AbstractWhile many terms are usually associated with suspended matter in the air, airborne particles or particulate matter (PM) generally refer to solid particles that may be composed of multiple phases (e.g., solids, liquid droplets, etc.). Airborne particles vary extensively in physical and chemical characteristics; their sizes can vary from tens of micrometers, that is, slightly smaller than beach sand or hair, to tens of nanometers. Solid airborne particles have been historically related to a wide range of occupational diseases such as various types of pneumoconioses (e.g., “black lung disease”), as well as less occupationally targeted respiratory illnesses such as acute respiratory irritation, asthma, or lung cancer. This chapter outlines airborne particles, its adverse health effects to workers in (1) areas with targeted production of particles and (2) in areas where exposure to ambient pollution is inevitable. This chapter presents metrics, techniques, exposure assessments, and biomarkers used for particulate measurements and routine monitoring. Also summarized in this chapter: its toxicity, mechanisms of attack, and carcinogenicity. Lastly, it tabulates existing standards both for the ambient and workplace and outlined some of the existing removal and control technologies. The ubiquity of airborne particles—from outdoor jobs, such as construction and firefighting, to indoor occupations, such as healthcare and custodial jobs, make it a central issue that is necessary to be addressed in any workplace area.
AbstractThis chapter is about a series of short‐chain per‐ and polyfluoroalkyl substances (PFAS). In the past, PFAS were described as fluorinated fatty acids or sulfonates. The overall structure of PFAS is a carbon chain with fluorine atoms substituting for hydrogen atoms. The resulting chemicals are chemically stable, water and oil resistant, and useful for many industrial applications, such as in the formation of polymers. The most notorious in this group are the fluorinated fatty acids (carboxylates) or sulfonates. In biological systems, these chemicals are generally well‐absorbed by the oral route and resistant to metabolism but also have the unusual property of having drastically different elimination kinetics between mammalian species.The available literature on this group of PFAS (C7 and below) is modest. This chapter will not attempt to review all this literature. Rather, human studies will be emphasized. Since human studies often suggest associations between PFAS exposure and health outcomes, these studies will be followed by definitive experimental animal studies that give insights into the human evidence. Afterward, a summary of attempts to estimate potential human risk by various international agencies will be described. What will become obvious, however, is that the overall uncertainty in the database of some of these chemicals has led to widely divergent risk assessment positions that need to be resolved. Risk management decisions on specific members of this class of chemistries are seen to be premature without such scientific resolution.
AbstractNaturally occurring ethers may be constituents of essential oils and may be extracted from these sources. Although some ethers may appear naturally, they may be prepared synthetically from other chemicals or other ethers.Symmetrical ethers are produced by the catalytic dehydration of their corresponding alcohols, for example, diethyl ether from ethanol. They are also obtained as by‐products from the formation of their corresponding esters or alcohols. Ethers may also be made by special synthesis procedures. Some ethers are obtained through the destructive distillation of selected hardwoods.Ethers have a wide variety of industrial uses. Their commercial value is recognized in the following industries: rubber, plastics, paints and coatings, refrigeration, medicine, dentistry, petroleum, chemical, perfume, cosmetics, toiletries, and food.The more volatile ethers have been used as liquid refrigerants, general anesthetics, commercial solvents, primers for gasoline engines, fuel additives, and rocket propellants. Other ethers have been used as alkylating agents in chemical syntheses of organic chemicals and in the manufacture of polymers. They are also used to denature alcohol. Halogenated ethers are used in the preparation of ion‐exchange resin, which is a modified polystyrene resin that is chloromethylated and then treated with a tertiary amine or with a polyamine. Ethers have wide use as commercial solvents and extractants for esters, gums, hydrocarbons, alkaloids, oils, resins, dyes, plastics, lacquers, and paints. They are used as dewaxing extractants for lubricating oils. Ethers have had limited use as cleaning and spotting agents. They are used as chemical intermediates in the manufacture of textile aids, such as dyes and resins. In the pharmaceutical industry, ethers are used as solvents, suspending agents, flavorings for oral drugs, and dental products. They are used to increase viscosity, as penetrants and wetting agents and as antioxidants and stabilizers. Ethers are used in foods as flavorings and in perfumes as fragrances. They are used as solvents for elastomers and for regenerating rubber. They have use as antiskinning agents in surface coatings and as weathering agents for paints and plastics. Ethers are also used in soaps. Ethers appear in heat transfer agents. Several industries use specific ethers for thickening, dispersing, suspending, binding, and film forming.The data presented here are arranged according to the chemical structure of the compounds. An effort has been made to place the chemicals within each group in an order that represents an increase in chain length. Even though the number of chemicals in any one group is limited, it is possible to make general, comparative statements. This corresponds with the acute toxicity data available in theNIOSH Registry of Toxic Effects of Chemical Substances.The oral toxicity and concentrated vapor data indicate that as the chain length increases in the symmetrical ethers, the toxicity is reduced. The inverse is true for skin penetration toxicity.
AbstractThe halogens are those elements in group XVII of the periodic table, and include fluorine, chlorine, bromine, iodine, and astatine, the latter of which is a radioactive element of no industrial importance. The physical properties of the halogens are described. They indicate an almost perfect doubling of atomic weights progressing from fluorine to bromine, paralleled by increases in specific gravity and melting and boiling points, and by decreases in water solubility.Chlorine and fluorine exist in the earth's crust in almost equal proportions (770 ppm for fluorine, 550 ppm for chlorine). The relative abundance of bromine and iodine are only about 2 and 0.04%, respectively, of that for chlorine. Seawater contains almost 19,000 ppm chlorine, compared to 65 ppm for bromine and less than 2 ppm for fluorine. Iodine exists only in trace quantities in seawater (about 0.05 ppm).Elements become progressively less electronegative and have less oxidizing potential as atomic weight increases. Each halogen forms an acid in water and combines with metals to form salts; the reactivity of these compounds shows the same relationship as the elemental halogens.Chemically, fluorine is the most powerful oxidizing agent known. It is the most reactive of all the elements. Free fluorine is rarely, if ever, found in nature. Elemental fluorine is produced on a commercial scale by electrolysis.Common operations where fluorine exposure occurs include the manufacture of fluorochemicals and plastics, rocket propellants, and fluorinated intermediates, metal production such as aluminum potroom work, the fluorination of pharmaceuticals and consumer products such as dentifrices, and the fluoridation of public drinking‐water supplies. Environmental contamination and air pollution with fluorine and fluorides may occur as a result of emissions from facilities for aluminum production, glass and ceramic manufacture, fertilizer manufacture, and the processing of fluorspar.Because of the reactivity of fluorine, exposures of humans and animals, and environmental contamination problems are almost always the result of fluorides, rather than fluorine gas. Most studies of fluorine itself are artificial and of academic rather than practical interest. Functionally, acute exposures to fluorine gas must be regarded as severe and potentially lethal corrosive exposures, with the added nuances of disturbances in calcium metabolism because of the reaction between the calcium ion and the fluoride ion.Chlorine is associated with the largest array of industrially useful compounds of all the halogens; it is the ninth highest volume chemical produced in the United States. Chemically, chlorine is more reactive than either bromine or iodine; it displaces bromine and iodine from their salts and enters into substitution and addition reactions with both inorganic and organic substances. When moist, but not when dry, chlorine unites directly with most elements. The physical properties of chlorine are given. Recognition of widespread environmental contamination problems associated with persistent chlorinated organic compounds has led to pressure to reduce the use of chlorinated compounds in industrial chemicals. The outcome of this concern is unclear at this time, but it is likely to lead to substitution of other compounds for those containing environmentally persistent and toxic chlorinated materials. Although most of the identified compounds that present environmental contamination problems are higher molecular weight organic compounds, the use of chlorinated solvents in cleaning and degreasing operations has already been reduced and will be further reduced because of their impact on the ozone layer. Higher molecular weight organic compounds containing chlorine have been identified as possible xenoestrogens. The concern of the scientific community is high, and much research is under way to clarify the role of halogenated xenoestrogens in biological systems. It is likely that if the halogenated organic compounds are confirmed to be biologically detrimental, there will be a further reduction in the production and use of these compounds. The introduction of chemically reactive inorganic halogens, principally chlorinated compounds, into the environment in groundwater and air may lead to active halogenation of natural products to xenoestrogens. If this pathway is confirmed, this, too, will lead to a reduction in the use of chlorinated compounds.Chlorine is noncombustible in air but will support the combustion of other materials. It reacts explosively or forms explosive mixtures with many common materials, including acetylene, turpentine, ammonia gas, fuel gas, hydrocarbons, hydrogen, and finely divided metals. Chlorine may also combine with water or steam to produce hydrogen chloride (HCl) fume.The reactivity of bromine lies between that of chlorine and iodine. Bromine will cause ignition of organic materials, including wood, cotton, and straw. It reacts violently on contact with natural rubber and reacts explosively with a number of common substances, including aldehydes, ketones, carboxylic acids, acetylene, acrylonitrile, ammonia, ethyl phosphine, hydrogen, nickel carbonyl, ozone, oxygen difluoride, phosphorus, potassium, sodium, and sodium carbide. Because of its explosive potential, facilities where bromine is manufactured or used should be designed to dispose rapidly of liquid bromine spills.Although it is estimated that 1015–1016 tons of bromine are contained in the earth's crust, it is widely distributed and found only in low concentrations in the form of bromide salts. The most readily recoverable form of bromine occurs as soluble salts in salt lakes, inland seas, brine wells such as those in Michigan and Arkansas, and seawater. Today, little bromine is extracted from seawater, which contains bromide salts in a concentration of only 65 ppm. The largest single current use of bromine is for the production of fire retardants.Agricultural chemical production consumed about 10% of bromine production, primarily as methyl bromide. However, recent restrictions on the use of brominated pesticides, such as ethylene dibromide and DBCP and proposed limitations on such fumigants as methyl bromide are expected to further reduce the use of these brominated chemicals in the future.Skin or eye contact with vapor or liquid bromine pentafluoride causes painful, deep‐seated, long‐lasting burns. The acute effect of this substance on the lung is similar to that of phosgene.Iodine is the 47th most abundant element in the earth's crust. The name iodine derives from the Greek word for violet‐colored,ioeides, which was used to describe the purple vapor generated by heating iodine. It is the heaviest of the halogens that are of industrial interest. Under ordinary conditions, iodine takes the form of gray‐black plates or granules that have a metallic, crystalline luster. It volatilizes at room temperature to yield a sublimed, violet vapor. Iodine's physical properties are shown.Although iodine resembles other members of the halogen group, it is the least electronegative; it is thus the least chemically reactive of the halogens and forms the weakest bonds with more electropositive elements.Iodine is used both in animal and human medicine, where its disinfectant and antiseptic properties are valued. The lack of iodine causes goiter (compensatory hypertrophy of the thyroid gland), and iodine is used both to treat iodine deficiency and hyperthyroidism. Principal iodine compounds and their industrial uses are shown.The inorganic iodine compounds of commercial interest, and their physical properties, are discussed. The iodides, an important class of inorganic iodine compounds, have less tendency to form complexes than the other halides. Chlorine and bromine freely displace iodine from the iodides. Iodine forms industrially useful and important compounds with hydrogen, metals, the other halogens, and oxygen. Those presented here are typical.
AbstractOrganic peroxides (ROOR′), solid or liquid with the bivalent OO structure. Relatively unstable and highly reactive molecules due to the presence of an oxygen–oxygen linkage. The oxygen–oxygen bond may be cleaved to form highly reactive free radicals and react with many substances (e.g., metals, acids, and bases). ROORs are used in plastics, rubbers, and many industries as initiators, accelerators, promoters, catalysts, activators, and more. Major concerns with ROORs are associated with fires, explosions, and corrosiveness. Reactive oxygen species and free radicals may lead to DNA damage and mutagenesis. Recent work from government agents, academic research laboratories, and manufacturing organizations have focused on physical hazards classification and categorization; and producing best practice protocols for safe handling and storage, control of temperatures, self‐accelerating decomposition temperatures, spills cleaning, disposal, and treatment of ROORs residues. These efforts allow compliance with countries and international regulations. Potential health hazards are associated with eye and skin contact, inhalation, and ingestion. Acute exposure may lead to irritation, allergic response, and potential damage to the eye and skin. As with any irritant or corrosive, dose is a critical consideration with respect to understanding the risk. Chronic exposures, mostly understood in animals but there are human data, can cause a myriad of effects. These may range from respiratory illnesses, to liver, kidney damage, and cancer. The manufacturer's SDS of individual chemical may provide toxicity information. This chapter summarizes chemical‐specific toxicity information on 77 organic peroxide compounds grouped in eight physical hazard categories. NIOSH has fully validated the method for benzoyl peroxide. NTP has released a report on the toxic effects oft‐butyl perbenzoate and it deserves to be considered. Exposure assessment methods when available were presented. Future research needs to focus on epidemiological and toxicological studies of ROORs.
