Bentazon

Usage

Bentazon controls plants unable to metabolise it. It is considered safe for use on alfalfa, beans (except garbanzo beans), maize, peanuts, peas (with the exception of blackeyed peas), pepper, peppermint, rice, sorghum, soybeans and spearmint; as well as lawns and turf. Bentazon is usually applied aerially or through contact spraying. Bentazon in high heat can give off sulfur and nitrogen fumes.

Bentazon is registered in the US. In 2010 the formulations "Prompt" and "Laddock", both mixtures of bentazon and atrazine, were voluntarily cancelled, though other bentazone products remain available as of 2025.

Environmental behaviour

Bentazon is quickly metabolized by plants and animals. Soil leaching and runoff may cause water contamination. In 1995 the EPA found bentazon in water "exceeding levels of concern". Bentazone is not regulated by the Safe Drinking Water Act. Bentazon was detectable in 64 out of 200 wells in California - the highest number of detections in a 1995 study. In response, California set a bentazon limit in drinking water of 200 ppb (parts per billion).

The EPA forbids application and disposal of bentazon directly into water, just like nearly every single other pesticide also.

Ecotoxicity

Bentazon is non-toxic to honeybees and beetles. It is toxic to rainbow trout and bluegill sunfish at 190 ppm and 616 ppm, respectively. Bentazon affects birds' reproductive capacities.

To mammals, bentazon is moderately toxic if ingested or absorbed through skin. The LD50 is 500 mg/kg for cats, 1100 mg/kg to 2063 mg/kg for rats, 400 mg/kg for mice, and 750 mg/kg for rabbits. Dogs, fed 13.1 mg/day, developed diarrhoea, anemia and dehydration. In another study, dogs developed prostate inflammation also. Bentazon does not cause gene mutations.

Toxicity to humans

Bentazon is non-carcinogenic to humans, based on animal tests. However, there have been no studies on humans. Bentazon can irritate the eyes, skin and respiratory tract; ingesting bentazon causes nausea, diarrhoea, trembling, vomiting and difficulty breathing.

The toxic effects have been seen in humans who killed themselves with bentazon: it caused fevers, renal failure, accelerated heart rate, shortness of breath and hyperthermia. Eating 88 grams of bentazon killed an adult.

Food limits

Food limits are set on bentazon prevent toxic effects. In the US: 0.02 ppm for milk; 0.05 ppm for meat and animal products; 0.05 ppm for dried beans (except soy), corn, bohemian chili peppers, peanuts, rice, soybeans, and sorghum used for fodder and grain; 0.5 ppm for succulent beans and peas; 0.3 ppm for peanut hulls; 1 ppm for mint and dried peas; 3 ppm for rice (straw), and corn and peanuts used in hay or forage; 8 ppm for pea vine hays (dried), and soybeans used for foraging or hay.

References

References

1. Fan, Anna M.. (February 1999). "Public Health Goal for Bentazon in Drinking Water". Office of Environmental Health Hazard Assessment.
2. "Pesticide Information Profile: Bentazon". Cornell University.
3. "Classification of Herbicides According to Site of Action".
4. "Reregistration Eligibility Decision (RED) Facts". United States Environmental Protection Agency.
5. OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES. "Reregistration Eligibility Decision: Bentazon". United States Environmental Protection Agency.
6. "Laddok Herbicide pesticide information".
7. "Laddok 5L Herbicide pesticide information".
8. "Prompt 5L Herbicide pesticide information".
9. "Prompt Herbicide pesticide information".
10. Huber, R.. (September 1994). "Reviews of Environmental Contamination and Toxicology".
11. (February 1998). "TOXICOLOGICAL REVIEW of BENTAZON: In Support of Summary Information on the Integrated Risk Information System (IRIS)". United States Environmental Protection Agency.
12. (1990). "National Pesticide Survey". United States Environmental Protection Agency.
13. "Bentazon (Basagran) (CASRN 25057-89-0)". United States Environmental Protection Agency.
14. "Bentazon: Emergency Medical Treatment". Hazardous Substances Data Bank.