Content area
Full Text
Triallate (S-2, 3, 3, trichloroallyl diisopropyl thiocarbamate) is the active ingredient in several preemergent herbicides. Toxicological research has shown neurological abnormalities among rats fed very high repeated doses of triallate. 1- 3 These included axonal and myelin degeneration in the gracilus tract of the spinal cord at 500 ppm; axonal and myelin degeneration in the gracilus tract and in the sural, sciatic, and tibial nerves, and functional behavioural changes at 2000 ppm; and behavioural changes associated with axonal degeneration in the brain stem (medial longitudinal fasicilus and the facial motor nerve) at 6000 ppm. Decreased body weight gain or a loss in body weight occurred at all dose levels.
The specific regions of the peripheral and central nervous systems affected in rats in high dose studies are present in humans and have similar functions. In humans, axonal degeneration of peripheral nerves in the lower limbs would cause muscle weakness and sensory deficits of lower extremities. Axonal degeneration in the spinal cord, brain stem, and cerebellum would result in disturbances of coordination (eye, extremities), proprioception (awareness of body position in space), vibration sensation, gait, and balance. Degenerated axons in the trigeminal and facial cranial nerves would produce impaired sensation over the face and weakness of facial muscles, respectively.
Neurological health has not been assessed in people who work with triallate. The present study of triallate formulation workers evaluated the relation between neurological function and an indicator of cumulative exposure to triallate, as well as certain personal attributes, lifestyle factors, medical conditions, and occupational exposure to agents other than triallate.
METHODS
Plant operations
The study plant opened in 1961 as an anhydrous ammonia storage terminal. Its primary operations have been the manufacture, formulation, and packaging of herbicide ingredients or herbicides and the production of plastics. Current operations include the formulation of triallate, the production and formulation of acetanilide herbicides, and the production of glyphosate.
Triallate is formulated and packaged in annual campaigns that last approximately three months. Liquid formulation of triallate began around 1970, and granular formulation began in 1972. In liquid formulation, triallate is mixed with aromatic solvents (mainly trimethyl benzenes, xylenes, or cumene), emulsifiers, and antifoaming agents in outdoor closed blend tanks. The finished product is packaged in plastic jugs or drummed. In granular formulation,...