Esters of Carbonic and Orthocarbonic Acid, Organic Phosphorous, Monocarboxylic Halogenated Acids, Haloalcohols, and Organic Silicon

This chapter covers (1) esters of carbonic and orthocarbonic acid, (2) esters of organic phosphorous compounds, (3) esters of monocarboxylic halogenated acids, alkanols, or haloalcohols, and (4) organic silicon esters. Other classes of esters are summarized in Chapters 57 and 58. Refer to the Introduction in Chapter 57 for a more detailed overview of general properties of esters. Unfortunately, as shown in the two prior chapters, mainly fragmented toxicological evaluations are available for esters. Most of these esters are characterized by low toxicity. Indeed, as expressed in Chapter 57, lethal dose (e.g., LD50) values are frequently difficult or impractical to measure. Localized dermal irritation is one common effect characteristic of exposures to most organic solvents. Few esters are readily absorbed, but there are exceptions, such as tri-o-cresyl phosphate (TOCP). Several of the halogenated derivatives, such as ethylchloro- and ethylbromo-, are potent lacrimators. Ethyl fluoroacetate and fluoroacetic acid exhibit about the same mode of action, which may indicate that the acetate is rapidly hydrolyzed and metabolized in the mammalian system. The unsaturated carbonates are also associated with high lacrimatory activity. TOCP is an example of an ester that can cause neuropathy in a variety of animal species. The initial weakness and paralysis are normally reversible in early stages, but repeated or massive assaults result in demyelination of the nerve fibers. The mechanism of action is not yet certain, but it appears to involve phosphorylation of proteins. Only selected phosphates exhibit neuropathic effects, including diisopropyl fluorophosphorate and N,N′-diisopropyl phosphorodiamidic fluoride. As was expressed in Chapter 57, industrial hygiene evaluation of esters involves collecting and analyzing air samples to determine their airborne concentrations. Published industrial hygiene air sampling and analytical methods, however, are unavailable for most esters. In relation, there are few occupational exposure and biological limits. A list of ester compounds covered in this chapter that have industrial hygiene sampling and analytical methods are presented here along with their respective occupational exposure limits, established by the American Conference of Governmental Industrial Hygienists (ACGIH), the Occupational Safety and Health Administration (OSHA), and the National Institute for Occupational Safety and Health (NIOSH). As stated in Chapter 57, since sampling and analytical methods and occupational exposure limits are subject to periodic revision, the reader is encouraged to refer to current publications of ACGIH, OSHA, and NIOSH. Keywords: alkyl phosphates; alkyl phosphines; aryl phosphates; aryl phosphines; bromoesters; carbonates; chloroesters; cyclic carbonates; esters of organic phosphorus compounds; fluroesters; haloalcohols; halogenated phosphate esters; organic silicon esters; ortho acid esters; silanal esters; silanes