Exposure to toxic metals

Various mechanisms have been developed by plants to alleviate stress imposed by exposure to toxic metal concentrations. Although the biochemical and molecular bases of adaptation and resistance of plant communities to high metal levels will be discussed extensively in Chapter 3, a survey summarising the possible anti-metal stress defence strategies and mechanisms forms an essential part of this chapter on toxicology. Every plant species, whether it is resistant or not to high metal concentrations, possesses defence responses against increased metal concentrations in the cell indeed. 

Diamond GL. 1988. Biological monitoring of urine for exposure to toxic metals. In Clarkson TW, Friberg L, Nordberg GF, et al., eds. Biological monitoring of toxic metals. New York, NY Plenum Press, 515-529. 

An intriguing problem about which we know very little is the mechanism of metal identification by the body that triggers Its response, as in the case of the huild-up of metallothioneins upon exposure to toxic metals. Perhaps the best understood of the metalloregulatory proteins is MerR that protects bacteria from mercurial toxicity. It is extremely sensitive to Hg, and distinguishes it from its congeners Zn and Cd. There is good evidence that the mercury receptor forms three-coordinate mercury(II) complexes (see Fig. 12.1c), making possible this specificity. ... 

Employees are frequently monitored when working in an environment where exposure to toxic metals is a possibility. The most common form of monitoring involves quantification of airborne concentrations of metals in the production process. Threshold limit values for airborne concentrations and time-interval exposure concentrations are defined by the U.S. National Institute for Occupational Safety and Health (NIOSH) to ensure worker safety. Workers may also be monitored by quantification of biological samples. The most common sample used is a random urine sample, and results are expressed in concentration units for the metal of interest per gram of creatinine to normalize for... 

The metals which give rise to clinical symptoms in man arc shown in Table I. Apart from the occasional suicide or murder attempt, most poisonings are due to environmenlal contamination or administration of drugs, remedies or cosmetics w hich contain metal sails. There are three main clinical effects of exposure to toxic metals. These are ... 

In most cases the replacement of lead products has been by products which offer lower exposure to toxic metals, limit the release of lead to the environment, are lighter, stronger or cheaper, or have new production methods. In the new millennium, lead-based products will consist only of lead products with a definite purpose. These product requirements will be ... 

Most avian studies emphasize ingestion as the primary route of exposure to toxic metals, because other routes of exposure are extremely uncommon. Because risk of exposure is greatly influenced by bird feeding and nesting habits, the characteristics of birds need to be taken into account for any study and its subsequent results. Age and sex differences in uptake and distribution of metals also influence metal exposure. Ultimately, even the same species of bird may behave differently in different environments, creating variations in risk of exposure (20). 

ICP-MS analysis has also heen of use in forensic cases where sanples have heen analysed to determine exposure to toxic metals, e.g. arsenic in supernatant of stomach contents. ... 

Exposure to arsine usually occurs in occupational settings that often involve concurrent exposures to other metal vapors and solvents. It is assumed that concurrent exposure with other chemicals, the toxicity of which targets the erythrocyte or renal function, would increase the severity of the response to arsine. 

Sauter, S., K.S. Buxton, K.J. Macek, and S.R. Petrocelli. 1976. Effects of exposure to heavy metals on selected freshwater fish. Toxicity of copper, cadmium, chromium and lead to eggs and fry of seven fish species. U.S. Environ. Protection Agen. Rep. 600/3-76-105. 75 pp. 

Although an essential nutrient metal at trace concentrations, selenium is highly toxic at moderate concentrations. Some of its compounds, such as hydrogen selenide, are very toxic. Exposure to Se metal fumes can cause severe irritation of eyes, nose and throat. The metal is listed by the US EPA as one of the priority pollutant metals in the environment. 

There are two reasons why artists are particularly vulnerable to diseases caused by exposure to toxic materials. First of all, artists, by the nature of their work, may have daily, long-term contact with materials that are highly toxic. Second, art materials are used as aerosols, powders, dusts, and in solution, from which maximum physical absorption and adsorption are possible. An artist can inhale aerosols. Powders and dusts are also inhaled and, in addition, can be absorbed through the skin. Solutions and many solvents evaporate into the air for the artist to inhale over long periods of time. This chemical assault, day after day, causes a variety of illnesses. In the following section on artists illnesses, all the chemicals cited are used by artists as they draw and paint, sculpt, work with metals, or develop and print photos—in general, as they engage in any art-associated activity. 

Cobalt is an essential element that is part of vitamin B12, or cobalamin, a coenzyme that is essential in the formation of proteins, nucleic acids, and red blood cells. Although cobalt poisoning is not common, excessive levels can be harmful. Most cases of human exposure to toxic levels of cobalt have occurred through inhalation in the workplace. Many exposures have been suffered by workers working with hard metal alloys of cobalt and tungsten carbide, where very fine particles... 

Heavy metals, like lead and mercury, have been recognized as toxic poisons for centuries. Further, toxic concentrations of mercury, for example, can trigger several effects like autoimmune diseases, infections, unexplained chronic fatigue, depression, nerve impairment, memory problems, decreased mental clarity, and bowel disorders. For several decades, mercury vapor exposure has caused severe health problems among chloralkali workers. This is only an example. It may be repeated that education can effectively minimize exposure to hazardous metals. Basic information and training for proper handling of toxic chemicals will reduce potential adverse health effects. 

Hair as a marker of exposure to toxicants has been of considerable interest to toxicologists for more than a hundred years. Casper reported in 1857 the analysis of hair for the detection of poisons in his famous Practisches Handbuch der gerichtlichen Median. He referred to Hoppe-Seyler, who had found arsenic in the hair of an 11-year-buried body and had discussed the possibility that the metal was incorporated before death. About 100 years later, the first report about the detection of an organic drug in hair was published. Goldblum et al. described an ultraviolet method to detect barbiturates in guinea pig hair. 

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