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Pesticide databaseExplainerChecked 2026-10-01

Most and least toxic pesticides, ranked (acute toxicity, ADI, carcinogenicity)

WHO acute toxicity, Japan’s ADI and IARC classification, ranked by each yardstick

In short

There are three yardsticks for “toxicity.” ① Acute toxicity from a large single dose (WHO class; Japan’s poisonous and deleterious substances), ② the ADI for eating over a long time, and ③ the strength of evidence for carcinogenicity (IARC). The same ingredient can rank differently on each.

Many of the ingredients in the most acutely toxic WHO class (Ia) have had their registration in Japan expired. Of the formulated products registered now, 90.5% are “ordinary substances” (neither poisonous nor deleterious substances).

Every ranking here ranks the properties of the active ingredient itself (hazard). The amounts left in food are very small, so these are not rankings of actual health risk. Even the ingredient eaten most in ordinary meals was under 0.5% of its ADI (Consumer Affairs Agency, fiscal 2024) → How maximum residue limits are set

① Acute toxicity: a large single dose

WHO sorts pesticides into five classes by LD50: the amount (mg per kg of body weight) that kills half of the animals, mainly rats, given the undiluted active ingredient once by mouth. The smaller the LD50, the stronger the acute toxicity.

Active ingredients with high acute toxicity (WHO LD50, oral, rat; the smaller, the more toxic) The 20 active ingredients with the smallest WHO 2019 LD50 values, in ascending order: Aldicarb 0.93 mg/kg (Ia), Carbofuran 8 mg/kg (Ib), Abamectin 8.7 mg/kg (Ib), Parathion 13 mg/kg (Ia), Methomyl 17 mg/kg (Ib), Tefluthrin c22 mg/kg (Ib), Methamidophos 30 mg/kg (Ib), Bifenthrin c55 mg/kg (II), Methyl isothiocyanate 72 mg/kg (II), Endosulfan 80 mg/kg (II), Fipronil 92 mg/kg (II), Isoxathion 112 mg/kg (Ib), DDT 113 mg/kg (II), Chlorpyrifos 135 mg/kg (II), Acetamiprid c140 mg/kg (II), Dimethoate c150 mg/kg (II), Paraquat 150 mg/kg (II), Benfuracarb 205 mg/kg (II), Permethrin c220 mg/kg (II), Imazalil 227 mg/kg (II). The scale is logarithmic. Includes ingredients whose registration in Japan has expired. Ia, Ib II III 1 10 100 1,000 10,000 Aldicarb (expired / not registered) 0.93 (Ia) Carbofuran (expired / not registered) 8 (Ib) Abamectin 8.7 (Ib) Parathion (expired / not registered) 13 (Ia) Methomyl 17 (Ib) Tefluthrin c22 (Ib) Methamidophos (expired / not registered) 30 (Ib) Bifenthrin c55 (II) Methyl isothiocyanate 72 (II) Endosulfan (expired / not registered) 80 (II) Fipronil 92 (II) Isoxathion 112 (Ib) DDT (expired / not registered) 113 (II) Chlorpyrifos (expired / not registered) 135 (II) Acetamiprid c140 (II) Dimethoate c150 (II) Paraquat 150 (II) Benfuracarb 205 (II) Permethrin c220 (II) Imazalil (expired / not registered) 227 (II) LD50 (mg/kg body weight). Source: WHO Recommended Classification of Pesticides by Hazard 2019
Figure: The 20 active ingredients in this database with the smallest WHO LD50 (oral)

WHO Ia (Extremely hazardous)　3 ingredients

WHO Ib (Highly hazardous)　8 ingredients

WHO II (Moderately hazardous)　69 ingredients

WHO III (Slightly hazardous)　36 ingredients

WHO U (Unlikely to present acute hazard in normal use)　38 ingredients

Numbers are LD50 (mg/kg). “c” marks a value chosen for classification from a widely varying range. Fumigants (used as gas) are outside WHO’s classes. Some newer ingredients are not in WHO 2019.

Japan’s “poisonous” and “deleterious” substances

Under the Poisonous and Deleterious Substances Control Act, Japan designates substances with strong acute toxicity as “poisonous substances” (the strongest as “specified poisons”) and the next strongest as “deleterious substances.” Those that fall into neither are called “ordinary substances.”

Toxicity classes of the 3,741 registered pesticide formulated products (as of September 30, 2026) Ordinary substance 3,385 (90.5%), deleterious substance 228 (6.1%), poisonous substance 4 (0.1%), specified poison 11 (0.3%; all aluminum phosphide fumigants), not classified 113 (3.0%; natural-enemy and microbial pesticides). Ordinary substance 3385 Deleterious substance 228 Poisonous substance 4 Specified poison 11 Not classified (natural enemies, microbes) 113 Ordinary substance 3,385 (90.5%) Deleterious substance 228 (6.1%) Poisonous substance 4 (0.1%) Specified poison 11 (0.3%) Not classified (natural enemies and microbes) 113 (3.0%)
Figure: Classes of the 3,741 formulated pesticide products registered now (FAMIC, as of September 30, 2026)
  • All 11 specified-poison products are aluminum phosphide fumigants. The 4 poisonous-substance products are a hydrogen cyanide fumigant, two diquat/paraquat liquid products, and a sulfuryl fluoride fumigant.
  • It used to be different. By share of production value, 1970 was 0.4% specified poisons and 6.8% poisonous substances; 2010 was 0.0% specified poisons, 0.8% poisonous substances, 14.9% deleterious substances and 84.3% ordinary substances (Plant Protection Vol. 68, No. 10; tabulated from the Nouyaku Yoran yearbook).

Active ingredient itself is a specified poison (registered ingredients in this database)

Active ingredient itself is a poisonous substance (registered ingredients in this database)

Active ingredient itself is a deleterious substance (registered ingredients in this database)

Even when an ingredient is a deleterious substance, many diluted formulated products are ordinary substances (for example, “Deleterious (ordinary at 2% or less)” means products with 2% or less of the ingredient are ordinary substances). See “Classes of formulated products” on each ingredient’s page for details.

② ADI: eating over a long time

The ADI (acceptable daily intake) is the amount considered to have no effect on health even if eaten every day for a lifetime. The smaller the ADI, the smaller the amount allowed (the stronger the chronic toxicity). In Japan it is set by the Food Safety Commission of Japan (FSCJ).

Active ingredients with the smallest ADI (acceptable daily intake), Food Safety Commission of Japan The 20 active ingredients with the smallest ADI, in ascending order: Carbofuran 0.00015, Fipronil 0.00019, Ethoprophos 0.00025, Aldicarb 0.00025, Profenofos 0.0005, Emamectin Benzoate 0.0005, Methamidophos 0.00056, Abamectin 0.0006, Diazinon 0.001, Chlorpyrifos 0.001, Chloropicrin 0.001, MCPA 0.0019, Fosthiazate 0.002, Isoxathion 0.002, Iminoctadine 0.0023, Acephate 0.0024, Prothiofos 0.0027, Oxadiazon 0.0036, Tetraconazole 0.004, Methyl isothiocyanate 0.004 (mg/kg body weight/day). The scale is logarithmic. The smaller the ADI, the smaller the amount allowed when eaten over a long period. 0.0001 0.001 0.01 0.1 1 Carbofuran (expired / not registered) 0.00015 Fipronil 0.00019 Ethoprophos (expired / not registered) 0.00025 Aldicarb (expired / not registered) 0.00025 Profenofos (expired / not registered) 0.0005 Emamectin Benzoate 0.0005 Methamidophos (expired / not registered) 0.00056 Abamectin 0.0006 Diazinon 0.001 Chlorpyrifos (expired / not registered) 0.001 Chloropicrin 0.001 MCPA 0.0019 Fosthiazate 0.002 Isoxathion 0.002 Iminoctadine 0.0023 Acephate 0.0024 Prothiofos 0.0027 Oxadiazon 0.0036 Tetraconazole 0.004 Methyl isothiocyanate 0.004 ADI (mg/kg body weight/day). Source: Food Safety Commission of Japan, pesticide evaluation reports (checked October 1, 2026)
Figure: The 20 active ingredients with the smallest ADI (mg/kg body weight/day, FSCJ)

Ingredients with a large ADI (larger amounts allowed)

Active ingredientADI (mg/kg body weight/day)
Chlorantraniliprole1.5
Glyphosate1
Fosetyl0.88
Nitenpyram0.53
Asulam0.36
Validamycin0.36
Kresoxim-methyl0.36
Fludioxonil0.33
Dicamba0.3
Malathion0.29
Maleic hydrazide0.25
Dinotefuran0.22

Acute toxicity and ADI are separate yardsticks. For example, glyphosate is WHO III (slightly hazardous) and has a large ADI of 1, yet IARC classifies it in Group 2A.

③ Carcinogenicity: IARC classification

IARC (the International Agency for Research on Cancer) classifies a substance by the strength of the evidence that it can cause cancer. It does not show how large the risk is at a given intake (Group 1 also includes tobacco and processed meat).

Group 1 (carcinogenic to humans)

Group 2A (probably carcinogenic to humans)

Group 2B (possibly carcinogenic to humans)

The weaker end: low acute toxicity and a large ADI

Examples of ingredients classed by WHO as “U” (unlikely to present acute hazard in normal use) and registered in Japan:

Sulfur, sodium bicarbonate (baking soda), machine oil and others are “substances exempt” from the positive list system (substances clearly shown not to harm human health), so no maximum residue limit is set for them.

Sources

Last checked 2026-10-01. Systems and figures change over time. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.

This page lists facts from laws, public agencies' documents and peer-reviewed papers. It does not judge whether any particular pesticide or farming method is good or bad.

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