EHA Library - The official digital education library of European Hematology Association (EHA)

Pesticides are extensively used in agriculture today. Fungicides based on derivatives of triazole are the most widespread all over the world. Tebuconazole (TB) is one of the most frequently used substance of this group. Literature review confirms that triazole fungicides have the ability to cause different hematotoxic effects.

Since 2007-2016 years we have investigated 10 test-substances of generic tebuconazoles (purity up to 97 %) from different manufacturers with purpose to assess their hematotoxic action on males Wistar Han rats peripheral blood in the subchronic 90-days oral toxicity study (according to SOP and OECD 408 reccomendations in compliance with GLP).

The Wistar Han males were randomly allotted to four groups. The input controls of peripheral blood parameters were conducted after a period of animals acclimatization. The goal was to evaluate the physiological state of the Wistar Han rats and the blood picture before treatment. Doses 0; 10; 50; 200 mg/kg/bw/day were defined and were the same in all studies. Blood samples for hematological measurements were examined at 4, 9, 13 weeks after TB exposure in the same groups of animals throughout the experiment. Hemoglobin (HGB) concentration, hematocrit (HCT), total amount of erytrocytes (RBC), leukocytes (WBC) and platelets (PLT), mean corpuscular hemoglobin (MCH) were evaluated.

As a result, all generic TBs on high toxic doses level (200 mg/kg/bw/day) had shown the tendencies for quantitative hematological changes. TBs mainly provoked the significant decrease of HGB concentration and RBC count on 4th and 9th weeks of exposure. Morphological changes of RBC (anisocytosis) were seen too. It means that generic TBs had anemic effect. In general, changes of hematological parameters were not principally significant and did not differ from control values at 13th weeks of experiments, except two TB’s, which had shown significant decrease of HGB. Also some of generic TBs lead to decrease (leukopenia) or increase (leukocytosis) of leukocytes count in peripheral blood. In case of generic pesticides, the presence of impurities can demonstrate various hematotoxic action. Also the adverse effects on peripheral blood of males Wistar Han rats were observed at a dose of 50 mg/kg/bw/day and demonstrated the lesions of red blood. But abovementioned changes were not so clearly expressed. Any adverse hematotoxic effects at 10 mg/kg/bw/day dose were not observed in all studies.

As a conclusion, due to our results the triazole fungicides generic tebuconazoles have hematotoxic action. They induce anemia in Wistar Han rats and quantitative white blood cells changes. Today it is very important to investigate the hazardous effects of pesticides on the blood system.