الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Lead is a widely used heavy metal with a broad industrial usage. It poses a significant health hazard in occupationally exposed populations.
The present study was carried out to investigate lead-induced oxidative stress and DNA damage. Moreover, to explore the potential impact of concomitant smoking.
The present study was conducted on 40 males working at automobile battery factory in Alexandria. They were chronically exposed to lead in their work environment. Twenty age-matched, non-exposed apparently healthy male subjects, served as a control group.
Half of both groups (lead-exposed workers and control group) were chosen to be smokers.
Each participant was interviewed and subjected to thorough history taking as well as laboratory investigations.
Blood samples were collected from each participant for determination of blood lead level by atomic absorption spectrophotometer, plasma malondialdehyde (MDA) levels by spectrophotometer and DNA fragmentation using agarose gel electrophoresis.
The age of lead-exposed workers in the current study ranged from 33 to 61 years, with a mean of 46.52 ± 7.73 years. The majority of them (75%) were above 40 years.
The duration of employment of lead exposed workers ranged from 2 up to 30 years with a mean of 18.74 ± 6.70 years. More than half of them (67.5%) were exposed for more than 20 years. All workers were categorized according to work department, as members of manufacturing department (75%) or administrative department (25%).
The majority of the participants in the present study were living in Alexandria and its suburbs.
In the present study, the majority of the smoker exposed workers were moderate and heavy smokers (35% and 35%). On the other hand, the majority of the smoker controls (70%) were moderate smokers.
The duration of smoking in the lead exposed workers ranged from 6 up to 40 years with a mean of 26.46 ± 9.61 years. No significant difference was detected regarding the duration of smoking, number of cigarettes smoked/day and smoking pack-year between the exposed workers and controls.
The medical complaints were mainly neurological and gastrointestinal manifestations. The most encountered complaints were fatigue (40%), numbness (37.5%) and constipation (38.5%). Additionally, history revealed that 15% of lead exposed workers were under treatment of hypertension.
The mean BLL in the exposed workers (33.65±8.53µg/dl) was significantly higher than in controls (14.65 ± 3.0µg/dl). There was significant positive correlation between BLL and age as well as duration of employment in lead exposed workers.
No significant difference was noticed between mean BLL among smoker and non smoker workers, nor among the symptomatic and asymptomatic exposed workers.
The personal protective equipments (PPE) were worn by only (25%) of the exposed workers. BLL was significantly lower in workers committed to the use of PPE than those who were not using them.
Regarding the oxidative stress biomarker, the present study showed that the mean level of MDA was significantly higher among the lead exposed workers compared to controls. Significant positive correlation was detected between MDA levels and age as well as duration of employment among lead exposed workers. On the other hand, no significant correlation was detected between MDA levels and age in the control group. Moreover, workers in manufacturing departments had significantly higher MDA levels than those in administrative departments.
Malondialdehyde levels were significantly higher in smokers than in non smokers in the lead exposed workers as well as in the control group. Although significant positive correlation was found between MDA levels and number of cigarettes smoked/day as well as smoking pack year, yet no significant correlation was noticed between MDA level and duration of smoking among the lead exposed workers.
No significant correlation was detected between MDA levels and number of cigarettes smoked/day, smoking pack year as well as duration of smoking in the control group. No significant difference was noticed between MDA levels among symptomatic and asymptomatic workers. Workers who used PPE showed significantly lower MDA levels than those who did not use them.
The study showed strong positive correlation between MDA levels and BLL among the lead exposed workers.
The multivariate linear regression was applied to estimate the factors affecting MDA levels among the exposed workers. It showed that BLL highly affect MDA level followed by smoking.
As regards the DNA fragmentation, the study revealed significantly higher frequency of DNA fragmentation among the exposed workers compared to controls (47.5% and 15% respectively).
The degree of DNA fragmentation was moderate in 15% of the exposed workers and mild in 32.5% of them. On the other hand, the fragmentation detected in the control group was only mild.
No significant correlation was detected between the degree of DNA fragmentation and age in the lead exposed workers and controls.
Positive significant correlation was detected between the degree of DNA fragmentation and duration of employment. In addition, DNA fragmentation was detected only in workers of the manufacturing departments.
The frequency of DNA fragmentation was significantly higher among smokers than in non smokers in the lead exposed group. DNA fragmentation was detected only in smokers of the control group (15%).
The study also showed significant effect of smoking on the degree of DNA fragmentation in lead exposed workers where non smokers showed only mild fragmentation.
Duration of smoking showed no significant effect on DNA fragmentation among the exposed workers. On the other hand, heavy smoking (high number of cigarettes smoked/day and smoking pack year) showed significant effect on the degree of DNA fragmentation. The lead exposed workers with moderate DNA fragmentation were all heavy smokers. Half of those with mild DNA fragmentation were moderate smokers.
In the control group, the study showed that duration of smoking, number of cigarettes smoked/day as well as smoking pack year showed no significant effect on the degree of DNA fragmentation.
No significant relation was observed between the presence of symptoms nor the use of PPE and the degree of DNA fragmentation.
The present study showed significant relation between BLL as well as MDA level and the degree of DNA fragmentation among the lead exposed workers. In the control group there was significant positive relation between MDA level and degree of DNA fragmentation.
The multivariate binary logistic regression and multivariate linear regression were applied to estimate the factors affecting the frequency and degree of DNA fragmentation among the exposed workers. They showed that MDA level, BLL followed by heavy smoking highly affect frequency and degree of DNA fragmentation.