Hazard Characteristics of Common Toxic Chemicals

Chemical C Upper Lower class TWA skin Special hazards  

Appendix 2 Hazard Characteristics of Common Toxic Chemicals 

Chemical Flash point, C Explosive limits, % D.O.T. class TLV- TWA Absorbed through skin s Special hazards  

Chlorobenzene Chlorodiphenyl (PCBs) 2-Chloroethanol (ethylene chlorohydrin) 

Chromic acid Chromium, chromium compounds Chromium potassium sulfate 

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The characteristics of a chemical or substance that would categorize it as a reactive material include (1) it reacts violently with water, (2) it forms potentially explosive mixtures with water, or (3) when mixed widi water or other chemicals, it generates toxic gases, vapors or fumes in a quantity sufficient to present a danger to human health or the environment. Because water is the most common fire suppressant, the characteristic of reactivity is especially relevant since the application of water to eliminate or prevent the spread fires may be counterpro-ductive rather than helpful. Several categories of chemicals will be discussed from this standpoint however, several of these same chemicals also present additional hazards. 

Table 2 lists some of the physical, toxicity, flammability, and reactivity properties of common chemicals (10,13,42,45—51). Also given are some of the quantities specified for reporting spills and for compliance with legislated requirements. The OSHA regulations require that material safety data sheets (MSDS) be developed for all process materials, so that the hazard data can be communicated to employees (52). Characteristics of toxicity, flammability, chemical instability, reactivity and reaction energy, operating conditions, and corrosive properties of construction materials must all be considered in analyzing hazard potentials of chemicals and chemical operations. 

The Dow Fire and Explosion Index (FEI) (12) and the Dow Chemical Exposure Index (CEI) (14) are two commonly used tools that measure inherent safety characteristics. Gowland (25) reports on the use of the FEI and CEI in the development of safety improvements for a urethane plant. Tables 1 and 2 illustrate the application of the FEI and CEI in measuring inherent safety characteristics of process design options. These indices measure the inherent safety characteristics of processes in only two specific areas—fire and explosion hazards and acute chemical inhalation toxicity hazards. Other indices would be required to evaluate other types of hazards. 

Waste that is regulated as hazardous because of its chemical properties is defined by EPA in two ways (1) waste that has certain hazardous characteristics and (2) waste that is on certain lists of chemicals. The first category is based on properties of materials that should be familiar to every laboratory worker. The second category is based on lists, established by EPA and certain states, of certain chemicals common to industry. These lists generally include materials that are widely used and recognized as hazardous. Chemicals are placed on these RCRA lists primarily on the basis of their toxicity. (To determine if waste is hazardous or not, see Chapter 9, section 9.D.2.)... 

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