Toxicity Categories

Undoubtedly, fire hazard is partially associated with the toxicity of the smoke itself. The smoke of a variety of common materials, as measured e.g. by the NBS cup furnace toxicity test [10], has recently been compared with the intrinsic toxic potency of other poisons and of toxic gases, as well as with toxicity categories [11]. It has been shown that toxicity is a relatively minor factor because there is very little difference between the intrinsic toxic potency of the smoke of the majority of common materials, with very few exceptions. 

In California, mixer-loaders and spray applicators who work with toxicity category I and II organophosphates or N-methyl carbamates more than 30 hours per 30-day period are required to have medical supervision. Supervision consists of an interview and a medical examination to determine if a medical condition exists which would make the worker unusually susceptible to poisoning due to cholinesterase inhibition, and to caution the individual about the use of certain drugs such as the pheno-thiazine tranquilizers vdtich potentiate the effects of cholinesterase (ChE) inhibition. Two blood samples, taken several days apart, are analyzed to determine the individual s preexposure plasma and red blood cell (RBC) ChE activity (baseline value). The physician arranges a routine ChE testing program and provides for extra ChE tests should the worker be accidently exposed to OP s. If ChE activity is depressed to 50 percent of the baseline value, the physician may ask the employer to place the worker on... 

Studies on the Effectiveness of Closed-Transfer Systems for Mixing and Loading Toxicity Category I and II Products Containing Organophosphates and N-methyl Carbamates... 

The use of closed systems has been required in California for transfer of toxicity category one liquid pesticides from the manufacturer s container into the mix tank and then into the application vehicle tank. It appears that this process has considerably reduced both dermal and inhalation exposure. The use of probes that are inserted and then removed from containers reduces dermal exposure up to ten-fold it also appears that the use of built-in probes further reduces exposure to the mixer-loader by up to another ten-fold factor in some cases. 

Test sample Concentration ratio of Cl-MTT(wt%) Primary irritation index (PE) Dermal irritation toxicity categories... 

Acute oral toxicity of MB in rats is 214 mg/kg, and the compound belongs to toxicity category II. In view of its acute inhalation toxicity in humans and its history of use, it is grouped under category I. Accordingly, the LD50 in rats is 2,700 ppm for a 30-minute exposure, whereas in humans, a dose of 1,583 ppm (6.2 mg/L) for approximately 15 to 20 hours was found to be lethal. A much... 

APPENDIX 6 USEPA LABELING TOXICITY CATEGORIES BY HAZARD INDICATOR 525... 

The hiunan health assessment for strychnine is based on the acute toxicity. Strychnine has been placed in Toxicity Category I, indicating the greatest degree of acute toxicity, for oral and ocular effects. It has been reported that the probable lethal oral dose is 1.5 to 2mg/kg (Gosselin et al, 1984). Inhalation toxicity is also presumed to be high. An oral dose of 1.5 to 2 mg/kg is equivalent to 70 to 93 mg/m exposure for 30 min for a 70 kg human being. 

Signal words can be found on the product label. See Chapter 5, Table 5.1, for toxicity categories and their respective signal words. 

Table 5.2 shows how signal words can be used to select the appropriate personal protective equipment (PPE) for different toxicity categories. In aU cases follow label instructions. 

Usually, the label will not give specific information on the pesticide s toxicity to humans. It must, however, indicate the pesticide s relative toxicity. It does so by using signal words that are established by law that identify the toxicity category to which the product is assigned. Signal words must appear in large letters on the label s front panel. 

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