DNA damage and ALAD polymorphism in high blood lead (Pb) levels of pregnant women attending a tertiary care teaching hospital

Background

Pregnant women are particularly vulnerable to lead toxicity due to increased absorption and decreased elimination of lead from their bodies. The δ-aminolevulinic acid dehydratase (ALAD) gene plays a crucial role in lead metabolism, and its polymorphisms have been implicated in modifying the susceptibility to lead toxicity.

Methods

A cross-sectional study was conducted involving 90 pregnant women and blood samples were collected to measure blood lead levels (BLL) and assessed DNA damage using the comet assay. ALAD polymorphisms were genotyped using PCR-RFLP analysis with MspI restriction enzyme. Statistical analysis, including chi-square tests, logistic regression, and correlation analysis, was performed to determine associations between ALAD polymorphisms, BLL, and DNA damage.

Results

From 90 pregnant women the participants, 16 had high BLL (≥5 μg/dL), while the remaining 74 had normal levels (<5 μg/dL). The ALAD 1-2 genotype was found to be significantly associated with high BLL (p < 0.001). Pregnant women with the ALAD 1-2 genotype exhibited higher levels of DNA damage compared to those with other genotypes (p < 0.001). Furthermore, a positive correlation was observed between the transfer of lead concentration from mother to infant and DNA damage severity (r = 0.511, p < 0.001).

Conclusions

The combination of comet assay and polymorphism analysis offers a comprehensive approach to understanding the impact of lead exposure during pregnancy. These findings underscore the urgent need for effective regulatory measures to reduce lead exposure in the environment and mitigate its adverse effects of lead on maternal and child health.

Diagnostic Bioliquid Markers for Pancreatic Cancer: What We Have vs. What We Need

Pancreatic ductal adenocarcinoma (PDAC), the most common type of pancreatic cancer, currently has a dismal five-year survival rate of approximately 10% due to late diagnosis and a lack of efficient treatment options such as surgery. Furthermore, the majority of PDAC patients have surgically unresectable cancer, meaning cancer cells have either reached the surrounding blood vessels or metastasized to other organs distant from the pancreas area, resulting in low survival rates as compared to other types of cancers. In contrast, the five-year survival rate of surgically resectable PDAC patients is currently 44%. The late diagnosis of PDAC is a result of little or no symptoms in its early stage of development and a lack of specific biomarkers that may be utilized in routine examinations in the clinic. Although healthcare professionals understand the importance of early detection of PDAC, the research on the subject has lagged and no significant changes in the death toll of PDAC patients has been observed. This review is focused on understanding potential biomarkers that may increase the early diagnosis of PDAC patients at its surgically resectable stage. Here, we summarize the currently available biomarkers used in the clinic as well as those being developed with the hope of providing insight into the future of liquid biomarkers to be used in routine examinations for the early diagnosis of PDAC.

Modification by genetic polymorphism of lead-induced IQ alteration: a systematic review

As well as a lead-related environmental factor, genetic factors could also corroborate important changes in intelligence quotient (IQ) through single-nucleotide polymorphisms. Thus, a systematic review was carried out to evaluate the possible influence of polymorphism on blood Pb levels and IQ points in pediatric patients (0-19 years old). Following the PRISMA guideline, the studies were systematically collected on PubMed, Scopus, and Embase databases. Six genes (transferrin (TF); glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A); glutamate ionotropic receptor NMDA type subunit 2B (GRIN2B); dopamine receptor D2/ankyrin repeat and kinase domain containing 1 ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1); aminolevulinate dehydratase (ALAD); vitamin D receptor (VDR)) were found in six selected articles. In these genes, 11 single-nucleotide polymorphisms were searched and six different types of variations (missense variant, intron variant, synonymous variant, stop, stop gained) were observed. Due to the few studies in the literature, there is no conclusive data to point out that there is a direct relationship between polymorphisms, Pb levels, and reduction of IQ points.

Preventive Effect of Limosilactobacillus fermentum SCHY34 on Lead Acetate-Induced Neurological Damage in SD Rats

Lead poisoning caused by lead pollution seriously affects people's health. Lactic acid bacteria has been shown to be useful for biological scavenging of lead. In this experiment, Sprague-Dawley (SD) rats were treated with 200 mg/L of lead acetate solution daily to induce chronic lead poisoning, and oral Limosilactobacillus fermentum (L. fermentum) SCHY34 to study its mitigation effects and mechanisms on rat neurotoxicity. The L. fermentum SCHY34 showed competent results on in vitro survival rate and the lead ion adsorption rate. Animal experiments showed that L. fermentum SCHY34 maintained the morphology of rat liver, kidney, and hippocampi, reduced the accumulation of lead in the blood, liver, kidney, and brain tissue. Further, L. fermentum SCHY34 alleviated the lead-induced decline in spatial memory and response capacity of SD rats, and also regulated the secretion of neurotransmitters and related enzyme activities in the brain tissue of rats, such as glutamate (Glu), monoamine oxidase (MAO), acetylcholinesterase (AchE), cyclic adenosine monophosphate (cAMP), and adenylate cyclase (AC). In addition, the expression of genes related to cognitive capacity, antioxidation, and anti-apoptotic in rat brain tissues were increased L. fermentum SCHY34 treatment, such as brain-derived neurotrophic factor (BDNF), c-fos, c-jun, superoxide dismutase (SOD)1/2, Nuclear factor erythroid 2-related factor 2 (Nrf2), and B-cell lymphoma 2 (Bcl-2), and so on. L. fermentum SCHY34 showed a great biological scavenging and potential effect on alleviating the toxicity of lead ions.

Activated Carbon Fabric Mask Reduces Lead Absorption and Improves the Heme Biosynthesis and Hematological Parameters of Battery Manufacturing Workers

Activated carbon fabrics (ACF) mask prevents the absorption of lead and reduce its adverse effects of human health. Aim of this study to know the blood lead level and its effects on heme biosynthesis and hematological parameters after using 2 months activated carbon fabric mask of battery manufacturing workers (BMW). Blood lead level, heme biosynthesis and hematological parameters were measured by using standard method. Blood lead level (P < 0.001, - 13.5%) was significantly decreased, activated δ-aminolevulinic acid dehydratase (P < 0.001, 11.97%) and non-activated δ- aminolevulinic acid dehydratase (P < 0.001, 23.17%) enzyme activity were significantly increased, however, the ratio of activated to Non-activated δ- ALAD (P < 0.001, - 10.13%) was significantly decreased, urinary excretion of δ- aminolevulinic acid (P < 0.001, - 10.49%) and porphobilinogen (P < 0.001, - 7.38%) were significantly decreased after using 2 months ACF mask as compared to before using mask of BMW. Hematological parameters i.e Hb (P < 0.05, 13.42%), PCV (P < 0.05, 7.23%), MCV (P < 0.05, 1.9%) were significantly increased and total WBC count (P < 0.05, - 5.18%) was significantly decreased after using 2 months ACF mask as compared to before using mask of BMW. Two months using ACF mask reduces the blood lead level and improves the δ-ALDH activity and hematological parameters, decreases the urinary excretion of δ-ALA, PBG of battery manufacturing workers. Therefore, the regular using of ACF mask is beneficial to prevent the lead absorption and its adverse effects on human health.

Maternal Δ-aminolevulinic acid dehydratase 1-2 genotype enhances fetal lead exposure and increases the susceptibility to the development of cerebral palsy

Limited epidemiologic studies questioned the association between pre- and postnatal lead exposure and the development of cerebral palsy (CP). Moreover, the genotypes of δ-aminolevulinic acid dehydratase (δ-ALAD) in CP patients and their mothers and their association to the blood lead levels (BLLs) were not previously studied. This study aimed to evaluate the association between δ-ALAD gene polymorphism and BLL in cases of CP and their mothers. A case control study was carried out on 23 CP cases and equal number of healthy matched controls. The mothers of the included children were asked to answer a questionnaire involving the baseline clinical and demographic characteristics. Also, questionnaires were done to detect the sources of environmental lead exposure and screen lead exposure during the pregnancy period. BLL, δ-ALAD enzyme activity, and genetic analysis for ALAD G177C were done for each child and his mother. There was significant (p < 0.001) elevation of BLL in CP cases and their mothers that was positively correlated (r = 0.436, p < 0.05). There were progressive decreases in δ-ALAD activity with increasing BLL in both children and mothers (p < 0.05). There were non-significant (p > 0.05) differences between CP and the control group regarding frequency of ALAD G177C genotypes, while there was a significant (p = 0.04) increase in the frequency of ALAD 1-2 (GC) genotype in the mothers of the CP group associated with high BLL and significant decrease in δ-ALAD activity (p < 0.001). The study can indicate the significance of δ-ALAD gene polymorphism in the prenatal exposure to lead and the affection of the developing brain, pointing to the importance of controlling lead in pregnant women especially those with ALAD 1-2 genotype.

Influence of VDR and HFE polymorphisms on blood lead levels of occupationally exposed workers

Lead is a ubiquitous heavy metal toxin of significant public health concern. Every individual varies in their response to lead's toxic effects due to underlying genetic variations in lead metabolizing enzymes or proteins distributed in the population. Earlier studies, including our lab, have attributed the influence of ALAD (δ-Aminolevulinate dehydratase) polymorphism on blood lead retention and ALAD activity. The present study aimed to investigate the influence of VDR (Vitamin D receptor) and HFE (Hemochromatosis) polymorphisms in modulating blood lead levels (BLLs) of occupationally exposed workers. 164 lead-exposed subjects involved in lead alloy manufacturing and battery breaking and recycling processes and 160 unexposed controls with BLLs below 10 µg/dL recruited in the study. Blood lead levels, along with a battery of biochemical assays and genotyping, were performed. Regression analysis revealed a negative influence of BLLs on ALAD activity (p < 0.0001) and a positive influence on smokeless tobacco use (p < 0.001) in lead-exposed subjects. A predicted haplotype of the three VDR polymorphisms computed from genotyping data revealed that T-A-A haplotype increased the BLLs by 0.93 units (p ≤ 0.05) and C-C-A haplotype decreased the BLLs by 7.25 units (p ≤ 0.05). Further analysis revealed that the wild-type CC genotype of HFE H63D presented a higher median BLL, indicating that variant C allele may have a role in increasing the concentration of lead. Hence, the polymorphism of genes associated with lead metabolism might aid in predicting genetic predisposition to lead and its associated effects.

Relationship between blood Lead status and anemia in Ugandan children with malaria infection

BACKGROUND

In Uganda, childhood anemia remains a health challenge and is associated with malaria infection as well as iron deficiency. Iron deficiency is intertwined with nutritional status, age and other comorbidities including helminths and Lead toxicity. Environmental Lead levels accounts for one's blood Lead (BL) levels. Blood Lead competitively blocks iron absorption, inhibits hemoglobin (Hb) biosynthesis and elevates free erythrocyte protoporphyrin (FEP) levels. Lead toxicity's contribution towards anemia pathogenesis, especially during malaria infection has not been studied. Concomitant exposure to both malaria infection and Lead pollution, exacerbates the anemia status. This study therefore aimed at expounding the anemia status of these Ugandan children aged under 5years who are exposed to both malaria infection and environmental Lead pollution.

METHODS

Briefly, venous blood samples from 198 children were microscopically assayed for malaria parasite density (PD), and hemoglobin (Hb) concentrations using the cyanmethemoglobin method, while BL and FEP levels were determined by the standard atomic absorption spectrophotometric and fluorometric methods respectively.

RESULTS

One hundred and fifty-one (76.3%) of the children analyzed had moderate anemia (Hb <10>5 g/dL) with Means of BLL=8.6 µg/dL, Hb =7.5 g/dL, FEP/Hb =8.3 µg/g and PD =3.21×10³ parasites / µL, while eight (4%) were severely anemic (<5 g/dL). Regression analysis and statistical correlation between PD and Hb (r = -0.231, R²= 0.15 P-value < 0.001) was negative and weak as compared to that between FEP/Hb and Hb (r = -0.6, R²=0.572 P-value=0.001).

CONCLUSION

Based on the study's findings, we conclude that BL significantly contributes to the pathogenesis of anemia and therefore its co-existence with malaria infection in the host exacerbates the anemia status.

Impact of chronic lead exposure on liver and kidney function and haematologic parameters

BACKGROUND

Lead, one of the most widely used metals because of its beneficial physical properties, has been reported to adversely influence several different organs and organ systems. The aim of the present study was to examine the effect of lead exposure on liver and renal function and haematologic parameters.

METHODS

This was a case-cohort study comparing adults with occupational, environmental or opium-related lead exposure with blood lead levels [BLL] >10 μg/dL (High blood lead level (HBLL) group and age- and gender-matched normal healthy individuals (Low blood lead level [LBLL] group with BLL <10 μg/dL). The complete blood count and concentrations of serum creatinine, urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT) were recorded for subsequent investigation.

RESULTS

The mean BLL was significantly higher in the HBLL than in the LBLL groups (51.36 ± 44.72 vs 4.17 ± 1.97 µg/dL). The Spearman's rho revealed a significant association between BLL and urea (r = 0.25, P < 0.001), creatinine (r = 0.16, P = 0.02), AST (r = 0.42, P < 0.001) and ALT (r = 0.27, P < 0.001). The median [IQR] serum urea (34 mg/dL [27-221]) vs (30 [27-36]), creatinine (0.9 mg/dL [0.8-1]) vs (0.8 [0.7-0.9]), ALT (25 mg/dL [16-49]) vs (22 [16-30]) and AST concentrations (29 mg/dL [20-42]) vs (20 [18-24]) were all significantly higher (P < 0.05) in the HBLL group compared to the LBLL group. The median [IQR] haemoglobin (12.6 g/dL [10.4-15.4]) vs (15.2 [14.6-16.3] and haematocrit (36.9% [31-44.8]) vs (45.6 [43.6-48.2]) were both significantly lower (P < 0.001) in the HBLL group than in the LBLL group.

CONCLUSION

The results indicated that people with chronic lead exposure with BLLs greater than 10 μg/dL are at risk of renal, liver and haematologic impairments.

Oxidative stress in opium users after using lead-adulterated opium: The role of genetic polymorphism

Use of lead-adulterated opium has become one of the major sources of lead poisoning in Iran. This study was designed to assess clinical effects and oxidative stress and its association with GSTM1, GSTT1, NQO1, and ALAD genes polymorphisms and blood lead level (BLL) in lead-adulterated opium users. The oxidative stress status in 192 opium users with lead poisoning symptoms measured and compared with 102 healthy individuals. Gluthatione S-transferase (GST)-M1 and -T1 genes deletion, NQO1 rs1800566, and δ-aminolevulinic acid dehydratase (ALAD) rs1800435 polymorphisms were determined using PCR and PCR-RFLP. The relation between the polymorphisms, BLL, and oxidative stress parameters were analysed using multivariate linear regressions. The common symptoms of lead toxicity were gastrointestinal and neurologic complications. Oxidative stress was significantly higher in opium addicts and lipid peroxidation significantly correlated with BLL. There was significant association between ALAD rs1800435 and BLL, and the BLL was significantly lower in the patients with ALAD 1-2 genotype. Use of lead-adulterated opium causes high frequency of lead toxicity symptoms, hematological and biochemical abnormalities, and oxidative stress which are associated with BLL. Route of opioid use and the polymorphism of rs1800435 in ALAD gene are the major determinants of BLL in lead-adulterated opium users.

Effect of Vitamin C Supplementation on Blood Lead Level, Oxidative Stress and Antioxidant Status of Battery Manufacturing Workers of Western Maharashtra, India

INTRODUCTION

The high blood lead level induces oxidative stress and alters the antioxidant status of battery manufacturing workers. Supplementation of vitamin C is beneficial to reduce the oxidative stress and to improve the antioxidant status of these workers.

AIM

The main aim of this study was to observe the changes in blood lead levels, oxidative stress i.e. serum lipid peroxide and antioxidant status parameters such as erythrocyte superoxide dismutase and catalase and serum nitrite after the vitamin C supplementation in battery manufacturing workers.

MATERIALS AND METHODS

This study included 36 battery manufacturing workers from Western Maharashtra, India, having age between 20-60 years. All study group subjects were provided vitamin C tablets (500 mg/day for one month) and a blood sample of 10 ml each was drawn by puncturing the anterior cubital vein before and after vitamin C supplementation. The biochemical parameters were estimated by using the standard methods.

RESULTS

Blood lead levels were not significantly altered, however, serum lipid peroxide (p<0.001, -15.56%) and serum nitrite (p<0.001, -21.37%) levels showed significant decrease and antioxidant status parameters such as erythrocyte superoxide dismutase (p<0.001, 38.02%) and catalase (p<0.001, 32.36%) revealed significant increase in battery manufacturing workers after the supplementation of vitamin C.

CONCLUSION

One month vitamin C supplementation in battery manufacturing workers is not beneficial to decrease the blood lead levels. However, it is helpful to reduce the lipid peroxidation and nitrite formation and enhances the erythrocytes superoxide dismutase and catalase activity.

Association between delta-aminolevulinic acid dehydratase polymorphism and placental lead levels

Lead inhibits the delta-aminolevulinic acid dehydratase (ALAD) activity and results in neurotoxic aminolevulinic acid accumulation in the blood. During pregnancy, lead in the maternal blood can easily cross the placenta. The aim of this study was to determine whether the maternal ALAD G177C polymorphism (rs1800435) was related to the placental lead levels. The study population comprised 97 blood samples taken from mothers to investigate ALAD G177C polymorphism and their placentas to measure lead levels. ALAD G177C polymorphism was detected by standard polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique and atomic absorption spectrometry (AAS) equipped with a graphite furnace and Zeeman background correction system was used for lead determination. The median placental lead levels for ALAD1-1, ALAD1-2 and ALAD2-2 genotypes were 7.54 μg/kg, 11.78 μg/kg and 18.53 μg/kg, respectively. Statistically significant association was found between the maternal ALAD G177C polymorphism and placental lead levels (p<0.05). This study suggested that maternal ALAD G177C polymorphism was associated with placental lead levels.

Neurological and Epigenetic Implications of Nutritional Deficiencies on Psychopathology: Conceptualization and Review of Evidence

In recent years, a role for epigenetic modifications in the pathophysiology of disease has received significant attention. Many studies are now beginning to explore the gene-environment interactions, which may mediate early-life exposure to risk factors, such as nutritional deficiencies and later development of behavioral problems in children and adults. In this paper, we review the current literature on the role of epigenetics in the development of psychopathology, with a specific focus on the potential for epigenetic modifications to link nutrition and brain development. We propose a conceptual framework whereby epigenetic modifications (e.g., DNA methylation) mediate the link between micro- and macro-nutrient deficiency early in life and brain dysfunction (e.g., structural aberration, neurotransmitter perturbation), which has been linked to development of behavior problems later on in life.

Association between δ-aminolevulinate dehydratase G177C polymorphism and blood lead levels in brain tumor patients

As the δ-aminolevulinic acid dehydratase (ALAD) G177C polymorphism affects the toxicokinetics of lead in the body, and the corresponding exposure to lead may increase the risk of adult brain tumors, we hypothesize that there is a possible association of the ALAD G177C genotype and the risk of brain tumors in human. Therefore, the aim of the present study was to clarify the role of the ALAD enzyme gene polymorphism at position G177C in the pathogenesis of brain tumors and its correlation to lead exposure. The ALAD gene polymorphism at position G177C was genotyped using the polymerase chain reaction with restriction fragment length polymorphism method and measured the blood lead level by atomic absorption in 81 brain tumor patients and compared the results with 81 controls. The frequency of the GC genotype (ALAD1-2) was significantly increased in primary brain tumor patients compared to the control group. The genotype frequency of ALAD2 (ALAD1-2 and ALAD2-2) was significantly higher in the meningioma patients but was not significant in glioma patients. There was no significant difference in the number of patients and blood lead level when compared with the control. There was a significant increase when compared to ALAD1 regarding a mean value of the lead level. The genotyping of the ALAD G177C polymorphism in the present study revealed a significant association between ALAD2 and brain tumors. The ALAD G177C polymorphism may modify the lead kinetics in the blood, is associated with higher blood lead burden and may provide a biomarker of neurotoxic risk.

The relationship between selected VDR, HFE and ALAD gene polymorphisms and several basic toxicological parameters among persons occupationally exposed to lead

The aim of this study was to find a relationship between polymorphisms of ALAD rs1805313, rs222808, rs1139488, VDR FokI and HFE C282Y and H63D and basic toxicological parameters (lead and ZnPP blood concentration) in people occupationally exposed to lead. We collected data of 101 workers (age 25-63 years) directly exposed to lead. The toxicological lab tests included blood lead, cadmium and ZnPP concentration measurement and arsenic urine concentration measurement. Workers were genotyped for ALAD (rs1805313, rs222808, rs1139488), HFE (C282Y, H63D) and VDR (FokI). Individuals with the lead exposure and coexisting F allel in the locus Fok-I of VDR gene are suspected of higher zinc protoporphyrins concentrations. Workers exposed to the lead with the Y allel in the locus C282Y of the HFE gene are predisposed to lower ZnPP levels and individuals with coexisting H allel in the locus H63D HFE gene are predisposed to lower Pb-B levels. The T allel in the locus rs1805313 of the ALAD gene determines lower Pb-B and ZnPP levels in lead-exposed individuals. The heterozigosity of the locus rs2228083 of the ALAD gene has a strong predilection to higher Pb-B levels. The carriage of the C allel in the locus rs1139488 of the ALAD gene might determine higher Pb-B levels and the heterozigosity of the locus rs1139488 of the ALAD gene might result in higher ZnPP levels.

CONCLUSION

The study revealed relationship between VDR, HFE and ALAD genes polymorphism and basic toxicological parameters in occupationally exposed workers.

Effects of lead exposure on the status of platelet indices in workers involved in a lead-acid battery manufacturing plant

This study was carried out to determine the effect of Pb exposure on the status of platelet indices in workers exposed to Pb during lead-acid battery plant process. Platelet indices and blood lead levels (BLLs) were determined in 429 male workers. BLLs were determined by using an atomic absorption spectrophotometer. Platelet indices in the samples were quantified by using the Sysmex KX-21 hematology analyzer. The levels of platelet count (PLT), plateletcrit (PCT) and mean platelet mass (MPM) were significantly decreased and platelet distribution width (PDW), platelet large cell ratio (P-LCR) and mean platelet volume were increased with an increase in BLLs. The results of linear multiple regression analysis showed that the platelet count (β -0.143, P=0.005), PCT (β -0.115, P=0.023) and MPM (β -0.110, P=0.030) were negatively associated with BLLs and P-LCR (β 0.122, P=0.016) was positively associated with BLLs. The variable of body mass index showed a positive association with PCT (β 0.105, P=0.032) and MPM (β 0.101, P=0.039). The results of the study may indicate that lead exposure may impair coagulation function through endothelial tissue injury and reduction of nitric oxide.

Lead exposure: a summary of global studies and the need for new studies from Saudi Arabia

Lead poisoning (plumbism) can cause irreversible genetic and reproductive toxicity, hematological effects, neurological damage, and cardiovascular effects. Despite many efforts to minimize lead poisoning, it continues to be a major health concern in many developing and developed countries. Despite efforts to control lead exposure and toxicity, serious cases of lead poisoning increasingly occur as a result of higher vehicular traffic and industrialization. The biomarkers for identification of genetic susceptibility to a particular disease are useful to identify individuals who are at risk for lead poisoning. Although many such studies have been taken up elsewhere, very few studies were performed in Saudi Arabia to assess susceptibility to lead poisoning. This indicates an urgent need for testing of susceptible individuals. The present paper was planned to understand the genetic susceptibility to lead toxicity in the various population studies conducted worldwide and also to correlate it with the current scenario in Saudi Arabia. Such studies are necessary for appropriate precautions in terms of diet and avoiding exposure to be used in order to prevent adverse health effects.

Lead Nephropathy: Revisiting an Overlooked Cause of Kidney Disease

Despite the recognition of lead nephropathy as a consequence of environmental and occupational lead exposure, lead nephropathy still appears to be underrecognized by physicians as a cause and promoter of chronic kidney disease (CKD), especially in people with more apparent causative factors such as diabetes and hypertension. This review focuses on the clinical, pathophysiological and epidemiological perspectives of lead nephropathy with the objective of promoting the awareness of this important but overlooked cause of CKD among physicians. Literature was reviewed using available medical journals and online literature search through Google, Pubmed, Medline, Medscape and HINARI databases. The key words employed were: Lead Nephropathy, Environmental and Occupational lead exposure and chronic kidney disease. Lead nephropathy which is a tubulointerstitial nephritis, may present acutely or chronically in association with hypertension. The clinical diagnosis of lead nephropathy is complex, because the symptoms are varied and non-specific especially with subclinical nephrotoxicity. The recognition of lead nephropathy can be enhanced if physicians have a high index of suspicion in the assessment of patients with renal disease. It is recommended that the evaluation of environmental and occupational nephrotoxins like lead be incorporated into programs for the prevention of CKD, especially in developing countries where lead exposure and toxicity still remain largely unchecked and the prevalence and burden of CKD is increasing.

Environmental exposure to lead (Pb) and variations in its susceptibility

Based on exposure frequency and intrinsic toxicity, lead (Pb) ranks one of the highest priority toxic materials. Continuous regulation of environmental Pb exposure has contributed to dramatically diminished exposure levels of Pb, for example, blood level of Pb. However, the safety level of Pb is not established, as low-level exposure to Pb still shows severe toxicity in high susceptible population and late onset of some diseases from early exposure. In the present study, we focused on food-borne Pb exposure and found broad variations in Pb exposure levels via food among countries. In addition, there are genetic or ethnical variations in Pb-targeted and protective genes. Moreover, various epigenetic alterations were induced by Pb poisoning. Therefore, we suggest a systemic approach including governmental (public) and individual prevention from Pb exposure with continuous biological monitoring and genetic or epigenetic consideration.

A probable role of blood lead levels on some haematological parameters in traffic police, Lahore, Pakistan

The impact of elevated blood lead level on some haematological parameters was studied in the field force of Lahore traffic police, in Pakistan. The blood samples were tested for total leucocytes count (TLC) and differential leucocytes count in the persons with high and low blood lead levels. The TLC and percentage of neutrophils and eosinophils were observed as being significantly elevated in the policemen. No significant change was observed in the percentage of lymphocytes, while the percentage of monocytes was observed as being significantly less in the field force of traffic police.

Effects of delta-aminolevulinic acid dehydratase polymorphisms on susceptibility to lead in Han subjects from southwestern China

This study is to determine the distribution of the delta-aminolevulinic acid dehydratase (ALAD) polymorphism among Han subjects of the Chinese population and to study whether the polymorphism in the ALAD gene modifies the toxicity of lead in lead-exposed workers. For this purpose we conducted a cross-sectional study on 156 Chinese workers who were exposed to lead in lead-acid battery and electric-flex manufacturing plants. The authors found that the allele frequencies of ALAD1 and ALAD2 were 0.9679 and 0.0321, respectively. Workers with the ALAD 1-1 genotype were associated with higher blood lead levels than those with the ALAD 1-2 genotype. Blood and urine lead levels were much higher in storage battery workers than in cable workers. The self-conscious symptom survey showed that the incidences of debilitation, amnesia and dreaminess were much higher in those had more than five years of tenure or contact with lead on the job within the ALAD 1-1 genotype subgroup. Laboratory examinations showed that serum iron and zinc levels in workers' with the ALAD 1-2 genotype were higher than those with the ALAD 1-1 genotype, especially in storage-battery workers. Correlation analysis indicated that the blood lead level negatively correlated with serum calcium, iron and zinc level. The data of this study suggest that the ALAD gene polymorphism and serum ion levels may modify the kinetics of lead in blood. Therefore, the authors recommend that an adequate intake of dietary calcium, iron, and zinc or the calcium, iron, and zinc supplementation should be prescribed to Chinese lead exposed workers.

Assessment of immunotoxicity parameters in individuals occupationally exposed to lead

Although adverse health effects produced by lead (Pb) have long been recognized, studies regarding the immunotoxic effects of occupational exposure report conflicting results. In a previous study, alterations in some immunological parameters were noted in 70 Pb-exposed workers. In view of these results, it was of interest to extend this study comprising a larger population and increasing the number of immunological endpoints assessed. Accordingly, in this study the immunotoxic effects of occupational exposure to Pb were assessed by analyzing (1) percentages of lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, and CD56⁺/16⁺); (2) concentration of plasma cytokines, namely, interleukin (IL) 2, IL4, IL6, IL10, tumor necrosis factor (TNF) α, and interferon (IFN) γ; and (3) plasma concentrations of neopterin, tryptophan (Trp), and kynurenine (Kyn). In addition, the possible influence of genetic polymorphisms in the vitamin D receptor (VDR) and δ-aminolevulinic acid dehydratase (ALAD) genes on immunotoxicity parameters was studied. Exposed workers showed significant decreases in %CD3⁺, %CD4⁺/%CD8⁺ ratio, IL4, TNFα, IFNγ, and Kyn to Trp ratio (Kyn/Trp), and significant increases in %CD8⁺, IL10, and Trp levels. All these parameters, except Trp, were significantly correlated with exposure biomarkers. No significant influence of genetic polymorphisms was observed. Significant correlation between Kyn/Trp and neopterin concentrations suggests an involvement of indoleamine 2,3-dioxygenase in the Trp metabolic alterations, which may contribute to some of the immune alterations observed. Results obtained suggest that occupational exposure to PB may influence the immune system by impairing several mechanisms, which might ultimately produce deregulation of the immune response and diminish immunosurveillance in exposed individuals.

Exploring potential sources of differential vulnerability and susceptibility in risk from environmental hazards to expand the scope of risk assessment

Genetic factors, other exposures, individual disease states and allostatic load, psychosocial stress, and socioeconomic position all have the potential to modify the response to environmental exposures. Moreover, many of these modifiers covary with the exposure, leading to much higher risks in some subgroups. These are not theoretical concerns; rather, all these patterns have already been demonstrated in studies of the effects of lead and air pollution. However, recent regulatory impact assessments for these exposures have generally not incorporated these findings. Therefore, differential risk and vulnerability is a critically important but neglected area within risk assessment, and should be incorporated in the future.

A current global view of environmental and occupational cancers

This review is focused on current information of avoidable environmental pollution and occupational exposure as causes of cancer. Approximately 2% to 8% of all cancers are thought to be due to occupation. In addition, occupational and environmental cancers have their own characteristics, e.g., specific chemicals and cancers, multiple factors, multiple causation and interaction, or latency period. Concerning carcinogens, asbestos/silica/wood dust, soot/polycyclic aromatic hydrocarbons [benzo(a) pyrene], heavy metals (arsenic, chromium, nickel), aromatic amines (4-aminobiphenyl, benzidine), organic solvents (benzene or vinyl chloride), radiation/radon, or indoor pollutants (formaldehyde, tobacco smoking) are mentioned with their specific cancers, e.g., lung, skin, and bladder cancers, mesothelioma or leukemia, and exposure routes, rubber or pigment manufacturing, textile, painting, insulation, mining, and so on. In addition, nanoparticles, electromagnetic waves, and climate changes are suspected as future carcinogenic sources. Moreover, the aspects of environmental and occupational cancers are quite different between developing and developed countries. The recent follow-up of occupational cancers in Nordic countries shows a good example for developed countries. On the other hand, newly industrializing countries face an increased burden of occupational and environmental cancers. Developing countries are particularly suffering from preventable cancers in mining, agriculture, or industries without proper implication of safety regulations. Therefore, industrialized countries are expected to educate and provide support for developing countries. In addition, citizens can encounter new environmental and occupational carcinogen nominators such as nanomaterials, electromagnetic wave, and climate exchanges. As their carcinogenicity or involvement in carcinogenesis is not clearly unknown, proper consideration for them should be taken into account. For these purposes, new technologies with a balance of environment and gene are required. Currently, various approaches with advanced technologies--genomics, exposomics, etc.--have accelerated development of new biomarkers for biological monitoring of occupational and environmental carcinogens. These advanced approaches are promising to improve quality of life and to prevent occupational and environmental cancers.

Phylogenetic analysis of ALAD and MGP genes related to lead toxicity

Experimental studies in our laboratory have established the role of delta-aminolevulinic acid dehydratase (ALAD) and matrix gamma-carboxyglutamic acid (MGP) gene polymorphisms in the etiology of lead toxicity. Polymorphisms in these genes influenced the levels of lead in subjects exposed to this metal. In extension to our studies, we aimed to investigate the possible role of these proteins in evolution by studying the phylogenetic relationship and divergence of ALAD and MGP genes using computational phylogenetic methods. The human ALAD and MGP protein sequences from various species were retrieved from Swiss-Prot database and were compared using Basic Local Alignment Search Tool. Multiple sequence alignment was carried out using ClustalW with defaults, and phylogenetic trees for both the genes were built using neighbor-joining method as in Mega software. Our study indicated that ALAD is a highly conserved protein with the same metal binding site distributed in all the phyla (from archaea to chordates). Phylogenetic analysis of MGP gene revealed that it had an important role in the evolution of endogenous skeleton in contrast to exoskeleton of insects. Occurrence of these genes in evolution with conserved metal binding sites strengthens the role of ALAD and MGP genes in regulating heme biosynthesis and mineralization, respectively, in evolution and helps in better understanding of lead poisoning.

Association between a polymorphism of aminolevulinate dehydrogenase (ALAD) gene and blood lead levels in Japanese subjects

This cross-sectional study investigated the relationship between the aminolevulinate dehydrogenase (ALAD) genotype and blood lead levels among 101 Japanese workers. Blood lead concentration measurement, biomarkers, and genotyping were performed. The minor allele frequency (MAF) for ALAD (ALAD2) was 0.08. Although the blood lead level in the subjects with heterozygous GC genotype was significantly higher than those with homozygous GG genotype, there were no significant differences for hemoglobin, hematocrit, serum and urinary ALA levels among genotypes. ALAD2 genotype was significantly associated with the blood lead concentration, even in the environmental lead exposed subjects. Further confirmation with a large sample size is needed.