Observers do not participate in the final evaluation of the chemicals; this is the sole responsibility of the Task Force members. The efforts of all those who assisted in the preparation and finalization of the monograph are gratefully acknowledged.
Scope and purpose of the document
Definitions
Structural aspects of speciation
Similarly, elemental speciation at the macromolecular level has biological significance in physiology, biochemistry, and nutrition, but its importance in occupational or environmental toxicity is less well understood. On the other hand, valence state and inorganic and covalent organometallic speciation are of great importance in determining the toxicity of metals and semimetals.
Analytical techniques and methodology
In addition, plasma source time-of-flight mass spectrometry and glow discharge plasma can be used as tunable sources for elemental speciation. Calibration in elemental speciation analysis still remains a challenge, especially in the case of unknown species.
Bioaccessibility and bioavailability
Electrospray mass spectrometry and matrix-assisted laser desorption ionization mass spectrometry are ideal for obtaining structural information about the molecular species. Because of these competitive interactions, ion ratios often control the cellular uptake of toxic and nutrient elements.
Toxicokinetics and biomonitoring
The primary purpose of biological monitoring is to measure internal dose—that is, the amount of a chemical that is absorbed systemically. Measuring the internal body burden is of particular importance for metal species because of their tendency to accumulate.
Molecular and cellular mechanisms of metal toxicity Metals and semi-metals have multiple effects on biological
Health effects
According to the IUPAC recommendation (Templeton et al., 2000), a "chemical species" is "a specific form of an element defined as isotopic composition, electronic or oxidation state, and/or complex or molecular structure". In terms of risk assessment, this may be limited to forms of the element that have characteristic toxicity properties.
Isotopic composition
The above definitions of species and speciation suggest an organizing framework for understanding the species concept at different structural levels. In practice, an analysis of the speciation of a system should yield a set of species that are sufficiently different from each other to describe the system to the required level of detail.
Electronic and oxidation states
This temperature-dependent process has been used to assess long-term trends in climate (Remenda et al., 1994). Some bacteria possess a mercury reductase system that reduces HgII to volatile Hg0, which then diffuses out of the cell (Walsh et al., 1988; Misra, 1992).
Inorganic and organic compounds and complexes Organic and inorganic ligands affect the properties of metal
Maltol increases the absorption of aluminum in the gastrointestinal tract (Kruck & McLachlan, 1989) and allows it to cross the blood-brain barrier (Hewitt et al., 1991). On the other hand, some ligands such as histidine and cysteine reduce the bioavailability of NiII (Abbracchio et al., 1982).
Organometallic species
The blood-brain barrier refers to the functional barrier formed by the endothelium of blood vessels and the supporting tissues of the brain, which prevents certain substances from entering the brain from the blood. Mono- and dimethylmercury are strong neurotoxic agents that, unlike inorganic species, easily cross the blood-brain barrier.
Macromolecular compounds and complexes
Introduction
In addition to the risk of displacing the trace element that is noncovalently bound to the molecules, there is also the adverse effect of random trace element impurities being captured by the ligands of the matrix molecules during sample handling. In this regard, albumin, the main protein in human serum, is the most formidable scavenger of trace element impurities.
Sample collection and storage
This is particularly important in the case of CrIII/CrVI analysis in particulate air. As a rule of thumb, when no data are available from reliable studies by other research groups, the effect of sampling and storage conditions on the stability of the species in the matrix should be examined.
Sample preparation
In the case of tissue, the distribution of the trace elements can also be approached in a cytological way. Chemical speciation of the cytosol can be performed according to the procedure described in the next section.
Separation techniques
The derivatization of selenoamino acids, selenomethionine and organic arsenicals with a variety of reagents has also been reported (Bouyssiere et al., 2003). This is not obvious given the nature of the many reagents required to make GE work.
Sequential extraction schemes for the fractionation of sediments, soils, aerosols, and fly ash
The first prerequisite during the separation procedure is again the preservation of the elementary species. They are a useful approach to reveal possible environmental consequences of the presence of elemental species in, for example, land disposal of waste material, of sediments, etc.
Detection: elemental and molecular
The fact that many ion exchange chromatography elutions are not isocratic (i.e. the elution is performed under variable, usually increasing, ionic strength) requires special protocols to circumvent the problem of varying analyte response during the elution (Zhang & Zhang, 2003). Similar problems due to the influence of the eluent on the plasma can be expected and should be carefully considered, as mentioned in the previous section on ICP-AES.
Calibration in elemental speciation analysis
Adsorption on the walls of storage vessels, solvent composition, solvent evaporation, pH, oxidants, temperature, storage vessel material, air above the solution - all are parameters that compromise the stability of species in solution.
Direct speciation analysis of elements and particles The characterization of elemental species in particles, especially
A high-resolution scanning electron microscopy identification combined with energy-dispersive X-ray fluorescence spectrometry enables the study of the true nature of aerosol particles collected during metallurgical processes. They are used in environmental analysis (for example, the binding of actinides and fission products to humic acids and clay).
State of the art
Methods now routinely used are high-resolution scanning electron microscopy and electron probe microanalysis. For more information on speciation, the reader is referred to the literature cited in this chapter and to the European Virtual Institute for Speciation Analysis (http://www.speciation.net/).
Introduction
Bioaccessibility of elements in soils and sediments
The dominant role of sulfides in sediments in controlling the bioavailability of metal cations appears to be clear (Di Toro et al. Ankley et al., 1991). When the ratio of the sum of co-extracted metal elements to the concentration of acidic volatile sulfides exceeds 1.0 on a molar basis, toxic effects due to cations of the elements can be expressed if the cations are not complexed with other ligands.
Determinants of bioavailability
Uptake kinetics will vary with changes in chemical speciation (e.g. presence of water ions or hydroxide or chloride complexes). The binding rate is related to the concentration of the labile dissolved inorganic FeIII species [Fe(OH)2+.
Incorporation of bioaccessibility and bioavailability considerations in risk assessment
The concentration limitation method of Aldenberg & Slob (1991) and the No Risk Area approach of Van Assche et al. 1996) recognizes the importance and influence of bioavailability and bioavailability in the calculation of an environmental protection level. The biotic ligand model approach predicts toxicity by considering the chemistry of the exposure medium and the relationship between the exposure medium and the organism (the biotic ligand).
Introduction
Absorption
After exposure to the more soluble manganese (II) sulfate (MnSO4), less manganese was found in the lungs than after exposure to the less soluble manganese (II,III) tetroxide (Mn3O4) or manganese (II) phosphate (MnPO4), indicating more rapid pulmonary clearance of MnSO4 (Dorman et al., 2001a). A case of fatal dimethylmercury poisoning following dermal exposure has been reported (Smith, 1997; Toribara et al., 1997).
Disposition, excretion, and protein binding
Manganese enters the blood bound to transferrin in the trivalent state and to Į2-macroglobulin in the divalent state (Gibbons et al., 1976). Selenium is excreted in the urine in the form of monomethylated selenium (selenium sugar) when rats are fed a diet with selenium sources in an appropriate concentration (Suzuki & Ogra, 2002).
Biotransformation
The small part of lead in plasma and serum is in equilibrium with lead in soft tissue. The highest activity was detected in the testes, followed by the kidney, liver and lung (Vahter, 2002).
Exposure assessment and biological monitoring
Similarly, most of the studies in the epidemiological studies of nickel-induced cancer in the workplace rely on information about the process chemistry (IARC, 1990). In the last decade, attempts were made to introduce plasma lead determination to improve the biological monitoring of lead exposure, facilitated by the introduction of new analytical techniques such as ICP-MS (Smith et al., 1998).
Introduction
Mechanisms of DNA damage and repair
Important factors are the availability of free coordination sites, Ni2+/Ni3+ redox potential and charge of the complex (Muller et al., 1992). In a model system, chromate released guanine, whereas Cu2+ and Ni2+ released adenine (Schaaper et al., 1987).
Metal–protein interactions
Selenium serves as an interesting example of speciation of the element in the diet that affects the ultimate distribution of selenoproteins (see below). Permeability of the blood-brain barrier is proportional to Kow/(Mr)½ (where Mris molecular mass) up to about 400 daltons (Templeton, 1995).
Generation of reactive oxygen species
In rats, both dietary selenite and selenomethionine distribute plasma selenium into 50-60% selenoprotein P, 20-30% glutathione peroxidase, and 20-25% albumin (Whanger et al., 1994).
Effects on the immune system
Ni2+ inhibited proliferation in one clone when the intact complex was treated, but not when the antigen-presenting cell was treated with Ni2+ before exposure to the peptide (Romagnoli et al., 1991; Sinigaglia, 1994). Mice infected with either bacteria or virus were exposed to CdO by inhalation; mortality rates increased in the bacteria-infected mice and decreased in the viral-infected rodents.
Introduction
Acute toxicity
Respiratory distress syndrome in adults is also possible after ingestion of potassium dichromate (Iserson et al., 1983). Acute poisoning has also been reported from the nasal insertion of a potassium dichromate crystal (Andre et al., 1998).
Sensitization and irritation
A case of occupational asthma was reported in a worker exposed to palladium in an electroplating plant (Daenen et al., 1999). Neutral platinum compounds or salts without a halide ligand do not cause allergic reactions (Cleare et al., 1976).
Lung toxicity
With the mutual contact between cobalt metal and tungsten carbide particles, the reduction of oxygen in the environment with cobalt metal particles is catalyzed on the surface of the tungsten carbide particles. Compared to other metals (iron, nickel), metallic cobalt was the most active in the above reaction (Fenoglio et al., 2000).
Neurotoxicity
Prolonged intake of potassium permanganate (KMnO4) has also been implicated in the development of a similar syndrome (Holzgraefe et al., 1986). The clinical distal motor neuropathy manifesting as pulse drop is currently rare (Barats et al., 2000).
Nephrotoxicity
Cadmium-metallothionein is very efficiently taken up by the cells of the proximal tubules of the kidneys; depending on the concentration of cadmium–. When metallothionein synthesis was induced by pretreatment of animals with repeated low doses of CdCl2, the kidneys were protected against a nephrotoxic dose of cadmium-metallothionein (Jin et al., 1998).
Reproductive toxicity
These results suggest a redistribution of mercury to other tissues in neonates (Yoshida et al., 1987). HgII appears to accumulate in the placenta, thus limiting the amount reaching the fetus (Clarkson et al., 1972; . Khayat & Dencker, 1982).
Genotoxicity
Sparingly soluble cobalt (II) sulfide (CoS) was found to induce DNA strand breaks in Chinese hamster ovary cells (Robison et al., 1982). In vitro, CoCl2 has been shown to inhibit nucleotide excision repair after UV irradiation in human fibroblasts (Hartwig et al., 1991).
Carcinogenicity
DNA damage caused by reactive oxygen species may also result from a toxic and nonspecific inflammatory reaction caused by the accumulation of insoluble particles in the lung (Driscoll et al., 1994). Inhalation of Ni(CO)4 has been shown to induce some lung tumors in rats (Sunderman & Donnelly, 1965), and intravenous injections have resulted in an increase in the overall incidence of multi-organ neoplasms in rats (Lau et al., 1972). ).
