Naturally occurring chemical substances

Since some chemicals substances described by this exclusion can be manufactured both under the terms of the exclusion and by other means, the applicability of this exclusion is determined by how the substance was actually manufactured. A person required to report for the lUR must report a chemical substance that it manufactures by other means, even if the chemical substance could have also been produced in a manner described in this exemption. Any chemical substance produced from an exempt naturally occurring chemical substance is reportable unless it is otherwise excluded.  

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Workers come in contact with a large number of chemical substances in work areas, as does the general public. The commonly found chemical carcinogens are grouped under (1) polycyclic aromatic hydrocarbons (PAHs), (2) nitroso compounds, (3) halogenated hydrocarbons (solvents e.g., carbon tetrachloride, chloroform, trichloroethylene, and methylene chloride), (4) inorganic metals and minerals (beryllium, cadmium, nickel, cobalt, chromium, asbestos and arsenic), and (5) naturally occurring chemical substances (aflatoxins). 

Edible and nonedible plants contain numerous naturally occurring chemical substances that can be toxic if exposures are excessive. Many of these chemicals act as natural pesticides that help protect the plant from insects and other predators. As far as the edible plants are concerned, eating a varied diet containing fresh fruits and vegetables with beneficial properties usually avoids significant risks of poisoning by naturally occurring plant toxins. 

I have included in today s presentation three of these issues first, the distinction between a "new" and a "naturally occurring" chemical substances for the purpose of the applicability of the premanufacture notification (PMN) requirement of TSCA second, the scope of the research and development exemption from the PMN requirements, and its implication for open field testing of microorganisms and third the type and amount of information that EPA might need for risk/benefit analyses of new microorganisms. I will also briefly mention some technical areas in which further research would greatly facilitate the processes of risk/benefit assessment. 

El.l Naturally occurring chemical substances are in general diamagnetic, (a) Which of the substances CO, NO, CO2, and NO2 might be paramagnetic (NO is a special case, see Chapter 6.) (b) Can any of the hydrocarbon species shown below be paramagnetic Can ions of the species be paramagnetic ... 

Chemicals are ubiquitous as air, carbohydrates, enzymes, lipids, minerals, proteins, vitamins, water, and wood. Naturally occurring chemicals are supplemented by man-made substances. There are about 70000 chemicals in use with another 500-1000 added each year. Their properties have been harnessed to enhance the quality of life, e.g. cosmetics, detergents, energy fuels, explosives, fertilizers, foods and drinks, glass, metals, paints, paper, pesticides, pharmaceuticals, plastics, rubber, solvents, textiles thus chemicals are found in virtually all workplaces. Besides the benefits, chemicals also pose dangers to man and the environment. For example ... 

Bioconversion Chemical conversion of a naturally occurring biodegradable substance using a biocatalyst. 

As a starting point, the book reviews the general properties of the raw materials. This is followed by the different techniques used to convert these raw materials to the intermediates, which are further reacted to produce the petrochemicals. The first chapter deals with the composition and the treatment techniques of natural gas. It also reviews the properties, composition, and classification of various crude oils. Properties of some naturally occurring carbonaceous substances such as coal and tar sand are briefly noted at the end of the chapter. These materials are targeted as future energy and chemical sources when oil and natural gas are depleted. Chapter 2 summarizes the important properties of hydrocarbon intermediates and petroleum fractions obtained from natural gas and crude oils. 

They are added for specific purposes (e.g. to preserve or sweeten food). Growing pressure to use natural substances to meet such needs has led to surprisingly little discussion about the relative safety of naturally-occurring substitutes as opposed to synthetic additives. For example, although synthetic additives should be more easy to produce in purified form, naturally-occurring chemicals may be more acceptable to some members of the public. 

Figure 1.2. Scheele isolated a family of naturally occurring sour substances. Subsequently, the elemental composition of each substance was determined using Lavoisier s combustion method and later the different structures were proposed. Each member contains common structural element, a carboxylic acid group which gives each its sour taste. The two-dimensional representation of chemical structures as shown is convenient but can be misleading. Also shown is the structure of urea, the first naturally occurring substance to be made in the laboratory by Wohler (shown), who provided the first experimental challenge to the concept of vitalism.

MINERALOGY. The science of mineralogy is concerned with the formation, occurrence, properties, composition, and classification of minerals. Vnrinus definitions of a mineral have been proposed. Possibly, the most acceptable may be. "a naturally occurring inorganic substance, usually crystalline, possessing a relatively definite chemical composition and physical characteristics. It should be pointed out that some naturally formed organic substances, particularly of an economic resource nature, are sometimes classified as minerals. 

Bate-Smith, E.C., and Westall, R.G., Chromatographic behavior and chemical structure (I) naturally occurring phenolic substances, Biochem. Biophys. Acta, 4, 427, 1950 Chem. Abs., 44, 5677a, 1950. 

Chevolot, L., Cochard, J.C., and Yvin, J.C., Chemical induction of larval metamorphosis of Pecten maximus with a note on the nature of naturally occurring triggering substances, Mar. Ecol. Prog. Ser., 74, 83, 1991. 

Mineral— A naturally occurring solid substance of nonbiological origin, having definite chemical composition and crystal structure. 

Air pollution is a primary source of exposure to a wide variety of toxic chemicals. The air we breathe contains numerous xenobiotics as well increased concentrations of naturally occurring chemicals such as ozone and particulate matter. The dangers posed by these substances are not limited to inhalation. Skin contact, too, is a primary source of exposure and many lipophilic chemicals are readily absorbed from the vapor phase through the skin. These lipophiles have the propensity to carry hydrophiles with them. 

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