beryllium induces morphological transformation in mammalian cells and enhances viral transformation of mammalian cells. It has been shown to decrease fidelity of DNA synthesis. It has been recognized that exposure to compounds of this metal will, in some individuals, result in a chronic granulomatous disease of the lung. A series of overlapping recent human epidemiological studies have been suggestive of an increase in the incidence of lung cancer in populations occupationally exposed to beryllium. Such studies, together with animal and in vitro studies, argue for the strong presumption of a carcinogenic hazard to man in occupational beryllium exposures.
TL;DR: Ethanol with or without VC had a strong tumorigenic effect on the endocrine system and results indicate that ethanol is a cocarcinogen in relation to the carcinogen VC.
Abstract: Four treatment groups (80 male Sprague-Dawley rats/group) were used in a 2 X 2 factorial design: inhalation of 600 ppm vinyl chloride (VC) 4 hr/day, 5 days/week for 1 year; VC and ingestion of 5% e...
TL;DR: Ozone-sensitive and tolerant pollen populations have been identified in tobacco, petunia, and tomato cultivars, and Modified Brewbacker's growth medium is suitable for growth of both these pollen types.
Abstract: Sensitivity to ozone of pollen germinating in vitro is closely correlated with ozone sensitivity of the pollen parent. Ozone-sensitive and tolerant pollen populations have been identified in tobacco, petunia, and tomato cultivars. The rate of tube elongation can be reversibly slowed or stopped by exposure to low concentrations of ozone. Tube growth rates in the presence of a range of ozone dosages, of pollen populations exhibiting differing ozone sensitivity can be measured and different growth rates can be correlated with ozone dosages. The performance of selected pollen populations can then be used to bioassay ozone in ambient air by introducing the air sample into a growth chamber where ozone-sensitive pollen in growing. Petunia and tobacco pollen are especially useful because they store well at ordinary freezer temperatures and do not require special preparation prior to storage. Modified Brewbacker's growth medium is suitable for growth of both these pollen types. Four useful cultivars are Bel W-3, ozone-sensitive and Bel B, ozone-tolerant tobacco, and White Bountiful, ozone-sensitive and Blue Lagoon, ozone-tolerant petunia. Observations can be made directly by using a TV scanner, or by time lapse or interval photography. Year-round pollen production can be achieved in the greenhouse. Harvested pollen can be tested, packaged, and transported to user facilities without loss of vigor. Pollen populations are inexpensive to produce, respond reliably, and are simple to use as a bioassay for air quality.