Lung clearance, translocation, and acute toxicity of arsenic, beryllium, cadmium, cobalt, lead, selenium, vanadium, and ytterbium oxides following deposition in rat lung

Pulmonary pathogenesis in a murine model of inhaled arsenical exposure

Arsenic trioxide (ATO), an inorganic arsenical, is a toxic environmental contaminant. It is also a widely used chemical with industrial and medicinal uses. Significant public health risk exists from its intentional or accidental exposure. The pulmonary pathology of acute high dose exposure is not well defined. We developed and characterized a murine model of a single inhaled exposure to ATO, which was evaluated 24 h post-exposure. ATO caused hypoxemia as demonstrated by arterial blood-gas measurements. ATO administration caused disruption of alveolar-capillary membrane as shown by increase in total protein and IgM in the bronchoalveolar lavage fluid (BALF) supernatant and an onset of pulmonary edema. BALF of ATO-exposed mice had increased HMGB1, a damage-associated molecular pattern (DAMP) molecule, and differential cell counts revealed increased neutrophils. BALF supernatant also showed an increase in protein levels of eotaxin/CCL-11 and MCP-3/CCL-7 and a reduction in IL-10, IL-19, IFN-γ, and IL-2. In the lung of ATO-exposed mice, increased protein levels of G-CSF, CXCL-5, and CCL-11 were noted. Increased mRNA levels of TNF-a, and CCL2 in ATO-challenged lungs further supported an inflammatory pathogenesis. Neutrophils were increased in the blood of ATO-exposed animals. Pulmonary function was also evaluated using flexiVent. Consistent with an acute lung injury phenotype, respiratory and lung elastance showed significant increase in ATO-exposed mice. PV loops showed a downward shift and a decrease in inspiratory capacity in the ATO mice. Flow-volume curves showed a decrease in FEV0.1 and FEF50. These results demonstrate that inhaled ATO leads to pulmonary damage and characteristic dysfunctions resembling ARDS in humans.

Human urinary and blood toxicokinetics of beryllium after accidental exposure

PURPOSE

Beryllium is known to have adverse health effects and is classified as carcinogenic to humans. However, data on systemic beryllium exposure in humans are rare and especially human toxicokinetics are largely uncharted. As such, the first reported multi-annual course of blood and urine concentrations after a high exposure scenario provides important new insights.

METHODS

For a medical follow-up biomonitoring samples were collected for 56 months from a male subject after an accidental and multi-faceted high exposure. Sampling started on day 2 post-exposure for urine and day 147 for blood. The samples were analyzed by inductively coupled mass spectrometry (ICP-MS) and plotted longitudinally as a function of time. Terminal half-lives were calculated assuming a first-order elimination process.

MAIN FINDINGS

Both matrices showed highly increased initial concentrations (about 100-fold), despite the 147-day delay in blood sampling, and a marked decline over time. In urine, a two-phase excretion process was suspected based on the longitudinal data. Calculations gave terminal half-lives of 117.5 days and 666.5 days for phases 1 and 2, respectively. Blood kinetics called for a terminal half-life of 103.5 days. Elimination kinetics in blood and urine were comparable, simultaneously gathered samples showed an excellent correlation (R² = 0.985).

PRINCIPAL CONCLUSIONS

The long-term follow-up after a high initial exposure to beryllium provides the first detailed insights into the elimination course of systemically available beryllium in humans. Conform kinetics of beryllium in urine and blood and the strong correlation between both parameters indicate high data validity and support the good representation of the current systemically available beryllium by urine and blood concentration in humans. The relatively long terminal half-lives in both matrices suggest a possible accumulation in humans in case of repeated exposures.

Enhanced activity of vanadia supported on microporous titania for the selective catalytic reduction of NO with NH3: Effect of promoters

Vanadium oxide-based catalysts are considered a promising catalyst for selective catalytic reduction (SCR) of NO with NH₃, which is an effective NO_x removal technology. As environmental issues have garnered more attention, however, improvements to vanadium-based SCR catalysts are strongly required. In a previous study, we found that vanadium oxide on microporous titania as a support (V/MPTiO₂) has certain advantages, such as improved thermal stability and more suppressed N₂O formation, over the use of conventional nanoparticle titania (DT-51) as a support. In this study, widely used promoters, such as W, Sb, and Mo, were added to V/MPTiO₂ to investigate whether they have promoting effects on V/MPTiO₂ as well. Among these promoters added catalysts, the W and Mo were found to have significant promoting effects on the enhancement of deNO_x activities at low temperatures, while the addition of Sb to V/MPTiO₂ tended to have a negative effect on the SCR activity. Based on the characterizations, including laser Raman, H₂-temperature programmed reduction (H₂-TPR), and in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) analysis, we found that the addition of W and Mo increased the degree of polymerization in V/MPTiO₂, which generated more reactive vanadia species. Hence, such changes, resulting from the addition of W and Mo promoters to V/MPTiO₂, yielded enhanced catalytic activity at low temperatures.

Bioaccessibility of potentially toxic elements in mine residue particles

Mining companies used to abandon tailing heaps in countryside regions of Mexico and other countries. Mine residues (MRs) contain a high concentration of potentially toxic elements (PTE). The wind can disperse dust particles (<100 μm) and once suspended in the atmosphere, can be ingested or inhaled; this is a common situation in arid climates. Nowadays, there is little information on the risk of exposure to PTEs from particulate matter dispersed by wind. The pseudo-total PTE in bulk and fractionated MR after aqua regia digestion, the inhalable bioaccessibility with Gamble solution (pH = 7.4), and the gastric bioaccessibility with 0.4 M glycine solution at pH 1.5 were determined. As and Pb chemical species were identified by X-ray absorption near-edge structure (XANES) spectroscopy. The highest rate of dispersion was observed with 74-100 μm particles (104 mg m-2 s-1); in contrast, particles <44 μm had the lowest rate (26 mg m-2 s-1). The highest pseudo-total As (35 961 mg kg-1), Pb (3326 mg kg-1), Cd (44 mg kg-1) and Zn (up to 4678 mg kg-1) concentration was in the <20 μm particles and As in the 50-74 μm (40 236 mg kg-1) particles. The highest concentration of inhaled bioaccessible As (343 mg kg-1) was observed in the <20 μm fraction and the gastric bioaccessible As was 744 mg kg-1, Pb was 1396 mg kg-1, Cd was 19.2 mg kg-1, and Zn was 2048 mg kg-1. The predominant chemical As species was arsenopyrite (92%), while 54% of Pb was in the adsorbed form. Erodible particle matter is a potential risk for humans in case of inhalation or ingestion.

The role of the non-ciliated bronchiolar cell in tolerance to inhaled vanadium of the bronchiolar epithelium

The Non-Ciliated Bronchiolar Cell (NCBC) is responsible for the defense and maintenance of the bronchiolar epithelium. Several cellular defense mechanisms have been associated with an increase in the secretion of CC16 and changes in the phenotype of the cell; these mechanisms could be linked to tolerance to the damage due to exposure to inhaled Particulate Matter (PM) of the epithelium. These defense mechanisms have not been sufficiently explored. In this article, we studied the response of the NCBC to inhaled vanadium, an element which adheres to PM. This response was measured by the changes in the phenotype of the NCBC and the secretion of CC16 in a mouse model. Mice were exposed in two phases to different vanadium concentrations; 1.27 mg/m³ in the first phase and 2.56 mg/m³ in the second phase. Mice were sacrificed on the 2nd, 4th, 5th, 6th and 8th weeks. In the second phase, we observed the following: sloughing of the NCBC, hyperplasia and small inflammatory foci remained without changes and that the expression of CC16 was higher in this phase than in phase I. We also observed a change in the phenotype with a slow decrease in both phases. The increase in the secretion of CC16 and the phenotype reversion could be due to the anti-inflammatory activity of CC16. The changes observed in the second phase could be attributed to the tolerance to inhaled vanadium.

Review of plant-vanadium physiological interactions, bioaccumulation, and bioremediation of vanadium-contaminated sites

Vanadium is a multivalent redox-sensitive metal that is widely distributed in the environment. Low levels of vanadium elevate plant height, root length, and biomass production due to enhanced chlorophyll biosynthesis, seed germination, essential element uptake, and nitrogen assimilation and utilization. However, high vanadium concentrations disrupt energy metabolism and matter cycling; inhibit key enzymes mediating energy production, protein synthesis, ion transportation, and other important physiological processes; and lead to growth retardation, root and shoot abnormalities, and even death of plants. The threshold level of toxicity is highly plant species-specific, and in most cases, the half maximal effective concentration (EC₅₀) of vanadium for plants grown under hydroponic conditions and in soil varies from 1 to 50 mg/L, and from 18 to 510 mg/kg, respectively. Plants such as Chinese green mustard, chickpea, and bunny cactus could accumulate high concentrations of vanadium in their tissues, and thus are suitable for decontaminating and reclaiming of vanadium-polluted soils on a large scale. Soil pH, organic matter, and the contents of iron and aluminum (hydr)oxides, phosphorus, calcium, and other coexisting elements affect the bioavailability, toxicity, and plant uptake of vanadium. Mediation of these conditions or properties in vanadium-contaminated soils could improve plant tolerance, accumulation, or exclusion, thereby enhancing phytoremediation efficiency. Phytoremediation with the assistance of soil amendments and microorganisms is a promising method for decontamination of vanadium polluted soils.

ICRP Publication 141: Occupational Intakes of Radionuclides: Part 4

The 2007 Recommendations (ICRP, 2007) introduced changes that affect the calculation of effective dose, and implied a revision of the dose coefficients for internal exposure, published previously in the Publication 30 series (ICRP, 1979a,b, 1980a, 1981, 1988) and Publication 68 (ICRP, 1994b). In addition, new data are now available that support an update of the radionuclide-specific information given in Publications 54 and 78 (ICRP, 1989a, 1997) for the design of monitoring programmes and retrospective assessment of occupational internal doses. Provision of new biokinetic models, dose coefficients, monitoring methods, and bioassay data was performed by Committee 2 and its task groups. A new series, the Occupational Intakes of Radionuclides (OIR) series, will replace the Publication 30 series and Publications 54, 68, and 78. OIR Part 1 (ICRP, 2015) describes the assessment of internal occupational exposure to radionuclides, biokinetic and dosimetric models, methods of individual and workplace monitoring, and general aspects of retrospective dose assessment. OIR Part 2 (ICRP, 2016), OIR Part 3 (ICRP, 2017), this current publication, and the final publication in the OIR series (OIR Part 5) provide data on individual elements and their radioisotopes, including information on chemical forms encountered in the workplace; a list of principal radioisotopes and their physical half-lives and decay modes; the parameter values of the reference biokinetic models; and data on monitoring techniques for the radioisotopes most commonly encountered in workplaces. Reviews of data on inhalation, ingestion, and systemic biokinetics are also provided for most of the elements. Dosimetric data provided in the printed publications of the OIR series include tables of committed effective dose per intake (Sv per Bq intake) for inhalation and ingestion, tables of committed effective dose per content (Sv per Bq measurement) for inhalation, and graphs of retention and excretion data per Bq intake for inhalation. These data are provided for all absorption types and for the most common isotope(s) of each element. The online electronic files that accompany the OIR series of publications contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions. Data are provided for inhalation, ingestion, and direct input to blood. This fourth publication in the OIR series provides the above data for the following elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), actinium (Ac), protactinium (Pa), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), and fermium (Fm).

Modulation of cytokines and chemokines expression by NAC in cadmium chloride treated human lung cells

Cadmium (Cd), is one of the most hazardous metals found in the environment. Cd exposure through inhalation has been linked to various diseases in lungs. It was shown that Cd induces proinflammatory cytokines through oxidative stress mechanism. In this report, we studied the immunomodulatory effect of a well known antioxidant, N-acetylcysteine (NAC) on cadmium chloride (CdCl2 ) treated human lung A549 cells through human cytokine array 6. The lung cells were treated with 0 or 75 µM CdCl2 alone, 2.5 mM NAC alone, or co-treated with 2.5 mM NAC and 75 µM CdCl2 for 24 h. The viability of cells was measured by crystal violet dye. The array results were validated by human IL-1alpha enzyme- linked immunosorbent assay (ELISA) kit. The viability of the 75 µM CdCl2 alone treated cells was decreased to 44.5%, while the viability of the co-treated cells with 2.5 mM NAC was increased to 84.1% in comparison with untreated cells. In the cell lysate of CdCl2 alone treated cells, 19 and 8 cytokines were up and down-regulated, while in the medium 15 and 3 cytokines were up and downregulated in comparison with the untreated cells. In the co-treated cells, all these cytokines expression was modulated by the NAC treatment. The IL-1α ELISA result showed the same pattern of cytokine expression as the cytokine array. This study clearly showed the modulatory effect of NAC on cytokines and chemokines expression in CdCl2- treated cells and suggests the use of NAC as protective agent against cadmium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1612-1619, 2016.

Toxic effects of selenium inhalation: acute damage of the respiratory system of mice

Accidental inhalation of selenium by humans has been associated with damage of respiratory tissues that is lacking a detailed histological definition. We have investigated the natural history of injury to the tracheal epithelium and lungs induced by a single intratracheal instillation of CD-1 mice with two different doses of dimethyl selenide (0.05 and 0.1 mg Se/kg of body weight). The animals were sacrificed 1, 7, 14, and 28 days after the single selenium treatment. Samples of the trachea and lungs were studied by light microscopy. The tracheal epithelium showed loss of cilia and acute necrosis that was followed by metaplastic transformation. Edema and diffuse alveolar damage was observed in the lungs. Our data suggest that: i) severity of respiratory lesions caused by selenium is dose dependent; ii) selenium causes transient metaplastic transformation of the tracheal epithelium; iii) chronic inflammation and increased thickness of alveolar septa occur in the lungs; iv) 4 weeks after selenium treatment, mice recover from the tracheal injury, whereas no amelioration of pulmonary lesions was observed.

Appropriate Exposure Routes and Doses in Studies Designed to Assess Developmental Toxicity: A Case Study of Inorganic Arsenic

Assessment of risks to human health from chemical agents is a complex process that requires the assembly, careful analysis, and integration of human and animal data collected from studies performed at different times, for disparate purposes, and under varying conditions. The application of risk assessment methods to data without consideration of the relevance of critical experimental parameters such as route of exposure or magnitude of dose can lead to specious determinations of the risk posed by exposure to environmental agents. A case study of the purported risk of developmental toxicity from inorganic arsenic is presented to illustrate (1) the nature of the problem, (2) how extant data from all studies are useful, (3) how appropriately designed modern studies can clarify the situation, and (4) how conflicted data should be evaluated in terms of appropriateness for use in risk assessment.

Selenium analogues of raloxifene as promising antiproliferative agents in treatment of breast cancer

Synthetic protocols for the preparation of selenium analogues of raloxifene were elaborated. General aim of the current research is to improve the positive impact of selenium atom introduction in drug design. Antiproliferative activity on CCL-8 (mouse sarcoma), MDA-MB-435s (human melanoma), MES-SA (human uterus sarcoma), MCF-7 (human breast adenocarcinoma), HT-1080 (human fibrosarcoma), MG-22A (mouse hepatoma) tumor cell lines, and normal cell line NIH 3T3 (mouse fibroblasts) was studied. Influence of aminoethoxy "tail" and benzoyl group position on SAR was discussed. Results of in vivo studies on BALB/c female mice with 4T1 cell induced breast cancer model showed that selenium analogue of raloxifene is able to suppress estrogen-depending tumor growth.

Occupational hazards and safety measures amongst the paint factory workers in lagos, Nigeria

Background

The manufacture of paint involves a variety of processes that present with medical hazards. Safety initiatives are hence introduced to limit hazard exposures and promote workplace safety. This aim of this study is to assess the use of available control measures/initiatives in selected paint factories in Lagos West Senatorial District, Nigeria.

Methods

A total of 400 randomly selected paint factory workers were involved in the study. A well-structured World Health Organization standard questionnaire was designed and distributed to the workers to elicit information on awareness to occupational hazards, use of personal protective devices, and commonly experienced adverse symptoms. Urine samples were obtained from 50 workers randomly selected from these 400 participants, and the concentrations of the heavy metals (lead, cadmium, arsenic, and chromium) were determined using atomic absorption spectroscopy.

Results

The results show that 72.5% of the respondents are aware of the hazards associated with their jobs; 30% have had formal training on hazards and safety measures; 40% do not use personal protective devices, and 90% of the respondents reported symptoms relating to hazard exposure. There was a statistically significant (p < 0.05) increase in the mean heavy metal concentrations in the urine samples obtained from paint factory workers as compared with nonfactory workers.

Conclusion

The need to develop effective frameworks that will initiate the integration and ensure implementation of safety regulations in paint factories is evident. Where these exist, there is a need to promote adherence to these practice guidelines.

Toxic elements in tobacco and in cigarette smoke: inflammation and sensitization

Biochemically and pathologically, there is strong evidence for both atopic and nonatopic airway sensitization, hyperresponsiveness, and inflammation as a consequence of exposure to tobacco mainstream or sidestream smoke particulate. There is growing evidence for the relation between exposure to mainstream and sidestream smoke and diseases resulting from reactive oxidant challenge and inflammation directly as a consequence of the combined activity of neutrophils, macrophages, dendritic cells, eosinophils, basophils, as a humoral immunological consequence of sensitization, and that the metal components of the particulate play a role in adjuvant effects. As an end consequence, carcinogenicity is a known outcome of chronic inflammation. Smokeless tobacco has been evaluated by the IARC as a group 1 carcinogen. Of the many harmful constituents in smokeless tobacco, oral tissue metallothionein gradients suggest that metals contribute to the toxicity from smokeless tobacco use and possibly sensitization. This work reviews and examines work on probable contributions of toxic metals from tobacco and smoke to pathology observed as a consequence of smoking and the use of smokeless tobacco.

Urinary levels, tissue concentrations and lung inflammation after nose-only exposure to three different chemical forms of beryllium

This study aimed to determine the toxicity and toxicokinetic of three Be chemical species A total of 120 mice (four groups of 30) were nose-only exposed. The first group was used as a control while the three others were exposed to 250 microg m(-3) of fine particles of three different Be species (Be metal, Be-F; Be oxide, BeO-F; Be aluminium, BeAl-F). Exposure lasted over three consecutive weeks, five days per week and 6 h per day. Blood and several tissues were collected one week after exposure. Urines were collected before the beginning of exposure, at the end of every week of exposure and one week after exposure. Results showed that urine concentrations were different from one Be species to another and that excretion continued after the end of exposure. Except for BeO-F, where Be urine concentrations were stable during the three weeks of exposure, concentrations of Be-F and BeAl-F reached a peak after the first week. According to particle size, BeO-F obtained the highest theoretical pulmonary deposition rate, which partially led to the highest Be lung concentration. This group also presented the lowest urine concentration but that did not lead to more severe lung inflammation. Moreover, even if BeAl-F obtained the lowest percentage theoretical pulmonary deposition, it showed the highest Be urinary concentration, the lowest Be lung concentration and the lowest lung toxicity. In this specific case, a high Be concentration in urine did not reflect a high exposure or a severe toxic effect.

Recent advances in understanding the biomolecular basis of chronic beryllium disease: a review

In this review we summarize the work conducted over the past decade that has advanced our knowledge of pulmonary diseases associated with exposure to beryllium that has provided a molecular-based understanding of the chemistry, immunopathology, and immunogenetics of beryllium toxicity. Beryllium is a strong and lightweight metal that generates and reflects neutrons, resists corrosion, is transparent to X-rays, and conducts electricity. Beryllium is one of the most toxic elements on the periodic table, eliciting in susceptible humans (a) an allergic immune response known as beryllium sensitization (BeS); (b) acute beryllium disease, an acutely toxic, pneumonitis-like lung condition resulting from exposure to high beryllium concentrations that are rarely seen in modern industry; and (c) chronic beryllium disease (CBD) following either high or very low levels of exposure. Because of its exceptional strength, stability, and heat-absorbing capability, beryllium is used in many important technologies in the modern world. In the early 1940s, beryllium was recognized as posing an occupational hazard in manufacturing and production settings. Although acute beryllium disease is now rare, beryllium is an insidious poison with a latent toxicity and the risk of developing CBD persists. Chronic beryllium disease-a systemic granulomatous lung disorder caused by a specific delayed immune response to beryllium within a few months to several decades after exposure-has been called the "unrecognized epidemic". Although not a disease in itself, BeS, the innate immune response to beryllium identified by an abnormal beryllium lymphocyte proliferation test result, is a population-based predictor of CBD. Genetic susceptibility to CBD is associated with alleles of the major histocompatibility gene, human leukocyte antigen DP (HLA-DP) containing glutamic acid at the 69th position of the beta chain (HLA-DPbeta-E69). Other genes are likely to be involved in the disease process, and research on this issue is in progress. The current Occupational Safety & Health Administration permissible exposure limit of 2 microg/m3 has failed to protect workers from BeS/CBD. As a safe exposure limit that will not lead to BeS or CBD has not yet been determined, the realization that the risk of CBD persists has led to a renaissance in research on the effects of the metal on human health. Current data support further reductions in exposure levels to help minimize the incidence of CBD. Steps that would directly impact both the power of epidemiologic studies and the cost of surveillance would be to develop and validate improved screening and diagnostic tests, and to identify more genetic factors that affect either sensitization or disease process. The major focus of this review is the recent research on the cellular and molecular basis of beryllium sensitization and disease, using a multidisciplinary approach of bioinorganic chemistry and immunology. First we present a historical background of beryllium exposure and disease, followed by occurrence of beryllium in the environment, toxicokinetics, biological effects, beryllium lung disease, and other human health effects.

Systemic imbalance of essential metals and cardiac gene expression in rats following acute pulmonary zinc exposure

It was recently demonstrated that particulate matter (PM) containing water-soluble zinc produces cardiac injury following pulmonary exposure. To investigate whether pulmonary zinc exposure produces systemic metal imbalance and direct cardiac effects, male Wistar Kyoto (WKY) rats (12-14 wk age) were intratracheally (IT) instilled with saline or 2 micromol/kg zinc sulfate. Temporal analysis was performed for systemic levels of essential metals (zinc, copper, and selenium), and induction of zinc transporter-2 (ZT-2) and metallothionein-1 (MT-1) mRNA in the lung, heart, and liver. Additionally, cardiac gene expression profile was evaluated using Affymetrix GeneChips (rat 230A) arrays to identify zinc-specific effects. Pulmonary zinc instillation produced an increase in plasma zinc to approximately 20% at 1 and 4 h postexposure with concomitant decline in the lung levels. At 24 and 48 h postexposure, zinc levels rose significantly (approximately 35%) in the liver. At these time points, plasma and liver levels of copper and selenium also increased significantly, suggesting systemic disturbance in essential metals. Zinc exposure was associated with marked induction of MT-1 and ZT-2 mRNA in lung, heart, and liver, suggesting systemic metal sequestration response. Given the functional role of zinc in hundreds of proteins, the gene expression profiles demonstrated changes that are expected based on its physiological role. Zinc exposure produced an increase in expression of kinases and inhibition of expression of phosphatases; up- or downregulation of genes involved in mitochondrial function; changes in calcium regulatory proteins suggestive of elevated intracellular free calcium and increases in sulfotransferases; upregulation of potassium channel genes; and changes in free radical-sensitive proteins. Some of these expression changes are reflective of a direct effect of zinc on myocardium following pulmonary exposure, which may result in impaired mitochondrial respiration, stimulated cell signaling, altered Ca2+ homeostasis, and increased transcription of sulfotransferases. Cardiotoxicity may be an outcome of acute zinc toxicosis and occupational exposures to metal fumes containing soluble zinc. Imbalance of systemic metal homeostasis as a result of pulmonary zinc exposure may underlie the cause of extrapulmonary effects.

The speciation of metals in mammals influences their toxicokinetics and toxicodynamics and therefore human health risk assessment

Chemical form (i.e., species) can influence metal toxicokinetics and toxicodynamics and should be considered to improve human health risk assessment. Factors that influence metal speciation (and examples) include: (1) carrier-mediated processes for specific metal species (arsenic, chromium, lead and manganese), (2) valence state (arsenic, chromium, manganese and mercury), (3) particle size (lead and manganese), (4) the nature of metal binding ligands (aluminum, arsenic, chromium, lead, and manganese), (5) whether the metal is an organic versus inorganic species (arsenic, lead, and mercury), and (6) biotransformation of metal species (aluminum, arsenic, chromium, lead, manganese and mercury). The influence of speciation on metal toxicokinetics and toxicodynamics in mammals, and therefore the adverse effects of metals, is reviewed to illustrate how the physicochemical characteristics of metals and their handling in the body (toxicokinetics) can influence toxicity (toxicodynamics). Generalizing from mercury, arsenic, lead, aluminum, chromium, and manganese, it is clear that metal speciation influences mammalian toxicity. Methods used in aquatic toxicology to predict the interaction among metal speciation, uptake, and toxicity are evaluated. A classification system is presented to show that the chemical nature of the metal can predict metal ion toxicokinetics and toxicodynamics. Essential metals, such as iron, are considered. These metals produce low oral toxicity under most exposure conditions but become toxic when biological processes that utilize or transport them are overwhelmed, or bypassed. Risk assessments for essential and nonessential metals should consider toxicokinetic and toxicodynamic factors in setting exposure standards. Because speciation can influence a metal's fate and toxicity, different exposure standards should be established for different metal species. Many examples are provided which consider metal essentiality and toxicity and that illustrate how consideration of metal speciation can improve the risk assessment process. More examples are available at a website established as a repository for summaries of the literature on how the speciation of metals affects their toxicokinetics.

Manganese dosimetry: species differences and implications for neurotoxicity

Manganese (Mn) is an essential mineral that is found at low levels in food, water, and the air. Under certain high-dose exposure conditions, elevations in tissue manganese levels can occur. Excessive manganese accumulation can result in adverse neurological, reproductive, and respiratory effects in both laboratory animals and humans. In humans, manganese-induced neurotoxicity (manganism) is the overriding concern since affected individuals develop a motor dysfunction syndrome that is recognized as a form of parkinsonism. This review primarily focuses on the essentiality and toxicity of manganese and considers contemporary studies evaluating manganese dosimetry and its transport across the blood-brain barrier, and its distribution within the central nervous system (CNS). These studies have dramatically improved our understanding of the health risks posed by manganese by determining exposure conditions that lead to increased concentrations of this metal within the CNS and other target organs. Most individuals are exposed to manganese by the oral and inhalation routes of exposure; however, parenteral injection and other routes of exposure are important. Interactions between manganese and iron and other divalent elements occur and impact the toxicokinetics of manganese, especially following oral exposure. The oxidation state and solubility of manganese also influence the absorption, distribution, metabolism, and elimination of manganese. Manganese disposition is influenced by the route of exposure. Rodent inhalation studies have shown that manganese deposited within the nose can undergo direct transport to the brain along the olfactory nerve. Species differences in manganese toxicokinetics and response are recognized with nonhuman primates replicating CNS effects observed in humans while rodents do not. Potentially susceptible populations, such as fetuses, neonates, individuals with compromised hepatic function, individuals with suboptimal manganese or iron intake, and those with other medical states (e.g., pre-parkinsonian state, aging), may have altered manganese metabolism and could be at greater risk for manganese toxicity.

Bérylliose Pulmonaire Chronique : un modèle d’interaction entre environnement et prédisposition génétique (1re partie)

INTRODUCTION

The physico-chemical properties of beryllium (Be) are crucial for high technology industries. The inhalation of beryllium may cause, in certain individuals, a specific sensitisation (BeS) and lead, in some of them, to a pulmonary granulomatosis called chronic pulmonary berylliosis (CPB).

BACKGROUND

Although there is no linear relationship between the level of exposure to Be and the risks of BeS and CPB, the highest exposures are associated with an increased risk. The specific influences of the chemical composition, the solubility and different types of Be on the risk of BeS an CPB are poorly understood. Insoluble particles of small diameter are probably associated with an increased risk. Many studies have reported the role of a genetic predisposition in the risk of BeS and CPB. At present the role of HLA-DPB1 Glu69 in sensitisation to Be is the best studied.

CONCLUSION

Sensitisation to Be and CPB result from the combination of exposure and predisposing genetic polymorphisms. CPB is a model for the understanding of the pathology of certain ideopathic pulmonary granulomatoses such as sarcoidosis.

In vivo distribution of arsenic after i.p. injection of arsonoliposomes in balb-c mice

We recently showed that arsonoliposomes (novel arsenic containg liposomes) demonstrate differential toxicity towards various types of cancer and normal cells, in cell culture studies, as well as anti-parasitic activity. In this study, the in-vivo distribution of the active moiety of these vesicles, As, is evaluated. Sonicated arsonoliposomes were prepared using the arsonolipid with palmitic acid acyl chain (C16) mixed with egg-phosphatidyl choline (PC) and cholesterol (Chol) [C16/PC/Chol at 8:12:10 mol/mol/mol]. A dose of arsonoliposomes, corresponding to 5 mg arsenate/kg was administered by intraperitoneal injection in balb-c mice. At various time points post-injection the mice were sacrificed and the distribution of As in the organs was measured, by atomic absorption spectroscopy. Results demonstrate that a high portion of the dose administered is rapidly excreted; since 1-h post-injection only about 30% of the dose administered was detected cumulatively in the animal tissues. After this the elimination of arsenic was a slow process with a total body elimination rate constant of 0.023 h(-1), corresponding to a half-life of 30 h. Tissues with the highest arsenic concentration during the study period are: spleen-kidneys-stomach, followed by lung, liver, intestines-heart, carcass+skin and finally blood. No acute toxicity, or effect on the body or organ weight of the mice was observed.

Cadmium accumulation and detoxification by alveolar macrophages of cigarette smokers

STUDY OBJECTIVES

Cadmium (Cd) is a toxic metal associated with emphysema and lung cancer, which is present in both air pollution and cigarette smoke. Metallothionein (MT) is an inducible protein that binds and detoxifies cellular Cd. The goals of this study were to determine whether increased concentrations of Cd are present in alveolar macrophages (AMs) of cigarette smokers (CSMs) and to determine whether MT accumulated in response to the presence of Cd.

DESIGN

AMs were recovered by BAL from 10 healthy nonsmokers (NSMs) and 10 CSMs. The Cd content of the AMs was determined by inductively coupled plasma-mass spectrometry, and the MT content was determined using a Cd/hemoglobin radioassay (with (109)Cd).

MEASUREMENTS

Cd was detected in AMs recovered from all subjects, with higher mean (+/- SEM) concentrations in CSMs compared with those in NSMs (3.4 +/- 0.5 vs 1.3 +/- 0.2 ng/10(6) cells; p < 0.005). There was a correlation between current smoking history (cigarettes per day) and the AM content of Cd (r = 0.74; p < 0.05). The mean AM content of MT was similar in NSMs (1.2 +/- 0.2 microg/10(7) cells) and CSMs (1.0 +/- 0.2 microg/10(7) cells).

CONCLUSIONS

AMs in CSMs accumulate significant amounts of Cd without a concurrent increase in MT content, indicating greater saturation of MT. Increased Cd burden in alveolar cells could contribute to the development of lung diseases in CSMs.

Bioaccumulation and locomotor effects of manganese phosphate/sulfate mixture in Sprague-Dawley rats following subchronic (90 days) inhalation exposure

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic manganese (Mn) compound added to unleaded gasoline in Canada. The primary combustion products of MMT are Mn phosphate, Mn sulfate, and a Mn phosphate/Mn sulfate mixture. Concerns have been raised that the combustion products of MMT containing Mn could be neurotoxic, even at low levels of exposure. The objective of this study is to investigate exposure-response relationships for bioaccumulation and locomotor effects following subchronic inhalation exposure to a mixture of manganese phosphates/sulfate mixture. A control group and three groups of 30 male Sprague-Dawley rats were exposed in inhalation chambers for a period of 13 weeks, 5 days per week, 6 h a day. Exposure concentrations were 3000, 300, and 30 microg/m(3). At the end of the exposure period, locomotor activity and resting time tests were conducted for 36 h using a computerized autotrack system. Rats were then euthanized by exsanguination and Mn concentrations in different tissues (liver, lung, testis, and kidney) and blood and brain (caudate putamen, globus pallidus, olfactory bulb, frontal cortex, and cerebellum) were determined by neutron activation analysis. Increased manganese concentrations were observed in blood, kidney, lung, testis, and in all brain sections in the highest exposure group. Mn in the lung and in the olfactory bulb were dose dependent. Our data indicate that the olfactory bulb accumulated more Mn than other brain regions following inhalation exposure. Locomotor activity was increased at 3000 microg/m(3), but no difference was observed in resting time among the exposed groups. At the end of the experiment, rats exposed to 300 and 3000 microg/m(3) exhibited significantly decreased body weight in comparison with the control group. Biochemical profiles also revealed some significant differences in certain parameters, specifically alkaline phospatase, urea, and chlorate.

Olfactory transport: a direct route of delivery of inhaled manganese phosphate to the rat brain

Experiments examining the dosimetry of inhaled manganese generally focus on pulmonary deposition and subsequent delivery of manganese in arterial blood to the brain. Growing evidence suggests that nasal deposition and transport along olfactory neurons represents another route by which inhaled manganese is delivered to certain regions of the rat brain. The purpose of this study was to evaluate the olfactory uptake and direct brain delivery of inhaled manganese phosphate ((54)MnHPO(4)). Male, 8-wk-old, CD rats with either both nostrils patent or the right nostril occluded underwent a single, 90-min, nose-only exposure to a (54)MnHPO(4) aerosol (0.39 mg (54)Mn/m(3); MMAD 1.68 microm, sigma(g) 1.42). The left and right sides of the nose, olfactory pathway, striatum, cerebellum, and rest of the brain were evaluated immediately after the end of the (54)MnHPO(4) exposure and at 1, 2, 4, 8, and 21 d postexposure with gamma spectrometry and autoradiography. Rats with two patent nostrils had equivalent (54)Mn concentrations on both sides of the nose, olfactory bulb, and striatum, while asymmetrical (54)Mn delivery occurred in rats with one occluded nostril. High levels of (54)Mn activity were observed in the olfactory bulb and tubercle on the same side (i.e., ipsilateral) to the open nostril within 1-2 d following (54)MnHPO(4) exposure, while brain and nose samples on the side ipsilateral to the nostril occlusion had negligible levels of (54)Mn activity. Our results demonstrate that the olfactory route contributes to (54)Mn delivery to the rat olfactory bulb and tubercle. However, this pathway does not significantly contribute to striatal (54)Mn concentrations following a single, short-term inhalation exposure to (54)MnHPO(4).

Influence of particle solubility on the delivery of inhaled manganese to the rat brain: manganese sulfate and manganese tetroxide pharmacokinetics following repeated (14-day) exposure

Dissolution rate can influence the pulmonary clearance of a metal and thus affect its delivery to the brain and other organs. The goal of this study was to determine the exposure-response relationship for the relatively soluble sulfate (MnSO(4)) and insoluble tetroxide (Mn(3)O(4)) forms of inhaled manganese in adult male CD rats. Rats were exposed 6 h/day for 7 days/week (14 exposures) to either MnSO(4) or Mn(3)O(4) at 0, 0.03, 0.3, or 3 mg Mn/m(3). End-of-exposure olfactory bulb, striatum, cerebellum, bile, lung, liver, femur, serum, and testes (n = 6 rats/concentration/chemical) manganese concentrations and whole-body (54)Mn elimination were then determined. Increased whole-body (54)Mn clearance rates were observed in animals from the high-dose (3 mg Mn/m(3)) MnSO(4) and Mn(3)O(4) exposure groups. Elevated manganese concentrations in the lung were observed following MnSO(4) and Mn(3)O(4) exposure to > or=0.3 mg Mn/m(3). Increased olfactory bulb and femur manganese concentrations were also observed following MnSO(4) exposure at > or=0.3 mg Mn/m(3). Elevated striatal, testes, liver, and bile manganese concentrations were observed following exposure to MnSO(4) at 3 mg Mn/m(3). Elevated olfactory bulb, striatal, femur, and bile manganese concentrations were observed following exposure to Mn(3)O(4) at 3 mg Mn/m(3). Animals exposed to MnSO(4) (3 mg Mn/m(3)) had lower lung and higher olfactory bulb and striatal manganese concentrations compared with levels achieved following similar Mn(3)O(4) exposures. Our results suggest that inhalation exposure to soluble forms of manganese results in higher brain manganese concentrations than those achieved following exposure to an insoluble form of manganese.

Pulmonary clearance of manganese phosphate, manganese sulfate, and manganese tetraoxide by CD rats following intratracheal instillation

Manganese (Mn) is ubiquitous in ambient air due to both industrial and crustal sources. It is also a component of the octane-enhancing fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT). The combustion of MMT by the automobile engine results in the formation of Mn particulates including phosphate, sulfate, and oxide forms. The objectives of this study were to determine the contribution of particle dissolution on pulmonary clearance rates of Mn sulfate (MnSO(4)), Mn phosphate, and Mn tetraoxide (Mn(3)O(4)) in CD rats following an intratracheal instillation exposure. In addition, brain (striatal) Mn concentrations were evaluated following exposure. Adult CD rats were intratracheally instilled with 0, 0.04, 0.08, or 0.16 microg Mn/g of either MnSO(4), Mn phosphate, or Mn(3)O(4). Rats were euthanized at 0, 1, 3, or 14 days after instillation. Lung and striatal Mn concentrations were measured by neutron activation analysis. Pulmonary clearance following single intratracheal instillation of MnSO(4), Mn phosphate, or Mn(3)O(4) was similar for each of the three compounds at each of the three doses used. All pulmonary clearance half-times were less than 0.5 day. At the concentrations used, striatal Mn levels were unaffected, and lung pathology was unremarkable. The dissolution rate constant of the Mn particles was determined in vitro using lung simulant fluids. The solubility of the Mn compounds was in general 20 to 40 times greater in Hatch artificial lung lining fluid than in Gamble lung simulant fluid. The dissolution rate constant of the water-soluble MnSO(4) particles in Hatch artificial lung fluid containing protein was 7.5 x 10(-4) g (Mn)/cm(2)/day, which was 54 times that of relatively water-insoluble Mn phosphate and 3600 times that of Mn(3)O(4). The dissolution rate constants for these compounds were sevenfold slower in Gamble lung fluid simulant. For both solutions, the time for half the material to go into solution differed only by factors of 1/83 to 1/17 to 1 for MnSO(4), Mn phosphate, and Mn(3)O(4), respectively, consistent with measured differences in size distribution, specific surface, and dissolution rate constant. These data suggest that dissolution mechanisms only played a role in the pulmonary clearance of MnSO(4), while nonabsorptive (e.g., mechanical transport) mechanisms predominate for the less soluble phosphate and oxide forms of Mn.

Appropriate use of animal models in the assessment of risk during prenatal development: an illustration using inorganic arsenic

BACKGROUND

Assessing risks to human development from chemical exposure typically requires integrating findings from laboratory animal and human studies.

METHODS

Using a case study approach, we present a program designed to assess the risk of the occurrence of malformations from inorganic arsenic exposure. We discuss how epidemiological data should be evaluated for quality and criteria for determining whether an association is causal. In this case study, adequate epidemiological data were not available for evaluating the potential effect of arsenic on development. Consequently, results from appropriately designed, conducted, and interpreted developmental toxicity studies, which have been shown to be predictive of human risk under numerous scenarios, were used. In our case study, the existing animal data were not designed appropriately to assess risk from environmental exposures, although such studies may be useful for hazard identification. Because the human and animal databases were deficient, a research program comprising modern guideline toxicological studies was designed and conducted.

RESULTS

The results of those studies in rats, mice, and rabbits indicate that oral and inhalational exposures to inorganic arsenic do not cause structural malformations, and inhalational exposures produced no developmental effects at all. The new study results are discussed in conjunction with considerations of metabolism, toxicokinetics, and maternal toxicity.

CONCLUSIONS

Based on the available experimental data, and absent contrary findings from adequately conducted epidemiological studies, we conclude that exposure to inorganic arsenic by environmentally relevant routes poses no risk of the occurrence of malformations and little risk of other prenatal developmental toxicity in developing humans without concomitant and near-lethal toxicological effects in mothers.

Vanadium

Vanadium is a steel-grey, corrosion-resistant metal, which exists in oxidation states ranging from -1 to +5. Metallic vanadium does not occur in nature, and the most common valence states are +3, +4, and +5. The pentavalent form (VO3-) predominates in extracellular body fluids whereas the quadrivalent form (VO+2) is the most common intracellular form. Because of its hardness and its ability to form alloys, vanadium (i.e., ferrovanadium) is a common component of hard steel alloys used in machines and tools. Although most foods contain low concentrations of vanadium (< 1 ng/g), food is the major source of exposure to vanadium for the general population. High air concentrations of vanadium occur in the occupation setting during boiler-cleaning operations as a result of the presence of vanadium oxides in the dust. The lungs absorb soluble vanadium compounds (V2O5) well, but the absorption of vanadium salts from the gastrointestinal tract is poor. The excretion of vanadium by the kidneys is rapid with a biological half-life of 20-40 hours in the urine. Vanadium is probably an essential trace element, but a vanadium-deficiency disease has not been identified in humans. The estimated daily intake of the US population ranges from 10-60 micrograms V. Vanadyl sulfate is a common supplement used to enhance weight training in athletes at doses up to 60 mg/d. In vitro and animal studies indicate that vanadate and other vanadium compounds increase glucose transport activity and improve glucose metabolism. In general, the toxicity of vanadium compounds is low. Pentavalent compounds are the most toxic and the toxicity of vanadium compounds usually increases as the valence increases. Most of the toxic effects of vanadium compounds result from local irritation of the eyes and upper respiratory tract rather than systemic toxicity. The only clearly documented effect of exposure to vanadium dust is upper respiratory tract irritation characterized by rhinitis, wheezing, nasal hemorrhage, conjunctivitis, cough, sore throat, and chest pain. Case studies have described the onset of asthma after heavy exposure to vanadium compounds, but clinical studies to date have not detected an increased prevalence of asthma in workers exposed to vanadium.

An acute intratracheal selenium study: immediate effects on respiration in guinea pigs

Pulmonary function was assessed in non-sensitized male guinea pigs (206-445 g) before and after intratracheal (ITr) treatment with saline or selenium (Se, 0.06 mg/100 g body weight) as selenium dioxide (SeO2) or seleno-L-methionine (SeM). Pulmonary functional parameters such as the respiratory rate (f), tidal volume (TV), dynamic lung compliance (Cdynl) and lung resistance (Rl) were determined using the respiratory flow (F) signal and the transpulmonary signal obtained via the intrapleural pressure (P) from the animal. Although, pulmonary dysfunction was observable with exposure to two different Se compounds, the SeO2-induced changes in f and Rl were significant (P < 0.05). Treatment with SeM did not result in alteration of any of the parameters significantly. Results indicated that acute ITr SeO2 exposure affects respiration precipitated by a significantly decreased f and an increased Rl unlike after SeM. The Cdynl did not change significantly after treatment with either of the two Se compounds. Comparing the immediate effects of the two different Se compounds on respiration, acute ITr SeO2 exposure was found to be more detrimental to pulmonary function than SeM.

Lung clearance of particles following excessive deposition of fly ash in golden hamsters

Male golden hamsters were exposed to coal fly ash (FA) at the concentration of 0 (control), 1, 2, or 20 mg/m3 for 3 or 6 months (20 hr/day, 7 days/week). They were sacrificed at 0, 1, 3 and 6 months after exposure to undergo morphological investigation of the lung clearance of particles ingested by alveolar macrophages (AMs) following excessive deposition of FA particles. Particle-laden AMs in a cluster decreased in inverse proportion to the dust burden after the cessation of exposure. AMs with well-spread lamellipodia frequently appeared on the degenerated AMs in a cluster. In addition, neutrophils also agglomerated mainly in the alveoli proximal to the terminal bronchioles and ingested a small amount of particles. These results suggest that AMs and neutrophils might recruit into alveoli enclosing AMs in necrosis and reingest released particles. Macrophages in bronchioles generally ingested fewer particles than those clustered in alveoli. This finding suggests that AMs ingesting a small amount of released particles could move on the mucociliary escalator of the terminal bronchioles. On the other hand, AMs ingesting a large amount of particles would agglomerate in alveoli due to the loss of their migrating ability. The latter agglomeration of particle-laden AMs might be responsible for the retardation of lung clearance in proportion to the lung burden of particles.

Mutagenicity, carcinogenicity and teratogenicity of vanadium compounds

The mutagenic, carcinogenic and teratogenic effects of vanadium and its compounds are reviewed. It is concluded that vanadium is not clastogenic and only weakly mutagenic; it has marked mitogenic activity affecting the distribution of chromosomes during mitosis and possibly causing aneuploidy. The few positive data on effects of vanadium during development leave it open whether direct effects on the embryo of fetus or physiological disturbances in the mother are responsible. No data exist indicating that vanadium is carcinogenic in animals or man, but since it interferes with mitosis and chromosome distribution, the possibility that vanadium might be carcinogenic under certain conditions cannot be dismissed offhand.

Cobalt in the environment and its toxicological implications

Cobalt is an essential trace element which is widely distributed in nature. Most of cobalt consumed is used in the manufacture of alloys, and although not released extensively in the environment, it may represent a hazard to human health. In addition, excess dietary cobalt produces toxic effects in animals. Polycythemia and hyperglycemia with transitory damage to pancreatic alpha-cells have been widely reported after cobalt administration. Cobalt salts induce respiratory deficiency in yeast. CoCl2 increased sister chromatid exchange (SCE) in P388D1 cells and in lymphocytes from two donors. So far it has not been possible to induce cancer in experimental animals using cobalt by any other route than by injection. Ingestion of cobalt may lead to reproductive changes in the male rat such as loss of testicular volume and darkening of testicle color. On the other hand, oral administration of cobalt did not produce teratogenicity or significant fetotoxicity in the rat at daily doses as high as 100 mg CoCl2/kg. However, cobalt affected the period of late gestation as well as the postnatal development of the pups. Occupational toxicology of cobalt, hygienic and epidemiologic aspects, and treatment of cobalt poisoning are also topics of special interest. Cobalt is a metal with marked allergenic potential. Asthma, interstitial lung disease and combined asthma and alveolitis have been described as occupational health hazards. EDTA, DTPA, and N-acetyl-L-cysteine have been suggested as possible antidotes in cobalt intoxication.

Persistence of vanadium compounds in lungs after intratracheal instillation in rats

Translocation and tissue distribution of two different forms of vanadium compounds, orthovanadate (soluble) and vanadium pentoxide (less soluble), were investigated. Groups of randomly selected rats were injected intratracheally with radiolabeled vanadium (48V) compounds and the animals were sacrificed at 1, 7 and 28 days after treatment. Blood, lungs and other major organs and tissues, namely liver, kidney, spleen, heart, testes, brain, muscle, and bone were sampled and the vanadium contents determined by gamma spectrometry. The less soluble form of vanadium (vanadium pentoxide) was eliminated from the lungs at a slow but exponentially linear rate, whereas the soluble form was translocated rapidly from this organ and exhibited a non-linear decline. Compared to the less soluble form, significantly less vanadium was retained in lungs 7 and 28 days after intratracheal instillation of vanadate. One day after treatment significantly higher concentrations (approximately 4 times) of vanadium after orthovanadate were observed in liver, kidney, spleen and bone compared to the pentoxide. However, tissue residues at 7 and 28 days indicated that both forms of vanadium were rapidly eliminated, except from bone and lungs. Results suggest a prolonged retention of less soluble forms of vanadium and possible health effects following repeated occupational exposure.

Feasibility of dose adjustment based on differences in long-term clearance rates of inhaled particulate matter in humans and laboratory animals

Long-term pulmonary clearance rates were evaluated for several laboratory animal species, dogs, and humans to determine if differences among species exist, and if so, the adequacy of the data for dose adjustment. Within each species, large variations in clearance rates were seen, probably as a result of differences in solubility of the aerosol particles, differences in measurement techniques, possible lung damage, transport to lung-associated lymph nodes, and binding of dissolved chemicals to cellular macromolecules in the lung. While few direct comparisons among species using the same aerosol were available, mechanical clearance of particles from the alveolar regions of dogs and humans was generally slower than in most laboratory species, with t1/2 values several-fold longer. Particle clearance rate variations of this magnitude were shown to induce potentially large differences in bioavailability. This can result in large errors in assessing human risk from animal studies unless a dose adjustment is made. It is suggested that despite limitations on available data, a two- to threefold adjustment of dose when extrapolating from small laboratory animals to humans, for quantitative risk assessment, should be considered, unless solubility half-times are very short.

Mutagenicity, carcinogenicity and teratogenicity of beryllium

The carcinogenicity of a number of beryllium compounds has been confirmed in experiments on laboratory animals and this metal has to be treated as a possible carcinogenic threat to man. These carcinogenic properties are associated with mutagenic activity as shown by the results of short-term tests performed in vitro with beryllium chloride and beryllium sulfate. These soluble beryllium compounds can produce some infidelity of in vitro synthesis, forward gene mutations in microorganisms and in mammalian cells. They are also able to induce cell transformation. In addition to the positive results obtained in several short-term assays beryllium compounds have been found to bind to nucleoproteins, to inhibit certain enzymes needed for DNA synthesis, to bind nucleic acids to cell membranes and to inhibit microtubule polymerization. The teratogenicity of beryllium salts is relatively unknown and needs additional investigation.