The aim of the study was the evaluation of the toxic effect of a twocomponent,
preparation Nurelle D 550 EC (500 g of chlorpyrifos and 50 g cypermethrin
per 1 l), administrated dermally. Toxicity was evaluated from histological and
ultrastructural studies of the internal organs and immunotoxic effects (evaluation of
phagocytical and bactericidal activity of neutrophils). The preparation for dermal
application was applied in 2 concentrations (200 mg/kg/day of chlorpyrifos plus 20
mg/kg/day of cypermethrin or 1000 mg/kg/day of chlorpyrifos, plus 100 mg/kg/day of
cypermethrin). The preparation was administrated on the tail skin of female Wistar rats
for 4 hours daily for a period of 4 weeks. After 28 days of the experiment, the animals
were anaesthetised and blood was taken from the heart to evaluate the granulocyte
system. The following organs were taken for histological studies: liver, kidney, lung,
heart, spleen, thymus and lymph nodes. Ultrastructural studies were carried out on the
lung, liver, kidney and heart. The results of the study showed that dermal application of
the pesticide Nurelle D 550 EC resulted in slight morphological and ultrastructural
changes in the liver, kidney, lung and heart. The preparation examined slightly elevated
the bactericidal activity of neutrophils. The differences, however, were not statistically
significant. The phagocytic reaction in animals of both experimental groups did not
differ from that observed in control group