Background: The purpose of this study is to assess whether occupational exposure to low doses of nickel (Ni) present in urban air can cause alterations in the concentration of plasma testosterone in workers of the Municipal Police of a large Italian city assigned to different types of outdoor tasks.
Methods: 359 male subjects were included in the study and divided on the basis of job, age, length of service and smoking habits. The dosage of the atmospheric Ni was performed by personal dosimetries on a sample of the workers included in the study. For each worker included in the study the dosage of whole blood Ni and of the plasma testosterone was carried out. The total sample was subjected to the independent-samples T-test and the Mann-Whitney U test for variables with 2 modes (smoking cigarette) and the ANOVA test and the Kruskal Wallis test for variables with more than 2 modes (age, length of service and job function). The correlation of Pearson with p at 2 wings between the variables was evaluated in the total sample and after subdivision on the basis of smoking and on the basis of the job. After taking into account the major confounding factors the multiple linear regression was performed on the total sample and after breakdown by tasks.
Results: The correlation between the values of urinary Ni and the values of plasma testosterone on the total sample and for all classes of subdivision was found constantly negative. These results were confirmed by multiple linear regression, which indicated the Ni as the only significant variable that can contribute to the alterations of the testosterone.
Conclusions: Based on the results, the Authors suggest that occupational exposure to low doses of Ni present in the urban environment is able to influence some lines of the hypothalamic-pituitary-gonadal axis in exposed workers.