toxicity class

Assignment to a toxicity class is based typically on results of acute toxicity studies such as the determination of {{LD50}} values in animal experiments, notably rodents, via oral, inhaled, or external application. The experimental design measures the acute death rate of an agent. The toxicity class generally does not address issues of other potential harm of the agent, such as bioaccumulation, issues of carcinogenicity, teratogenicity, mutagenic effects, or the impact on reproduction.

Regulating agencies may require that packaging of the agent be labeled with a signal word, a specific warning label to indicate the level of toxicity.

The World Health Organization (WHO) names four toxicity classes:

• Class I – a: extremely hazardous
• Class I – b: highly hazardous
• Class II: moderately hazardous
• Class III: slightly hazardous

The system is based on LD50 determination in rats, thus an oral solid agent with an LD50 at 5 mg or less/kg bodyweight is Class Ia, at 5–50 mg/kg is Class Ib, LD50 at 50–2000 mg/kg is Class II, and at LD50 at the concentration more than 2000 mg/kg is classified as Class III. Values may differ for liquid oral agents and dermal agents.{{cite web |url=http://www.who.int/ipcs/publications/pesticides_hazard_2009.pdf?ua=1 |title=Archived copy |website=www.who.int |access-date=15 January 2022 |archive-url=https://web.archive.org/web/20140913155457/http://www.who.int/ipcs/publications/pesticides_hazard_2009.pdf?ua=1 |archive-date=13 September 2014 |url-status=dead}}

There are eight toxicity classes in the European Union's classification system, which is regulated by Directive 67/548/EEC:

• Class I: very toxic
• Class II: toxic
• Class III: harmful
• Class IV : corrosive
• Class V : irritant
• Class VI : sensitizing
• Class VII : carcinogenic
• Class VIII : mutagenic

Very toxic and toxic substances are marked by the European toxicity symbol.

{{Main article|Toxicity label}}

The Indian standardized system of toxicity labels for pesticides uses a 4-color system (red, yellow, blue, green) to plainly label containers with the toxicity class of the contents.

{{Main|Toxicity category rating}}

The United States Environmental Protection Agency (EPA) uses four toxicity classes in its toxicity category rating. Classes I to III are required to carry a signal word on the label. Pesticides are regulated in the United States primarily by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

• most toxic;
• requires signal word: "Danger-Poison", with skull and crossbones symbol, possibly followed by:

:"Fatal if swallowed", "Poisonous if inhaled", "Extremely hazardous by skin contact--rapidly absorbed through skin", or "Corrosive--causes eye damage and severe skin burns"

Class I materials are estimated to be fatal to an adult human at a dose of less than 5 grams (less than a teaspoon).

• moderately toxic
• signal word: "Warning", possibly followed by:

:"Harmful or fatal if swallowed", "Harmful or fatal if absorbed through the skin", "Harmful or fatal if inhaled", or "Causes skin and eye irritation"

Class II materials are estimated to be fatal to an adult human at a dose of 5 to 30 grams.

• slightly toxic
• Signal word: Caution, possibly followed by:

:"Harmful if swallowed", "May be harmful if absorbed through the skin", "May be harmful if inhaled", or "May irritate eyes, nose, throat, and skin"

Class III materials are estimated to be fatal to an adult human at some dose in excess of 30 grams.

• practically nontoxic
• no signal word required since 2002

Furthermore, the EPA classifies pesticides into those anybody can apply (general use pesticides), and those that must be applied by or under the supervision of a certified individual. Application of restricted use pesticides requires that a record of the application be kept.

• Dangerous goods
• Hazard symbol
• Globally Harmonized System
• Toxicity label

{{reflist}}

• [https://web.archive.org/web/20040708001948/http://www.who.int/ipcs/publications/pesticides_hazard/en/ WHO Classification document]
• [http://www.ipm.iastate.edu/ipm/hortnews/1994/1-12-1994/undpest.html Reading the label]
• [http://www.agf.gov.bc.ca/pesticides/b_3.htm Canada toxicity symbols]
• [http://grounds-mag.com/mag/grounds_maintenance_protect_yourself/index.html Protect Yourself]
• [https://web.archive.org/web/20051220112755/http://whatcom.wsu.edu/ag/comhort/nooksack/ipmweb/Pesticideselection.html Pesticide ratings]
• [http://npic.orst.edu/factsheets/signalwords.pdf Signal Words Fact Sheet - National Pesticide Information Center]

{{Pesticides}}

{{Toxicology}}

{{Poisoning and toxicity}}

{{Pesticide regulation in the United States}}

Category:Toxicology

Category:Pesticides