Toxicity Criteria

Washington State DOE Toxicity Criteria

Toxic Category: The reagents you use are categorized by the Washington State Department of Ecology (WDOE). The category depends on the LD50 Oral Rat and they are as follows:

Category X: LD50 (oral rat) = <0.5 mg/Kg
Category A: LD50 (oral rat) = 0.5 to 5.0 mg/Kg
Category B: LD50 (oral rat) = 5.0 to 50 mg/Kg
Category C: LD50 (oral rat) = 50 to 500 mg/Kg
Category D: LD50 (oral rat) = 500 to 5,000 mg/Kg

For any chemical wastes (of one or more constituents) you must calculate an "Equivalent Concentration" or EC. Most of your concentrations will be expressed in molar concentrations. So be prepared to convert Molar (M) to Percent (%) wt/vol concentrations.

Chemical Wastes of One Categkory: Find the LD50 oral rat and categorize it into X, A, B, C, or D, and determine the % concentration of your waste. The EC is found by taking the % concentration and weighting it by the following factors:

Category X: None (EC = …X%)
Category A: Divide by 10 (EC = …A%/10)
Category B: Divide by 100 (EC = …B%/100)
Category C: Divide by 1,000 (EC = …C%/1,000)
Category D: Divide by 10,000 (EC = …D%/10,000)

Chemical Wastes of More than One Category: After finding the LD50 oral rat for each component of your waste mixture and categorizing them into X, A, B, C, or D categories, determine the % concentration for each constituent. The EC is found by taking the % concentration and weighting it by the following formula:

EC(%) = …X% + …A%/10 + …B%/100 + …C%/1,000 + …D%/10,000

Chemical Waste Determination: The value of the EC will determine what you will do with your waste. Your waste (which may be a mixture of different categories not exceeding any one category limit) may be disposed of by the sewer system if the EC is less than the following values:

Category X: LD50 (oral rat) = <0.001%
Category A: LD50 (oral rat) = <0.01%
Category B: LD50 (oral rat) = <0.1%
Category C: LD50 (oral rat) = <1.0%
Category D: LD50 (oral rat) = <10%

If the EC is GREATER than the above values: the wastes must be collected and stored as a hazardous waste (to be land-filled or burned later), or treated further to reduce it's toxicity.