Effect of exposure to occupational noise and shift working on blood pressure in rubber manufacturing company workers.

This study aimed to assess the relationship between shift working and occupational exposure to noise with blood pressure (BP). The study was carried out in a rubber manufacturing company in 2010. Demographic, medical and occupational information for carrying out the study were collected through direct interview. All 331 under study workers were divided into four groups according to work shift and noise exposure severity, from non-noise exposed day time workers (Group 1) to noise exposed shift workers (Group 4). Finally, systolic and diastolic blood pressure levels were compared among these four groups. The results of this study showed that there was a significant difference between average systolic and diastolic BP and hypertension (HTN) frequency in the four groups (p<0.05). The highest rate of HTN and mean systolic and diastolic BP were observed among shift workers who were exposed to noise higher than permissible limit (Group 4). Also the results of logistic regression analysis showed that there was a significant relationship between simultaneous exposures to noise more than the permitted limit and shift work with HTN (p<0.05). The results of our study showed that shift working and simultaneous exposure to noise have an additive effect on occurrence of HTN. It is recommended that during periodic physical examinations of noise exposed shift workers, assessment of the cardiovascular system and BP should be done as well as the auditory system.