ANNEX IV. & CLASSIFICATIONS USEPA’S WHO’S ACUTE TOXICITY Classification is principally determined by the toxicity of the pesticide to rats. The LD50 dose is used to determine toxicity. This is the dose that kills 50% of the rats exposed to the toxicant and it is expressed as milligram (mg) of toxicant per kilogram (kg) of body weight. Usually the oral LD50 is used but if the dermal toxicity puts the pesticide into a more toxic class, then the more restrictive classification is always followed. The classification can also be adjusted by factors other than acute oral or dermal toxicity to represent its true potential to harm. The tables below give the LD50, descriptions and categories for the two classification systems. WHO acute toxicity classifications Category Description Oral LD50 (mg/L) Dermal LD50 (mg/L) Liquid Solid Liquid Solid Ia Extremely hazardous 20 5 10 ‹ ‹ ‹ 40 ‹ Ib Highly hazardous 20-200 5-50 40-400 10-100 II Moderately hazardous 200-2,000 50-500 400-4,000 100-1,000 III Slightly hazardous 4,000 ›2,000 › 500 › ›1000 U Unlikely to present acute hazard in 3,000 2,000 › › normal use USEPA acute toxicity classifications Oral Dermal LD50 Inhalation LD50 Eye Effects Skin Effects Label LC50 (mg/L) (mg/kg) I Danger 50 200 0.05 Corrosive (irreversible Corrosive (tissue ‹ ‹ ‹ destruction of ocular destruction into the tissue) or corneal dermis and/or involvement or irritation scarring) persisting for more than 21 days II 50-500 0.05-0.5 Corneal involvement or Severe irritation at irritation clearing in 72 hours days III Caution 0.5-2 Corneal involvement or Moderate irritation 5,000 irritation clearing in 7 at 72 hours days or less IV None 5,000 2 Minimal effects clearing Mild or slight › › › in less than 24 hours irritation
ANNEX IV. USEPA’S & WHO’S ACUTE TOXICITY CLASSIFICATIONS Classification is principally determined by the toxicity of the pesticide to rats. The LD50 dose is used to determine toxicity. This is the dose that kills 50% of the rats exposed to the toxicant and it is expressed as milligram (mg) of toxicant per kilogram (kg) of body weight. Usually the oral LD50 is used but if the dermal toxicity puts the pesticide into a more toxic class, then the more restrictive classification is always followed. The classification can also be adjusted by factors other than acute oral or dermal toxicity to represent its true potential to harm. The tables below give the LD50, descriptions and categories for the two classification systems. WHO acute toxicity classifications Category Description Oral LD50 (mg/L) Dermal LD50 (mg/L) Liquid Solid Liquid Solid Ia Extremely hazardous ‹ 20 ‹ 5 ‹ 40 ‹ 10 Ib Highly hazardous 20-200 5-50 40-400 10-100 II Moderately hazardous 200-2,000 50-500 400-4,000 100-1,000 III Slightly hazardous ›2,000 › 500 › 4,000 ›1000 U Unlikely to present acute hazard in normal use › 3,000 › 2,000 USEPA acute toxicity classifications Label Oral LD50 Dermal LD50 (mg/kg) Inhalation LC50 (mg/L) Eye Effects Skin Effects I Danger ‹ 50 ‹ 200 ‹ 0.05 Corrosive (irreversible destruction of ocular tissue) or corneal involvement or irritation persisting for more than 21 days Corrosive (tissue destruction into the dermis and/or scarring) II 50-500 0.05-0.5 Corneal involvement or irritation clearing in days Severe irritation at 72 hours III Caution 0.5-2 Corneal involvement or irritation clearing in 7 days or less Moderate irritation at 72 hours IV None › 5,000 › 5,000 › 2 Minimal effects clearing in less than 24 hours Mild or slight irritation
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