Epidemiological-environmental study of lead acid battery workers. II. Acute effects of sulfuric acid on the respiratory system

Examining relationship between occupational acid exposure and oral health in workplace

Background

Acid mist can suspend in the air and enter the body via skin contact, the respiratory tract, or even oral intake, which pose various health hazards. Previous studies have shown that occupational exposure to acid mist or acidic solutions is a major risk factor for oral diseases. However, the findings are inconsistent and do not consider individual factors and lifestyles that may cause the same oral diseases. Therefore, we conducted a comprehensive oral health survey and collected detail information to confirm the effect of acidic solution exposure on worker’s oral health.

Methods

From 4 acidic solution factories, a total of 309 subjects (157 in control and 152 in exposed group) was enrolled. All participants competed oral examinations and self-report questionnaire, including the decayed, missing, and filled teeth (DMFT) index, community periodontal index (CPI), loss of attachment (LA) index, and tooth erosion. Multivariate logistic regression analysis was used to determine the association between the acidic solution exposure and oral health.

Results

The results showed that acid exposure was correlated with soft oral tissue injury rather than hard oral tissue in our survey. In the multivariate model (adjusted for sex, age, worked years, education level, mouthwash use, dental floss use, tooth brushing, mask use, smoking, drinking, chewing areca and dietary habits with acidic foods), significant relationships of acid exposure with LA score were observed (OR = 2.32, 95% CI 1.03–5.26). However, the presence of acid exposure was not significantly associated with tooth erosion, DMFT, and CPITN.

Conclusion

Our study highlighted that occupational acid exposure was an independent risk factor for periodontal health, especially LA. It is important to strengthen occupational hazard control, educate workers on oral disease and related factors, and raise the awareness of oral hygiene.

The effect of the use of NP305 masks in improving respiratory symptoms in workers exposed to sulfuric acid mists in plating and pickling units

Background:

Plating and pickling processes are the most effective ways for increasing the strength of metal structures, and workers in these units are exposed to various contaminants, including acid mists. The aim of this study was to investigate the effect of protective masks in decreasing the respiratory symptoms and the aerobic capacity of workers that are exposed sulfuric acid mist.

Methods:

This interventional study was based on National Institute for Occupational Safety and Health (NIOSH) standard 7903 in which silica gel tubes are used for sampling the air in plating and pickling units for eight hours. After the samples were acquired and prepared, they were analyzed by ion chromatography and were compared with the American Conference of Governmental Industrial Hygienists (ACGIH) exposure limits. Respiratory symptoms were evaluated among two sets of test subjects, i.e., those who used NP305 masks in the workplace and those who did not use the mask.

Results:

The results showed that the concentration of sulfuric acid mist in the plating units was greater than the exposure limits, and concentrations at this level can cause an increase in symptoms related to irritation of the airway and a slight decrease in respiratory capacity. In this study, smoking had no significant effect on the severity of pulmonary dysfunction.

Conclusion:

The results indicated that the use of an NP305 mask is effective for decreasing symptoms resulting from exposure to sulfuric acid mist and improving respiratory capacity.

Clinical and histopathological changes of the nasal mucosa induced by occupational exposure to sulphuric acid mists

AIMS

To assess potential alterations of the nasal mucosa by clinical and histopathological evaluation of workers exposed to sulphuric acid mists at anodising plants, correlating the findings with duration of exposure and sulphuric acid concentrations in the air, and comparing them with a control group.

METHODS

Fifty two workers from five plants underwent a clinical evaluation (standard questionnaire, clinical, and ear, nose, and throat examination including nasal endoscopy). For the histopathological study, 20 of the 52 subjects (study group) were randomly selected, as well as 11 unexposed subjects (control group), matched by sex, age, and smoking habits. Nasal biopsy specimens were obtained from the anterior septum mucosa and the anterior curvature of the middle turbinate in each individual. A total of 56 nasal mucosa specimens (37 in the study group and 19 in the control group) were evaluated with regard to normal respiratory epithelium or metaplastic epithelium, atypia or dysplasia, and alterations of the lamina propria.

RESULTS

The histopathological study revealed squamous metaplasia in 29 (79%) and atypia in 13 (35%) of the 37 study group samples. No association was found between exposure duration and the clinical and histopathological variables, but a significant association was found between sulphuric acid concentrations higher than 200 micro g/m(3) and pale mucosal patches and ulcerations in the exposed subjects. Logistic regression analysis showed that the exposed subjects had a fivefold risk of developing atypia compared with the unexposed subjects.

CONCLUSIONS

Workers exposed to sulphuric acid mists presented with a high incidence of nasal symptoms, and macroscopic and microscopic changes of the nasal mucosa, including squamous atypia and dysplasia. The risk for these histopthological lesions increased with higher sulphuric acid concentrations in the air, revealing an exposure-response relation.

Epidemiological-environmental study of diesel bus garage workers: acute effects of NO2 and respirable particulate on the respiratory system

Personal samples of nitrogen dioxide (NO2) and respirable particulate (RP) were collected over the shift on 232 workers in four diesel bus garages. Response was assessed by an acute respiratory questionnaire and before and after shift spirometry. Measures of exposure to NO2 and RP were associated with work-related symptoms of cough; itching, burning, or watering eyes; difficult or labored breathing; chest tightness; and wheeze. The prevalence of burning eyes, headaches, difficult or labored breathing, nausea, and wheeze experienced at work were higher in the diesel bus garage workers than in a comparison population of battery workers, while the prevalence of headaches was reduced. Mean reductions in forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), peak flow, and flows at 50 and 75% of FVC were not obviously different from zero. There was no detectable association of exposure to NO2 or respirable particulate and acute reductions in pulmonary function. Workers who often had respiratory work-related symptoms generally had a slightly greater mean acute reduction in FEV1 and FEF50 than did those who did not have these symptoms, but these differences were not statistically significant.

Epidemiological-environmental study of lead acid battery workers. III. Chronic effects of sulfuric acid on the respiratory system and teeth

The effects of long-term exposure to sulfuric acid mist on the teeth and respiratory system were studied in 248 workers in five plants manufacturing lead acid batteries. The prevalence of cough, phlegm, dyspnea, and wheezing as determined by questionnaire were not associated with estimates of cumulative acid exposure. There was only one case of irregular opacities seen on the chest radiographs. There was no statistically significant association of reduced FEV1, peak flow, FEF50, and FEF75 with acid exposure although the higher exposed group had lower mean values. FVC in the high exposure group showed a statistically significant reduction compared to the low exposure group, but there was no significant association when exposure was analyzed as a continuous variable. The ratio of observed to expected prevalence of teeth etching and erosion was about four times greater in the high acid-exposure group. The earliest case of etching occurred after 4 months exposure to an estimated average exposure of 0.23 mg/m3 sulfuric acid.