ABSTRACT
The data was collected about the blood group type distribution among the blood donors in Alareesh Blood Bank during the three years 1992-1994. The calculations indicated that the majority of the donors were carriers of blood group [A] [38%] and blood group [O] [37%], followed by blood group [B] [19%], while blood group [AB] was only 6%. Fourteen blood samples: 4 of [A], 4 of [B], 4 of [O], and 2 of [AB] were taken from 1994 donors. The specific activities of the four enzymes: AChE, GOT, GPT and LDH were determined in each of the 14 samples. Average specific activities of the four enzymes tend to be higher in blood group [A], then [0] with only slight decrease, followed by [B], while the least activities were for blood group [AB]. Molar I[50] values of AChE in different blood groups by the OP insecticide dimethoate, showed that blood group [O] was the most responsive with the least M I[50] value, followed by blood group [A], then [B], and [AB] was the least affected. The results proved the significant impact of the genetic specificity of the blood group type which results in great variation in the susceptibility of individuals towards toxicants and stresses. This broad variation implies the use of wide range of safety factors in risk assessment of exposure to residues of pesticides and in setting the acceptable daily intakes [ADIs]