Toxicity of mixtures of parathion, toxaphene and/or 2,4-D in mice

The toxicity of the mixtures of parathion (PA), toxaphene (TOX) and/or 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in ICR male mice (21–24 g) by oral intubation, in corn oil, daily for up to 14 days. On Day 15, the exposure was discontinued, and animals were monitored for an additional period of 7 days for the possible reversibility of the toxicity. The body weight gain decreased with the mixtures, as well as with the individual agricultural chemicals (ACs), during the 14-day period. The cholinesterase (ChE) activity in the serum and brain was inhibited in the animals of the groups of PA (1–10 mg kg−1) and PA (5 mg kg−1)-containing mixtures. TOX (50–200 mg kg−1) caused initial inhibitory effects of 20–65% on the serum ChE (Day 1) before producing increases of 53–64% in the enzyme activity by Day 15, with little effects on the brain ChE levels. 2,4-D (50–200 mg kg−1) resulted in significantly elevated levels of the serum ChE, with substantial decreases in the brain ChE activity. The serum glutamic pyruvic transaminase level was up (38–630%) in TOX (50 mg kg−1), 2,4-D (50 mg kg−1) or their mixture group. No pathological changes at the light microscopic level in the brain and liver were noticed. TOX and TOX-containing mixtures significantly increased the liver/body weight ratio and decreased the pentobarbital (60 mg kg−1, i.p., in saline)-induced sleep. When TOX (50 mg kg−1) and PA (5 mg kg−1) + TOX (50 mg kg−1) groups were examined, the dilatation of the hepatic endoplasmic reticulum was distinguished and the decrease in the level of pentobarbital in the serum, brain, liver and kidneys was noted. The effects produced by these chemicals singly, as well as by their mixtures, appeared to be reversible in nature. The toxic effects exhibited by the mixtures of PA (5 mg kg−1), TOX (50 mg kg−1) and/or 2,4-D (50 mg kg−1) were found to be the resultant of the effects showed by their components individually.