选某石油站70名加油工人为接触组,其中男41名,女29名;年龄20～53岁,平均33岁;工龄1～31年,平均8.7年。另选不接触毒物的53名工人为对照组,其中男28名,女25名;年龄20～45岁,平均30岁;工龄1～28年,平均8.3年。两组工人的年龄、工龄比较,均无显著性差异(P>0.05)。 Selected a petrol station 70 refueling workers for the contact group, 41 males and 29 females; aged 20 to 53 years old, with an average of 33 years; length of service 1 to 31 years, an average of 8.7 years. The other 53 workers without exposure to poison were the control group, 28 were males and 25 were females; the average age was 20 to 45 years old and the average age was 30 years; the length of service was 1 to 28 years, an average of 8.3 years. There was no significant difference between two groups of workers in age and length of service (P> 0.05).