Most of the chlorinated hydrocarbons, benzene, other aromatic hydrocarbons, some metals, carbon monoxide, and cyanides, among others, produce one or more effects in target organs. Such an effect may be the most probable result of exposure to the particular chemical. Although this chapter does not include specific sections on liver, kidney, lung, or blood toxins, many of the LCSSs mention those effects in the toxicology section. Corrosive substances are those that cause destruction of living tissue by chemical action at the site of contact and are solids, liquids, or gases.
Frequency of exposure also has an important influence on the nature and extent of toxicity. The total amount of a chemical required to produce a toxic effect is generally less for a single exposure than for intermittent or repeated exposures because many chemicals are eliminated from the body over time, because injuries are often repaired, and because tissues may adapt in response to repeated low-dose exposures. Some toxic effects occur only after long-term exposure because sufficient amounts of chemical cannot be attained in the tissue by a single exposure.
Initial monitoring should be performed and repeated any time that there is a change in the use of formalin, which may result in an increase in exposure. Risk Management Issues All fresh specimens should be handled carefully, since each specimen represents a potential source of infectious material. Standard safety precautions, including the use of personal protective equipment, the use of a biological safety cabinet when working with infectious materials, and proper handling of chemicals, should be followed (7, 53-56). Material safety data sheets (MSDS) should be reviewed for all reagents used in the laboratory.
For many years, sulfuric acid-dichromate mixtures were used to clean glassware. These solutions are corrosive and toxic and present difficulties for disposal. Their use should be avoided if at all possible. A common substitute is a sulfuric acid-peroxydisulfate solution, and commercial cleaning solutions that contain no chromium are readily available.
Single-dose exposures higher than 500 rem are probably fatal. A single dose of ~100 rem may cause a person to experience nausea or skin reddening, although recovery is likely. However, if these doses are cumulative over a period of time rather than a single dose, the effects are less severe. Long-term effects, which develop years after a high-dose exposure, are primarily cancer.
Once sensitization occurs, allergic reactions result from exposure to extremely low doses of the chemical. Some allergic reactions are immediate, occurring within a few minutes after exposure. Anaphylactic shock is a severe immediate allergic reaction that results in death if not treated quickly.
Owing to the different nature of heavy metals, extracting solutions that can optimally remove them must be carefully sought during soil washing. Several classes of chemicals used for soil washing include surfactants, cosolvents, cyclodextrins, chelating agents, and organic acids [101-106]. All these soil washing extractants have been developed on a case-by-case basis depending on the contaminant type at a particular site.
Sittig’s Handbook of Toxic and Hazardous Chemicals and Carcinogens, 5th edition, two volumes (Pohanish, 2008). This very good reference, which is written with the industrial hygienists and first responder in mind, covers 2,100 substances. Bretherick’s Handbook of Reactive Chemical Hazards, 7th edition (Urben, 2007). This handbook is a comprehensive compilation of examples of violent reactions, fires, and explosions due to unstable chemicals, as well as reports on known incompatibility between reactive chemicals. The format, organization, and contents of LCSSs are described in detail in the introduction on the CD.
Microbial adaptation to acids
With fixed centralized facilities, contaminated soil is brought to the plant, whereas with mobile/transportable facilities, the plant is transported to a contaminated site, and soil is processed on the site. Where mobile/transportable plant is used, the cost of mobilization and demobilization can be significant. However, where large volumes of soil are to be treated, this cost can be more than offset by reusing clean material on the site (therefore avoiding the cost of transport to an off-site centralized treatment facility, and avoiding the cost of importing clean fill). In this paper, scattered literature is utilized to review the possible sources of contamination, basic chemistry, and the associated environmental and health risks of priority heavy metals (Pb, Cr, As, Zn, Cd, Cu, Hg, and Ni) which can provide insight into heavy metal speciation, bioavailability, and hence selection of appropriate remedial options.
However, storage of commercially obtained chemicals (e.g., in 500-g jars or 1-L bottles) should be carefully managed from the standpoint of chemical compatibility. Accidental contact of incompatible substances results in a serious explosion or the formation of substances that are highly toxic or flammable or both. Although trained laboratory personnel question the necessity of following storage compatibility guidelines, the reasons for such guidelines are obvious after reading descriptions of laboratories following California earthquakes in recent decades [see Pine (1994)].
Delayed allergic reactions take hours or even days to develop, the skin is the usual site of such delayed reactions, becoming red, swollen, and itchy. Delayed chemical allergy occurs even after the chemical has been removed; contact with poison ivy is a familiar example of an exposure that causes a delayed allergic reaction due to uroshiol. Also, just as people vary widely in their susceptibility to sensitization by environmental allergens such as dust and pollen, individuals also exhibit wide differences in their sensitivity to laboratory chemicals.