Objective: To study the effect of low concentration CO on neurobehaviour function and the maximal allowable concentration (MAC) in limited time.
Method: 40 KM (kunming) male mice were randomly divided into groups A, B, C and D. They were exposed to normal air, 30 mg/m3 CO, 300 mg/m3 CO and 600 mg/m3 CO respectively. The changes in neurobehaviour function of the mice before, during and after 72 h exposure in 0.5 m3 static chambers were observed. Four indices were measured: response time (RT) and error rate (ER) in the water maze test, enter check frequency (ECF) and urine or excrement frequency (UEF) in open field test.
Result: The set upright frequency in group D was smaller than those in groups A, B and C during exposure. RT and ER values went in a direction contrary to pre-exposure the four groups in the second 3 days (6 d) after or out of exposure, while ER values showed that group D > group C > group A > group B in the third 3 days (9 d). RT value was not different among the 4 groups, but its order of numerical value was similar to the ER order. The order of ECF values was that group C > group A and group D in 3 d after or out of exposure and not different among the 4 groups in 6 d and group D < group A and group B in 9 d. UEF values were not different among the 4 groups in 3 d and 9 d, but group D > group A and group B in 6 d after or out of exposure. Comparison with every group itself, showed statistically significance increase in ER values in 9 d out of exposure than before exposure in group D. ECF values showed the statistics significant increase in 9 d in group A and B.
Conclusion: Low concentration CO may interfere with the learning and memory of mice in the water maze and impede the development of the motor nervous function and disturb the steadiness of emotion of mice in the open field. In addition, low concentration of CO may be of tardy toxicity.