Fenthion

MedEd Pesticide lists Fenthion as an insecticide in the organophosphate class.

MedEd Pesticide Summarizes Fenthion at a Glance

Type

Insecticide

Chemical class

Organophosphate

CAS number

55-38-9

Formula

C10H15O3PS2

Molar mass

278.3 g/mol

EU status

Not approved as an active substance in the EU.

US status

Not registered with EPA. All 112 products that contained Fenthion are cancelled.

MedEd Pesticide Summarizes Fenthion’s Toxicity Records

MedEd Pesticide holds 92 toxicity records for Fenthion, from 5 sources. The headline values are below.

Oral LD50 in ratsAcute, swallowed

Lowest reported 180 mg/kg, median 180 mg/kg, from 1 record.

Dermal LD50Acute, skin contact

Lowest reported 330 mg/kg, median 458 mg/kg, from 2 records.

Lowest NOAELLong term, mammals

0.03 mg/kg-day in mouse, 102 weeks. Source: ToxRefDB.

See all 92 Fenthion toxicity records in the explorer. The records come from EPA’s Toxicity Values Database, and the methodology explains their limits.

MedEd Pesticide Reports Fenthion’s EU Safety Reference Values

MedEd Pesticide takes these values from the EU, which sets them when it assesses an active substance. They are expressed per kilogram of body weight.

ARfDAcute reference dose

0.01 mg/kg bw/dayThe amount that can be taken in over a short period, such as one meal or one day, without appreciable health risk.

MedEd Pesticide Lists Fenthion’s EU Hazard Classification

MedEd Pesticide lists the harmonised EU hazard statements for Fenthion below.

• H331 Toxic if inhaled
• H302 Harmful if swallowed
• H312 Harmful in contact with skin
• H400 Very toxic to aquatic life
• H410 Very toxic to aquatic life with long-lasting effects
• H341 Suspected of causing genetic defects
• H372 Causes damage to organs through prolonged or repeated exposure

MedEd Pesticide takes EU status, reference values and hazard classification from the EU Pesticides Database. MedEd Pesticide takes US status from EPA’s Pesticide Product Information System (dated 2026-10-13) and chemical identity from PubChem. Retrieved 2026-10-16. Values and approvals change, so check the source for the current entry. See the methodology and the glossary, or compare Fenthion with another pesticide.

MedEd Pesticide. (2026). Fenthion. https://mededpesticide.org/pesticides/fenthion/ (accessed Month Day, Year)