A hundred and ten days direct contact of pigs with wooden grates impregnated with Pentor 70 did not result in the arising of any obvious changes or reactions in the skin or in the lowering of efficiency. A per os intake of feed mixture with a content of 3 p. c. of sawdust impregnated with Pentor 70 resulted in the lowering of efficiency and in the arising of pathological changes in the digestive tract and in the livers. In experiments performed with rats, the contact with the impregnated sawdust and also the combination of the contact and per os acceptance resulted in changes in the respiratory organs of rats and in young rats in mortality. A limiting factor regarding the use of Pentor 70 in premises intended for pigs is the danger of gnawing impregnated wooden objects.