Biochemical effects of lead exposure on oxidative stress and antioxidant status of battery manufacturing workers of Western Maharashtra, India

Selenium and vitamin E ameliorate lead acetate-induced hepatotoxicity in rats via suppression of oxidative stress, mRNA of heat shock proteins, and NF-kB production

BACKGROUND

Lead exposure results in a terrible rise in heat shock protein levels.

OBJECTIVE

This research was conducted to look at the effects of lead poisoning on heat shock response, oxidative stress, and inflammatory markers in albino rats, as well as the power of selenium and vitamin E to resist lead toxic effects.

METHODS

Eight groups of albino rats are used. Each group contained six rats where the first group represented the negative control, and the other groups were treated with olive oil, vitamin E, selenium, lead, (vitamin E + lead), (selenium + lead), and (vitamin E + selenium + lead). All the treatments lasted for 28 days. Then, the mRNA expression of interested heat shock proteins (HSP90, HSP70, and HSP60) was assessed. For oxidative stress disruption, we investigated nitric oxide (NO) and malondialdehyde (MDA) content, and enzymatic and non-enzymatic antioxidants activity respectively in rat livers.

RESULTS

our results revealed the synergetic protective effect of the combination of two antioxidants (vitamin E and selenium) against lead poising. This was clear in regulating HSPs expression, inflammatory markers, glucose, lipid profile, liver functions, and antioxidant enzymes more than the treatment with one antioxidant.

CONCLUSION

Pb is a toxic material that can induce HSPs and inflammatory markers expression. Selenium and vitamin E can give excellent effects in ameliorating Pb toxicity when used together.

"Blood lead level among battery factory workers in low and middle-income countries: Systematic review and meta-analysis"

Introduction

Lead is one of the most health-hazardous causes of acute and chronic poisoning at workplaces. A limited study was conducted on the blood lead concentration among battery factory workers in low and middle-income countries. Therefore, this study will improve workplace health and safety conditions of workers in this sector and serve as baseline data for further studies in this segment of the working setup.

Objective

This review aims to identify the pooled mean blood lead level among battery factory workers in low and middle-income countries.

Methods

The search methods considered the following electronic bibliographic databases: google scholar, PubMed, and other gray literature. A funnel plot and Begg test were used to see the publication bias. The heterogeneity of studies was checked using I-square statistics with a cut of point 75% and the Joanna Briggs Institute (JBI) quality assessment tool was applied to ensure the quality of the included articles. A random-effect model was applied to pool the blood lead level intoxication. The sub-group analysis and Meta-regression analysis were conducted by country and year of publication to control heterogeneity and to show variation. We included the articles published from 2000 to 2021 year in the English language.

Results

Through the search strategies, 135 articles were identified and 43 full-text articles were selected for evaluation, and finally, eighteen (18) articles fit the inclusion criteria. From the 18 studies included in the meta-analysis, the mean pooled blood lead level of workers was 37.996 μg/dl (95% CI: 30.680-45.312) which is higher than the threshold limit value set by American conference of governmental industrial hygienists (20 μg/dl). In subgroup analysis by year in the random effect model, the pooled mean of blood lead level from 2006 to 2011= 43.20 μg/dL (35.91-50.50), 2012-2015 = 37.78 μg/dl (25.23-50.29), and 2016-2020 = 36.53 μg/dl (19.44-53.62).

Conclusions

This review showed that the pooled mean blood lead level of workers exposed to lead battery factories was (37.996 μg/dl) which is above the threshold limit value (20 μg/dl). Therefore, attention should be given by employers, government, and researchers to improve the health of working populations exposed to lead exposure in low and middle-income countries through the provision of occupational health and safety services like periodical medical checkups, treatments, and provision of training and adequate and appropriate personal protective equipment.Systematic review registration: Identifier: CRD42022322827.

Metal biomonitoring using fractioned dust to investigate urinary and oxidative stress biomarkers among occupationally exposed chromite mine workers

Exposure to heavy metals has been associated with the generation of reactive oxygen species (ROS) among exposed individuals in occupational and environmental settings. Dust is considered a significant contributor to airborne metal exposure, and previous data suggest that their levels in dust may vary based on its particle sizes. However, no biomonitoring study has been reported so far to address the metal-induced oxidative stress using different dust fractions, particularly in occupational settings. We designed a systematic cross-sectional study involving 110 chromite mine workers stratified into loaders (n = 28), extractors (n = 47) and operators (n = 35), and controls (n = 30) to find out the association between dust-bound metal exposure and oxidative stress using urinary creatinine-adjusted metal level as a biomarker of metal exposure. Results suggested elevated urinary levels of Cr 51.34 ± 8.6 along with Pb 34.29 ± 4.39, Cd 21.1 ± 2.6, and Ni 18.98 ± 3.01 µg/g creatinine in exposed (extractor group) workers. Correlating metal levels with oxidative stress revealed elevated malondialdehyde (MDA) levels of 62.28 ± 5.52 nM/dl among the extractors showing high levels of lipid peroxidation. Furthermore, blood superoxide dismutase (SOD) was also found significantly correlated (P = 0.000) with urinary toxic metal levels among exposed workers. We report the association between metal exposure and oxidative stress in exposed mining workers that may give rise to workers' susceptibility towards genetic and non-genetic health implications. The current study emphasized on the need for exposure control measures in the chromite ore mining activity areas.

Blood lead concentrations in children with iron deficiency anemia: a systematic review and meta-analysis

Iron deficiency is the most common nutritional disorder detrimental to the behavior, cognitive performance, immune system, and physical growth of infants and preschool- and school-age children. Iron deficiency anemia (IDA) increases children's susceptibility to some metals, including the highly toxic lead (Pb), but the character of this relationship is still disputed. Thus, this study aimed to review and meta-analyze the association between the IDA and blood lead levels (BLL) among children, based on papers indexed by international scientific databases and published up to September 2021. A search was performed of the literature in several databases including the ISI Web of Science, PubMed, and Scopus. The final papers were assessed concerning their quality based on the Newcastle-Ottawa Scale (NOS) for cross-sectional studies. Moreover, analyses were performed using R statistical software with the "meta" package. Of the 1528 articles found, only 12 studies met the inclusion criteria and were considered in the meta-analysis. Significantly higher BLL in IDA children (SMD = 2.40; CI 95%, 0.93-3.87 µg/L; p = 0.0014) was seen when compared to non-IDA children. Moreover, the pooled OR is equal to 2.75 (CI 95%, 1.10-6.85 µg/L; p = 0.0303) suggesting a higher risk of IDA development among children with BLL > 10 µg/dL. Thus, we recommend systematic monitoring of Fe and Pb levels among children, especially in countries with limited sources of nutritious food. Since only a few studies were available for this meta-analysis, further studies are necessary to examine the association between IDA and BLL in detail.

MOLECULAR MECHANISMS OF LEAD NEUROTOXICITY

Lead (Pb2+) is a non-essential metal with numerous industrial applications that have led to ts ubiquity in the environment. Thus, not only occupational-exposed individuals' health is compromised, but also that of the general population and in particular children. Notably, although the central nervous system is particularly susceptible to Pb2+, other systems are affected as well. The present study focuses on molecular mechanisms that underlie the effects that arise from the presence of Pb2+ in situ in the brain, and the possible toxic effects that follows. As the brain barriers represent the first target of systemic Pb2+, mechanisms of Pb2+ entry into the brain are discussed, followed by a detailed discussion on neurotoxic mechanisms, with special emphasis on theories of ion mimicry, mitochondrial dysfunction, redox imbalance, and neuroinflammation. Most importantly, the confluence and crosstalk between these events is combined into a cogent mechanism of toxicity, by intertwining recent and old evidences from humans, in vitro cell culture and experimental animals. Finally, pharmacological interventions, including chelators, antioxidants substances, anti-inflammatory drugs, or their combination are reviewed as integrated approaches to ameliorate Pb2+ harmful effects in both developing or adult organisms.

Role of lead in dental diseases

Lead (Pb) is ubiquitous in our environment and causes many pathophysiological health effects, including dental diseases. Dental Pb levels are considered good biological indicators of environmental and occupational Pb exposure. Pb in blood and saliva causes imbalances in the growth of oral microflora. The pH of saliva decreases, interferes with and interacts with bone-seeking elements, changes oral inflammatory parameters, generates reactive oxygen species, causes oxidative damage, and delays the mineralization process, leading to dental diseases. Pb's dental diseases include periodontitis, enamel lesions and defects, fluorosis, Burton's line, and tooth loss. Environmental and physiological factors, including age, gender, tooth type and position, pregnancy and lactation, eating and drinking habits, smoking habits, and exposures from Pb-contaminated residential and occupational areas, affect the distribution of Pb in blood, bone, and saliva, which contributes to dental diseases. However, living and working in Pb free areas can prevent environmental and occupational Pb exposure. Healthy lifestyles and eating habits, prohibiting smoking and alcohol drinking, further help prevent Pb exposure. Also, the fluoridation of water, salt, and milk provide nutritional supplements of trace elements, which can help prevent teeth from absorbing Pb from the environment, thereby reducing the risk of dental diseases.

Association of Musculoskeletal Disorders and Inflammation Markers in Workers Exposed to Lead (Pb) from Pb-battery Manufacturing plant

Background:

Lead (Pb) deposits in the skeletal system on chronic exposure and releases to circulation over a period. The musculoskeletal disorders (MSDs) are associated with enhanced expression of inflammation. The combination of Pb-exposure and MSDs induced inflammation was not attempted.

Objective:

This study was conducted to examine the association between MSDs and inflammatory markers in workers exposed to Pb from Pb-battery plant.

Material and Methods:

In a case-control study design, the study enrolled 176 male Pb-exposed workers as study subjects and 80 healthy workers with no occupational exposure to Pb as control subjects. The Nordic musculoskeletal questionnaire was used to assess the MSDs. From the blood sample, blood lead level (BLL) and High Sensitivity C-reactive protein (Hs-CRP) were estimated as markers of Pb-exposure and Inflammatory marker respectively. The BLL was estimated by flame atomic absorption spectrometric method and the Hs-CRP by using a diagnostic kit method.

Results:

Significantly high proportions of MSDs were noted in study subjects as compared to controls. The MSDs identified in the study subjects were at low back (33%) followed by knee (26%), shoulders (16%), neck (14%), ankle/foot (11%), wrist/hand (10%), elbows (8%), upper back (7%), and hips/thighs (5%). The significant association between Pb-exposure and MSDs among study subjects was mainly noted in low back and ankle/foot. Also, significantly high serum Hs-CRP levels were noted among study subjects with ankle/foot MSDs.

Conclusion:

Pb-exposure and inflammatory markers were significantly associated with lower limbs of MSDs.

Effect of Lead Exposure on the Status of Reticulocyte Count Indices among Workers from Lead Battery Manufacturing Plant

Earlier studies conducted on lead-exposed workers have determined the reticulocyte count (RC) (%), but the parameters of Absolute Reticulocyte Count (ARC), Reticulocyte Index (RI), and Reticulocyte Production Index (RPI) were not reported. This study assessed the effect of lead (Pb) exposure on the status of reticulocyte count indices in workers occupied in lead battery plants. The present cross-sectional study was carried out on 391 male lead battery workers. The blood lead levels (BLL) were determined by using an Atomic Absorption Spectrophotometer. The RC (%) was estimated by using the supravital staining method. The parameters, such as ARC, RI, and RPI, were calculated by using the RC (%) with the red cell indices (RBC count and hematocrit). The levels of RBC count and hematocrit were determined by using an ABX Micros ES-60 hematology analyzer. The levels of reticulocyte count indices - RC (%), ARC, RI, and RPI significantly increased with elevated BLL. The association between BLL and reticulocyte count indices was positive and significant. The results of linear multiple regression analysis showed that the reticulocyte count (β = 0.212, P < 0.001), ARC (β = 0.217, P < 0.001), RI (β = 0.194, P < 0.001), and RPI (β = 0.208, P < 0.001) were positively associated with BLL. The variable, smoking habits, showed a significant positive association with reticulocyte count indices: RC (%) (β = 0.188, P < 0.001), ARC (β = 0.174, P < 0.001), RI (β = 0.200, P < 0.001), and RPI (β = 0.151, P < 0.005). The study results revealed that lead exposure may cause reticulocytosis with an increase of reticulocyte count indices.