Iron, zinc and copper levels in brain, serum and liver of neonates exposed to 2,4-dichlorophenoxyacetic acid.

The effects of 2,4-dichlorophenoxyacetic acid (2,4-D, 70 or 100 mg/kg dam's body weight) on iron (Fe), zinc (Zn) and copper (Cu) in brain, liver and serum of well-nourished and undernourished pups exposed through dam's milk were determined. Undernourishment produced a high Fe decrease (serum and brain) and a delay in weight gain similar to that produced by the highest dose of 2,4-D on well-fed pups. In the latter animals, copper was found to be the most altered ion, increasing its level in serum, liver and some brain areas and decreasing in whole brain. Zinc was the most affected ion in brain areas. Well-nourished pups lactationally exposed to 70 mg 2,4-D/kg dam's body weight altered neither their metal levels nor their body weight in any of the tissues studied. Undernourished pups were more vulnerable to the 2,4-D effect than well-nourished pups. Undernourished pups exposed to a lower 2,4-D dose showed a decrease in their body, brain and liver weight similar to well-fed animals exposed to 100 mg 2,4-D/kg. A noticeable decrease in liver L-tryptophan peroxidase activity by 2,4-D was also registered. This effect was higher in undernourished and 2,4-D-exposed pups. These results suggest that brain areas have a different susceptibility to the herbicide and that undernourishment produces a higher vulnerability to the herbicide and exacerbates the 2,4-D effect.