Polycyclic aromatic hydrocarbons natural sources

The next eight chapters will be devoted to the ecotoxicology of groups of compounds that have caused concern on account of their real or perceived environmental effects and have been studied both in the laboratory and in the field. These are predominantly compounds produced by humans. However, a few of them, for example, methyl mercury, methyl arsenic, and polycyclic aromatic hydrocarbons (PAHs), are also naturally occurring. In this latter case, there can be difficulty in distinguishing between human and natural sources of harmful chemicals. 

The largest releases of polycyclic aromatic hydrocarbons (PAHs) are due to the incomplete combustion of organic compounds during the course of industrial processes and other human activities. Important sources include the combustion of coal, crude oil, and natural gas for both industrial and domestic purposes, the use of such materials in industrial processes (e.g., the smelting of iron ore), the operation of the internal combustion engine, and the combustion of refuse (see Environmental Health Criteria 202, 1998). The release of crude oil into the sea by the offshore oil industry and the wreckage of oil tankers are important sources of PAH in certain areas. Forest hres, which may or may not be the consequence of human activity, are a signihcant... 

Some enviromnental agents are carcinogenic tobacco, coal tar, asbestos, alcohol, some polycyclic aromatic hydrocarbons. X-rays and other sources of radiation, and many natural products. 

Sources. B[major component of polynuclear aromatic hydrocarbons, also known as polycyclic aromatic hydrocarbons, and is usually bound to small particulate matter present in urban air, industrial and natural combustion emissions, and cigarette smoke. 

Polycyclic aromatic hydrocarbons (PAH), which are ubiquitous in the environment, including surface waters, undergo facile chlorination by hypochlorite when dissolved in humus-poor water to give a suite of chlorinated PAH (1660). It is therefore conceivable that this chlorination can occur under natural conditions, but this is yet to be determined. Another new possible source of natural chlorinated PAH is the reported in vitro reaction of benzo [a pyrene diol epoxide, the ultimate carcinogen of benzo aIpyrene with chloride ion to give chlorohydrin DDD, which has been isolated and identified as an intermediate en route to a benzol a pyrene-DN A adduct (1661). However, DDD is not considered to be a natural compound at this time. 

Polycyclic aromatic hydrocarbons (PAHs) are produced during the incomplete combustion of organic material. PAHs can also be produced through natural, non-combustion processes, and they may be present in uncombusted petroleum. Uncombusted petroleum can be a direct source to the waters of... 

Hydrocarbons, C Hy Smoke, gasoline fumes Cigarette smoke, industry Natural sources Contributes to photochemical smog Polycyclic aromatic hydrocarbons, lung cancer... 

Manoli, E. and C. Samara. 1999. Polycyclic aromatic hydrocarbons in natural waters Sources, occurrence and analysis. Trends Anal. Chem. 18 417 -28. 

Combustion processes of fossil fuels are currently the main source of energy generation. It is well known that, in these processes, pollutants -such as SO2, NOx and CO2 and CO-are emitted to the atmosphere. Organic emissions, whose harmful nature has become the cause of growing concern, are another important source of pollution released in these processes. In fact. Polycyclic Aromatic Hydrocarbons (PAH) have been widely studied and their carcinogenic and mutagenic potential has been a matter of considerable concern [1,2]. These emissions can be minimized by combustion optimization but not completely... 

McRae C., Snape C. E., Sun C. G., Fabbri D., Tartar D., Trombini C., and Fallick A. (2(X)0) Use of compound-specific stable isotope analysis to source anthropogenic natural gas-derived polycyclic aromatic hydrocarbons in lagoon sediments. Environ. Sci. Technol. 34, 4684-4686. 

Polycyclic aromatic hydrocarbons (PAHs) are considered as priority pollutants due to their mutagenic and carcinogenic properties. PAHs are introduced in the environment from natural sources [e.g., incomplete combustion of organic matter from natural processes (volcanic eruptions, fires)] or anthropogenic, such as burning of fossil fuels, waste incineration, traffic, and so forth. 

There are no known natural sources of the creosote mixture (IARC 1973). However, several of the PAH constituents of the mixture are known to have natural sources the reader is referred to the ATSDR Toxicological Profile for Polycyclic Aromatic Hydrocarbons (Agency for Toxic Substances and Disease Registry 1995) and the ATSDR Toxicological Profile for Cresols (Agency for Toxic Substances and Disease Registry 1992) for additional information on natural sources, releases, and levels of PAHs and cresols associated with creosote production, use, and disposal. 

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