Neuropsychological alterations by chronic exposure to low concentrations of carbon monoxide in highway workers of Mexico

Luis Fernando Díaz-López, Luis Cuauhtémoc Haro-García, Cuauhtémoc Arturo Juárez-Pérez, Guadalupe Aguilar-Madrid



Background. Workers of the automobile industry, service stations and those working in the streets, are in chronic contact to low concentrations of carbon monoxide and at risk to damage the cardiovascular, haematology and nervous systems.

Objective. Identify erythrocytosis and neuropsychological alterations in highway workers chronically exposed to low concentrations of CO.

Method. Cross-sectional study that included 72 workers of the Mexico-Puebla Highway cabins (guards); 60 cashiers and 12 workers in charge of the shift, in which socio-demographic, clinical and occupational variables were explored; haemoglobin(Hb), hematocrit (Htc) and carboxyhemoglobin (COHb) was determined in their blood, and it was applied the Carbon monoxide neuropsychological screening battery (CONSB). The workers who are in charge of the full shift integrated the less exposed to CO group, while the cashiers would shape the greater exposure group.

Results. In 49 workers, Hb: 18.1±1.9 mg/dL and Htc: 55.3±8.7 without significant differences between groups (p=0.82). The greater alteration was identified in the exposed group in the test of digit symbol (p= 0.012), trail-making part B (p= 0.002), and digit span (p=0.003); the test of blocks design resulted borderline (p=0.07).

Discussion and conclusion. The group with the highest exposure to CO had lower performance in visual perception, encoding, visual-motor perception and immediate memory. Therefore important to consider epidemiological surveillance workers to intervene in cases with abnormal tests. The perception of innocuousness of chronic exposure to CO in these workers must avoid.


Neuropsychological alterations; carboxyhemoglobin; CONSB; chronic occupational exposure; carbon monoxide