Persistence increases in soils with elevated clay or organic matter content, suggesting the compound has somewhat limited bioavailability to microorganisms in these environments.

Under aerobic conditions in soils or pure cultures, products of bromoxynil degradation often retain the original bromine groups.

The herbicide, and one of its common degradation products (3,5-dibromo-4-hydroxybenzoic acid) have been shown to undergo metabolic reductive dehalogenation by the microorganism Desulfitobacterium chlororespirans.

[6] In the Great Plains region of Canada, where it is widely used on cereal grains, average levels detected in drinking water were 1 nanogram per liter.

Chronic exposure for more than one year in humans caused symptoms of weight loss, fever, vomiting, headache, and urinary problems in one documented case.