Emerging Pesticides: Trifluralin

A recent ad campaign for Preen, a weed preventer comprised of ~1.5% trifluralin (2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine or α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) caught our attention in a market where glyphosate is a dominant herbicide. Trifluralin is a pre-emergent dinitroaniline herbicide that was first approved for use by the US EPA in the early 1960s and has been assigned CAS Number 1582-09-8.

The EPA Fact Sheet does not offer extensive information about trifluralin, but trifluralin was banned for all uses in Europe in 2009 (read more) because of concerns about its:

• High risk for aquatic organisms (especially fish)
• High persistence in soil
• High potential for bioaccumulation
• Potential for long-range transport via air

While relatively nontoxic In acute exposures to mammals and birds, trifluralin is classified by the US EPA as a possible carcinogen and by the Illinois EPA as a probable endocrine disruptor.

Trifluralin has a very high toxicity to fish and other aquatic organisms, with LC50s in the sub-100 ppb range. Although considered persistent, its affinity for soils, coupled with its relatively low solubility in water, reduces concerns for transport.

CIL has offered deuterated trifluralin since the 1990s.