A pilot survey of blood lead levels in various types of workers in the United Arab Emirates

Assessement of Blood Lead and Cadmium Levels in Occupationally Exposed Workers of Jodhpur, Rajasthan

In spite of the established knowledge regarding their toxicities, occupational exposure to heavy metals like lead and cadmium still continues because of their wide distribution in environment. Due to lack of awareness, most of the workers usually eat, smoke, drink at their workplace which may aggravate the metal exposure. The present study was planned to assess the blood levels of lead and cadmium in occupationally exposed workers of Jodhpur (India). A total of 110 individuals working in different industrial set ups (furniture, metal handicraft, welders) of Jodhpur district (exposed group), aged between 20 and 60 years and 97 apparently healthy people (controls) with no history of occupational heavy metal exposure aged between 25 and 60 were recruited. Details of personal habits and demographics were recorded by means of self-developed questionnaire. 5 ml of whole blood was drawn from every individual. Metal levels were measured by graphite furnace atomic absorption spectrophotometer. Statistical analysis was done using GraphPad Prism Software. Results showed that Blood Lead Level and Blood Cadmium Level (CdB) were significantly higher in the exposed group as compared to the non-exposed group. Significant age and gender-based differences were found in terms of blood cadmium levels but no such difference was observed in case of blood lead. The study also revealed that higher blood levels of these metals in workers are influenced by their occupational practices, lack of protection against workplace environment pollutants, thus increasing their susceptibility to metal toxicity.

Exposure to lead and its effect on sleep quality and digestive problems in soldering workers

Some studies show that exposure to lead affects sleep quality and causes digestive disorders. The aim of this study was to evaluate the quality of sleep and digestive disorders in solderers exposed to lead. In a cross-sectional study, the occupational exposure of 40 soldering workers to lead fume and their blood lead levels were measured in the electronics industry of Neyshabur city, according to standard methods. The sleep quality of workers was measured by the Pittsburgh Sleep Quality Index (PSQI) questionnaire and their digestive disorders were recorded in a checklist. This study showed that 67.5% of subjects had poor sleep quality. There was a significant relation between sleep quality, air lead (p = 0.02), and blood lead (p = 0.03). Bad sleep quality was 2.4 times higher in subjects exposed to lead above the threshold (p = 0.03). 92.5% of the population under study suffered from at least one digestive disorder. Digestive disorders such as hiccupping (85%) and nausea (67%) were more common among the workers, and their odds was 3.09 and 2.00 times higher in workers exposed to lead above the threshold, compared with others. Bad sleep quality and gastrointestinal disorders were prevalent among workers exposed to lead. The results of this study confirm the need for further research about the side effects of lead on humans. It also clarifies the need for a revision in the recommended occupational exposure level for lead.

The effect of environmental lead exposure on human health and the contribution of inflammatory mechanisms, a review

Lead (Pb) pollution has been considered as a major threat for human health due to induction of inflammatory cascades in various tissues. The aim of present review is to summarize the literature on the effects of lead exposure on respiratory, neurologic, digestive, cardiovascular and urinary disorders and the role of inflammation as an underlying mechanism for these effects. Various databases such as ISI Web of Knowledge, Medline, PubMed, Scopus, Google Scholar and Iran Medex, were searched from 1970 to November 2017 to gather the required articles using appropriate keywords such as lead, respiratory disorders, neurologic disorders, digestive disorders, cardiovascular disorders, urinary disorders and inflammation. Disorders of various body systems and the role of inflammation due to lead exposure has been proven by various studies. These studies indicate that lead exposure may cause respiratory, neurologic, digestive, cardiovascular and urinary diseases. The results were also indicated the increased inflammatory cells and mediators due to lead exposure including cytokines and chemokines due to lead exposure which suggested to be the cause various organ disorders.

Lead (Pb) Exposure Enhances Expression of Factors Associated with Inflammation

The human immune system is constantly exposed to xenobiotics and pathogens from the environment. Although the mechanisms underlying their influence have already been at least partially recognized, the effects of some factors, such as lead (Pb), still need to be clarified. The results of many studies indicate that Pb has a negative effect on the immune system, and in our review, we summarize the most recent evidence that Pb can promote inflammatory response. We also discuss possible molecular and biochemical mechanisms of its proinflammatory action, including the influence of Pb on cytokine metabolism (interleukins IL-2, IL-4, IL-8, IL-1b, IL-6), interferon gamma (IFNγ), and tumor necrosis factor alpha (TNF-α); the activity and expression of enzymes involved in the inflammatory process (cyclooxygenases); and the effect on selected acute phase proteins: C-reactive protein (CRP), haptoglobin, and ceruloplasmin. We also discuss the influence of Pb on the immune system cells (T and B lymphocytes, macrophages, Langerhans cells) and the secretion of IgA, IgE, IgG, histamine, and endothelin.

Blood lead levels, pulmonary function and agility in Polish schoolchildren

BACKGROUND

Reduced vital capacity (VC) and forced vital capacity (FVC) are associated with lead (Pb) exposure.

AIM

The objective of this study is to analyse the effects of Pb on FVC and the shuttle run performance.

SUBJECTS AND METHODS

Data were available for 184 male and 189 female Polish schoolchildren aged 10-15 years. Regression analysis was performed of shuttle run performance (dependent) on Pb and FVC.

RESULTS

Shuttle run time increased by 1.75 (± 0.77) and 1.97 (± 0.77) seconds for each 10 µg/dL increase in Pb blood among males and females, respectively. Higher shuttle run times indicate poorer performance. Average unadjusted blood Pb level in the sample was 5.27 μg/dL (± 0.19 SE) and 3.82 μg/dL (± 0.10 SE), respectively. Path analysis was used to assess the association of Pb level with shuttle run time. Blood Pb had a significant negative effect on VC (B= -13.60 ± 3.28 [SE], p < 0.0001) and FVC (B = -13.08 ± 3.27, p < 0.0001). FVC had a small but significant effect on shuttle run time (B = -0.04 ± 0.007, p < 0.0001). Pb had a significant effect on the residual of shuttle run time among males (B = 1.59 ± 0.75, p < 0.03) and females after the effect of FVC was removed (B = 1.49 ± 0.73, p < 0.04).

CONCLUSIONS

Thus, Pb had direct and indirect effects that increased shuttle run time, i.e. negatively affected performance.

Inhaled lead affects lung pathology and inflammation in sensitized and control guinea pigs

The association between lead exposure and respiratory diseases including asthma is controversial. Some studies indicate that exposure to environmental lead pollution may cause asthma; however, there is not sufficient data in this regard. The effect of lead on lung pathological findings and serum inflammatory mediators in sensitized and non-sensitized guinea pigs exposed to inhaled lead was examined. Eleven animal groups including control, sensitized, three groups of non sensitized animals, three groups during sensitization, and three groups after sensitization exposed to aerosol of three lead concentrations (n = 6 for each group) were studied. Serum inflammatory mediators levels and lung pathological changes were evaluated. All pathological changes and serum ET-1, EPO, NO levels were significantly higher in the sensitized and non sensitized animals exposed to lead than control group (p < 0.05 to p < 0.001). There was no significant difference between non sensitized groups exposed to high lead concentration and sensitized group. Serum inflammatory mediators levels and pathological findings in sensitized groups exposed to lead both during and after sensitization were significantly higher than sensitized non exposed group (p < 0.05 to p < 0.001). The data of exposed animals to high lead concentration were significantly higher than those of medium and low concentrations; those of medium concentration were also higher than low concentration (p < 0.05 to p < 0.001). In summary, the present study indicates that exposure to inhaled lead is able to induce respiratory changes similar to asthma. In addition, the results indicated that exposure to environmental lead is able to aggravate asthma severity both during development of asthma or after its manifestation.

Early Blood Lead Levels and Sleep Disturbance in Preadolescence

STUDY OBJECTIVES

Little is known about the effect of lead exposure on children's sleep. This study examined the association between blood lead levels (BLL) and sleep problems in a longitudinal study of children.

SETTING

Four community-based elementary schools in Jintan City, China.

PARTICIPANTS

1,419 Chinese children.

MEASUREMENT AND RESULTS

BLL were measured when children were aged 3-5 y, and sleep was assessed at ages 9-13 y. Sleep was assessed by both parents' report, using the Children's Sleep Habits Questionnaire (CSHQ), and children's report, using an adolescent sleep questionnaire. A total of 665 children with complete data on BLL and sleep at both ages were included in the current study. Mean age of the sample at BLL assessment was 4.74 y (standard deviation [SD] = 0.89) and at sleep assessment was 11.05 y (SD = 0.88). Mean BLL was 6.26 μg/dL (SD = 2.54). There were significant positive correlations between BLL and 3 CSHQ subscales: Sleep onset delay (r = 0.113, P < 0.01), sleep duration (r = 0.139, P < 0.001), and night waking (r = 0.089, P < 0.05). Excessive daytime sleepiness (EDS) (26.1% versus 9.0%, P < 0.001) and use of sleeping pills (6.5% versus 1.8%, P = 0.03) were more prevalent in children BLL ≥ 10.0 μg/dL than in those children BLL < 10.0 μg/dL. After adjusting for demographics, BLL ≥ 10.0 μg/dL was significantly associated with increased risk for insomnia symptoms (odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.03-3.95) and EDS (OR = 2.90, 95% CI = 1.27-6.61).

CONCLUSION

The findings indicate that elevated blood lead levels in early childhood are associated with increased risk for sleep problems and excessive daytime sleepiness in later childhood.

Lead exposure and increased food allergic sensitization in U.S. children and adults

BACKGROUND

Whether blood lead levels are associated with sensitization to food allergens in adults and children is unclear. Prior studies have shown that exposure to lead is associated with atopic sensitization and modulation of several cytokines (eg, interleukin [IL]-12, IL-10, interferon [IFN]-γ, and IL-4 production) and with T-cell dysregulation and bias toward T helper 2 (Th2) activity. The objective of this work was to assess whether exposure to lead is independently associated with allergic symptoms and sensitizations in a large nationally representative sample of children and adults.

METHODS

We studied 2712 children and 4333 adults enrolled in the 2005-2006 cycle of the National Health and Nutritional Examination Surveys (NHANES). Participants were tested for serum-specific immunoglobulin E (IgE) levels to food allergens as well as blood lead levels. Food allergens tested included shrimp, egg, peanut, and milk. Logistic regression models adjusted for demographic factors, body mass index, history of asthma, smoking, housing characteristics, and current exposure to animals in the home, to assess the association of blood lead levels with sensitization to food allergens.

RESULTS

Median (interquartile range [IQR]) for serum blood was 0.87 μg/L (0.61 to 1.31) in children and 1.48 μg/L (0.92 to 2.34) in adults. At baseline, 672 (24.7%) of children participants and 719 (16.6%) of adult participants tested positive for increased sensitization to food allergens. A 2-fold increase in blood lead levels in adult participants was associated with increased sensitization to food allergens (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.02 to 1.22). Blood lead was not associated with sensitization to food allergens among pediatric participants (OR, 0.95; 95% CI, 0.82 to 1.10).

CONCLUSION

Exposure to lead was associated with increased odds of sensitization to food allergens in adult but not children participants.

Elevated blood lead levels among unskilled construction workers in Jimma, Ethiopia

Background

No study has been carried out to assess the blood lead levels of workers or the contribution of common workplace practices to lead exposure in Ethiopia. This study was carried out to assess the blood lead levels of female and male laborers in the construction sector in Jimma town, Ethiopia.

Method

A cross-sectional study on the blood lead levels of 45 construction workers was carried out in the town of Jimma. The t-test, analysis of variance, the Kruskal-Wallis, Mann–Whitney and odds ratio tests were used to compare mean blood lead levels and to investigate the associations between specific job type, use of self-protection device, sex, service years and occurrence of non-specific symptoms with BLLs.

Results

The mean blood lead level of the exposed group (40.03 ± 10.41 μg/dL) was found to be significantly greater than that of the unexposed group (29.81 ± 10.21 μg/dL), p = 0.05. Among the exposed group female workers were found to have higher mean blood lead level (42.04 ± 4.11 μg/dL) than their male colleagues (33.99 ± 3.28 μg/dL). Laborers who were regularly using self-protection devices were found to have significantly lower blood lead levels than those who were not using.

Conclusion

The blood lead levels of construction workers in Jimma town are considerably high with a range of 20.46 – 70.46 μg/dL and the workers are in danger of imminent lead toxicity. More endangered are female construction workers who are bearers of the future children of the country and the issue requires urgent attention.

Inhaled lead exposure affects tracheal responsiveness and lung inflammation in guinea pigs during sensitization

Total and differential white blood cells (WBC), and cytokines, levels in serum were examined in guinea pigs exposed to inhaled lead acetate. Different groups of guinea pigs including: control (group C), sensitized group (group S), and exposed animals to aerosol of three lead concentrations during sensitization (n = 6 for each group) were studied. Total and differential WBC counts of lung lavage, serum cytokine (IFNγ and IL-4), levels and tracheal responsiveness to methacholine and ovalbumin were measured. All measured values were significantly increased except for IFNγ/IL-4 ratio which was significantly decreased in nonexposed sensitized and those exposed to all lead concentrations compared to control group (p < 0.05 to p < 0.001). Most measured values in animals exposed to higher lead concentration were also significantly higher than group S except for tracheal responsiveness to methacholine and lymphocyte count. Lead concentration significantly increased in lung tissues of animals exposed to all three lead concentrations (p < 0.001 for all cases). These results showed that lead exposure during sensitization can induce greater increase in tracheal responsiveness, total WBC, eosinophil, neutrophil, and basophil counts as well as serum level of IL-4. It can also cause a decrease in lymphocyte count, IFNγ level, and IFNγ/IL-4 ratio especially in its high concentration. Therefore inhaled lead exposure may cause increased severity of asthma during development of the disease.

The effect of lead exposure on tracheal responsiveness to methacholine and ovalbumin, total and differential white blood cells count, and serum levels of immunoglobulin E, histamine, and cytokines in guinea pigs

The effect of exposure to inhaled lead acetate in guinea pigs was evaluated. The present study comprised of five groups of guinea pigs including control (C), sensitized to ovalbumin (OA; S) and three groups exposed to 0.1, 0.2, and 0.4 M inhaled lead (Pb; n = 6 for each group). Tracheal responsiveness to methacholine and OA, total and differential white blood cells (WBCs) count in lung lavage, serum levels of cytokines (interferon γ (IFN-γ) and interleukin 4 (IL-4)), histamines, and immunoglobulin E (IgE), and Pb concentration in lung were measured. Tracheal responsiveness to methacholine, OA, total and differential WBC types as well as IL-4, IFN-γ, histamine, and IgE were significantly increased but IFN-γ/IL-4 were significantly decreased in sensitized animals as well as those exposed to high Pb concentrations when compared with the control group (from p < 0.05 to p < 0.001). In addition, there was not a significant difference in most measured values between animals exposed to high Pb concentration and group S. The Pb concentration in lung tissues of animals exposed to all three Pb concentrations was significantly higher than that of group C (p < 0.001 for all cases).These results showed that inhaled lead acetate exposure can induce lung inflammatory changes similar to sensitized animals. Therefore, exposure to environmental Pb pollution may cause asthma-like changes.

The effect of lead acetate on oxidative stress and antioxidant status in rat bronchoalveolar lavage fluid and lung tissue

Despite the wide spread of lead environmental pollution, the effect of this heavy metal on respiratory disease was not shown yet. In respect to increased oxidative stress is an important mechanism in the pathogenesis of respiratory disease, the present study was designed to examine the association between lead toxicity and lung disease via measuring oxidative stress biomarkers in bronchoalveolar lavage fluid (BALF) and lung tissue of rat. For this aim, 32 rats were divided into the following groups of eight animals each: control, three lead tested (received lead acetate in the drinking water for a period of 14 d at concentrations of 250, 500 and 1000 ppm) groups. At the end of the 2 week period, malondialdehyde (MDA), nitric oxide (NO) and reduced glutathione (GSH) contents were measured to assess free radical activity in the BALF and lung tissue. Superoxide dismutase (SOD) was also determined. A significant dose-dependent increase in the BALF supernatant and lung homogenate levels of MDA and NO with decrease GSH level and SOD activity were observed in the lead-treated groups compared with the control group (p < 0.05). Thus, lead acetate may be contributed to respiratory disorders via increased oxidative stress.

Tracheal responsiveness to methacholine and ovalbumin; and lung inflammation in guinea pigs exposed to inhaled lead after sensitization

The association between lead exposure and asthma is controversial. The effect of inhaled lead acetate on lung inflammation, tracheal responsiveness and immune components in guinea pigs after sensitization was examined in this study. Five groups of guinea pigs were randomly allocated to control (group C), sensitized (group S), and three test groups exposed to inhaled lead concentrations 0.1, 0.2 and 0.4M Pb after sensitization (n=6 for each group). The measured variables included tracheal responsiveness to methacholine and ovalbumin (OA); total and differential white blood cells (WBC) counts of lung lavage; serum cytokine levels (IFN-γ and IL-4); and lead concentration in lung tissue. Tracheal responsiveness to methacholine and OA; total and differential WBC counts; IL-4 and IFN-γ were significantly increased in sensitized animals compared to control group (p<0.05 to p<0.001). However, the ratio of IFN-γ/IL-4 were significantly decreased in group S (p<0.05). In addition, all measured parameters in animals exposed to highest lead concentration and most of them in animals exposed to medium lead concentration were significantly higher than group S, except for the IFN-γ and IFN-γ/IL-4 ratio, which were significantly decreased (p<0.05 to p<0.001). The lead concentration in lung tissues of all test animals was significantly higher than that of group C (p<0.001 for all groups). These results showed that lead acetate exposure can cause further increase in tracheal responsiveness to methacholine and OA, total and differential WBC count and IL-4, IFN-γ and IFN-γ/IL-4 ratio. Therefore, environmental exposure to lead may aggravate the severity of asthma.

Respiratory symptoms and pulmonary function testes in lead exposed workers

Background

The exposure to noxious agwents such as lead my cause lung disorders.

Objectives

In the present study, pulmonary function tests and self-reported respiratory symptoms in lead exposure workers were compared with matched control subjects.

Materials and Methods

The frequency of respiratory symptoms were evaluated in a sample of 108 lead exposure workers and 100 control subjects with similar age using a questionnaire including questions on respiratory symptoms in the past year. Pulmonary function tests (PFT) were also measured in lead exposure workers and in controls.

Results

Most lead exposure workers (63%) reported work-related respiratory symptoms. Chest tightness (26%), cough (17%) and sputum (16%) were the most common symptoms and only 6% of lead exposure workers reported wheezing (P < 0.001 for all case except wheezing). Most PFT values were also significantly reduced among lead exposure workers (P < 0.05 to P < 0.001 except MEF75, MEF50, MEF25, and MMEF. The lead concentration in urine and serum of lead exposure workers were significantly higher than control (P < 0.001 for both cases).

Conclusions

These results showed that c lead exposure workers have higher frequencies of respiratory symptoms higher serum and urine lead concentration but lower PFT values.

Occupational lead exposure among automotive garage workers - a case study for Jimma town, Ethiopia

Background

In Ethiopia, although there are numerous small-scale and medium industries which use lead-based raw materials that may pose health risks to workers, there are no workplace regulations for lead exposure. Moreover, there are no studies carried out on the blood lead levels (BLLs) of workers or on the contribution of common workplace practices to lead poisoning.

Method

A cross-sectional study on the BLLs of 45 automotive garage workers and 40 non-garage workers was carried out in the town of Jimma, Ethiopia. In addition to BLL analysis, data on some risk factors such as smoking, and chewing ‘khat’ (the leaves of Catha adulis) were gathered through structured questionnaires and interviews and data analysis was performed using SPSS (version 16). The t-test was used to compare mean BLLs of study groups. The analysis of variance (ANOVA), Kruskal-Wallis, Pearson chi-square and odds ratio tests were used to investigate the associations between specific job type, smoking and/or ‘khat’ chewing, service years and occurrence of non-specific symptoms with BLLs.

Results

The mean BLL of the automotive-garage workers was found to be significantly greater than that of the controls. The BLLs of all the lead-exposed individuals were found to be over 10 μg/dL, and 53% of them had BLLs ranging 12 – 20 μg/dL, with the remaining 47% having over 20 μg/dL. The BLL of the workers increased with the duration of working in an automotive garage.

Individuals involved in manual car painting comprise a larger percentage (58%) of those with the highest BLLs (≥ 20 μg/dL). Lead accumulation in individuals who chew ‘khat’ in the work place was found to be faster than in those who are not used to chewing ‘khat’. ‘Khat’ is an evergreen shrub native to tropical East Africa, with dark green opposite leaves which are chewed when fresh for their stimulating effects.

Conclusion

The findings of the study have clearly demonstrated that the BLLs of automotive-garage workers in Jimma town are considerably high with a range of 11.73 – 36.52 μg/dL and the workers are in danger of impending lead toxicity. The BLLs of the workers are influenced by their occupational practices, chewing Catha adulis leaves at the workplace, and the time spent working in an automotive garage.

Occupational lead exposure: blood lead levels of apprentices in Bursa, Turkey

The aim of this cross-sectional study was to compare the blood lead levels of apprentices working in lead-related industries with those of non-apprentice controls and to evaluate the influence of such occupational exposure. The study was conducted between October 2004 and June 2005 in Bursa, Turkey. Subjects included 231 apprentices and 252 male controls, age ranging from 14-19 yr old. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze blood lead levels. The overall mean blood lead level was 3.62 microg/dl (95% CI 3.39-3.85), the apprentice mean was 4.99 microg/dl (95% CI 4.60-5.38), and the control group mean was 2.37 microg/dl (95% CI 2.22-2.51). The blood lead level of apprentices was significantly higher than that of controls (p<0.05). Results show that occupational exposure increases the blood lead levels of apprentices, although the impact on their immediate health is low. Measurement of blood lead levels of apprentices should be taken periodically, and a regular medical surveillance program should be established.

Blood lead levels and increased bronchial responsiveness

The immune system is one of the targets most sensitive to lead toxicity, and the association between lead exposure and serum immunoglobulin E (IgE) has been published. Recent studies also reported that lead caused the development of IgE-mediated allergy. To investigate whether blood lead levels contribute to other allergic conditions, we examined the effect of blood lead on bronchial responsiveness (BR) in the general population. We performed a cross-sectional study with adults aged 19 to 58 years in a Korean community. Blood lead level and the methacholine provocation test were performed. The overall mean blood lead level was 2.9 microg/dl, and the mean BR index was 1.14. The percent of subjects with clinically diagnosed asthma was 21 (4%) and there was no difference in blood lead level with and without asthma. In the multiple regression model, the elevation of blood lead level was related to the increase of BR after adjusting for age, sex, height, smoking status, and the presence of asthma. Blood lead level was significantly associated with increased BR that came from the elevation of the IgE level with lead exposure. Lead may contribute to the increase of asthma and other allergic conditions.

Blood lead level and risk of asthma

Asthma and lead poisoning are prevalent among urban children in the United States. Lead exposure may be associated with excessive production of immunoglobulin E, possibly increasing asthma risk and contributing to racial disparities. The objective of this study was to examine racial differences in the association of blood lead level (BLL) to risk of developing asthma. We established and followed a cohort prospectively to determine asthma onset, using patient encounters and drug claims obtained from hospital databases. Participants were managed care enrollees with BLL measured and documented at 1-3 years of age. We used multiple variable analysis techniques to determine the relationship of BLL to period prevalent and incident asthma. Of the 4,634 children screened for lead from 1995 through 1998, 69.5% were African American, 50.5% were male, and mean age was 1.2 years. Among African Americans, BLL > or = 5 and BLL > or = 10 microg/dL were not associated with asthma. The association of BLL > or = 5 microg/dL with asthma among Caucasians was slightly elevated, but not significant [adjusted hazard ratio (adjHR) = 1.4; 95% confidence interval (CI), 0.7-2.9; p = 0.40]. Despite the small number of Caucasians with high BLL, the adjHR increased to 2.7 (95% CI, 0.9-8.1; p = 0.09) when more stringent criteria for asthma were used. When compared with Caucasians with BLL < 5 microg/dL, African Americans were at a significantly increased risk of asthma regardless of BLL (adjHR = 1.4-3.0). We conclude that an effect of BLL on risk of asthma for African Americans was not observed. These results demonstrate the need for further exploration of the complex interrelationships between race, asthma phenotype, genetic susceptibilities, and socioenvironmental exposures, including lead.