Toxicity rating system

Compound Use Class Toxicity rating System GA RI System GK RRT Molecular weight Base mjz... 

The problem of toxic pollutants is difficult to handle because of the great variety of chemicals involved. They represent a hazard not only to aquatic life, but also to human health, either through direct exposure or indirectly through consumption of contaminated fish or waterfowl. The degree of hazard depends on the pollutanf s toxicity, rate of discharge, persistence and distribution in the aquatic system, and bioaccumulation potential. Some highly volatile compounds, when discharged into water, evaporate and become air pollutants. 

Like n-hexane, cyclohexane has a toxicity rating of 3, moderately toxic (see Table 6.1 for toxicity ratings). Cyclohexane acts as a weak anesthetic similar to, but more potent than, n-hexane. Systemic effects have not been shown in humans. 

Phosgene has been included in various hazard rating systems in which the actuai hazard, rather than just toxicity, is evaluated [1206,1623,1957]. A vapour hazard index (a measure of the amount by which a saturated atmosphere of a materiai exceeds the TLV) for phosgene is estimated to be 10000. The index takes account of the volatility of the material, in addition to its toxicity for comparison the value for dichlorine is 1000 [1623]. 

The Chimiotox (Scroggins, 1999) is another rating system developed for the St. Lawrence River Action Plan as a companion to the PEEP index. It is not a toxicity index, because toxicity is not measured. Chemical profiles of municipal and industrial effluents and known toxicity data are used to rank the effluents for potential environmental damage. The daily load of each chemical component is multiplied by a toxicity factor, and the sum of toxic loads produces the rating. 

The toxicity of a chemical also varies from one animal to the next. The LD50 for the common insecticide Diazinon is 300 to 400 mg/kg in rats, while in birds it is 2.75 mg/kg. Theobromine, a chemical found in chocolate, is toxic to dogs but not to rodents. Although largely extrapolated from animal tests, a rating system for acute chemical toxicity for humans has been devised and is presented in Table 1. 

Analyzing toxicity from the point of view of NFPA hazard rating system, the nucleating agents have health rating of 0-1 (exception catbon nanotubes 1-2), This means either no unusual hazard or may be irritating . Also flammability and reactivity ratings are low (in most cases 0-1). 

For mixtures, other than those listed in V-1 (medical), CGA V-7, Standard Method of Determining Cylinder Valve Outlet Connections for Industrial Gas Mixtures should be consulted. This publication, through the use of a rating system, takes into account flammability and toxicity in the selection of the recommended outlet connection. Two additional publications, CGA P-20, Standard for the Classification of Toxic Gas Mixtures and CGA P-23, Standard for Categorizing Gas Mixtures Containing Flammable and Nonflammable Components should also be consulted. 

GI Tract Toxicity rating is low (2 to 3) because strontium salts are poorly absorbed from the digestive system. Large doses may, however, upset the osmotic balance and cause vomiting and diarrhea as... 

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