Blood levels of cadmium and lead in relation to breast cancer risk in three prospective cohorts

Blood Lead Level as Marker of Increased Risk of Ovarian Cancer in BRCA1 Carriers

BRCA1 mutations substantially elevate the risks of breast and ovarian cancer. Various modifiers, including environmental factors, can influence cancer risk. Lead, a known carcinogen, has been associated with various cancers, but its impact on BRCA1 carriers remains unexplored. A cohort of 989 BRCA1 mutation carriers underwent genetic testing at the Pomeranian Medical University, Poland. Blood lead levels were measured using inductively coupled plasma mass spectrometry. Each subject was assigned to a category based on their tertile of blood lead. Cox regression analysis was used to assess cancer risk associations. Elevated blood lead levels (>13.6 μg/L) were associated with an increased risk of ovarian cancer (univariable: HR = 3.33; 95% CI: 1.23-9.00; p = 0.02; multivariable: HR = 2.10; 95% CI: 0.73-6.01; p = 0.17). No significant correlation was found with breast cancer risk. High blood lead levels are associated with increased risk of ovarian cancer in BRCA1 carriers, suggesting priority for preventive salpingo-oophorectomy. Potential risk reduction strategies include detoxification. Validation in diverse populations and exploration of detoxification methods for lowering lead levels are required.

Mechanisms of Heavy Metal Cadmium (Cd)-Induced Malignancy

The environmental pollution of cadmium is worsening, and its significant carcinogenic effects on humans have been confirmed. Cadmium can induce cancer through various signaling pathways, including the ERK/JNK/p38MAPK, PI3K/AKT/mTOR, NF-κB, and Wnt. It can also cause cancer by directly damaging DNA and inhibiting DNA repair systems, or through epigenetic mechanisms such as abnormal DNA methylation, LncRNA, and microRNA. However, the detailed mechanisms of Cd-induced cancer are still not fully understood and require further investigation.

Blood Cadmium Level Is a Marker of Cancer Risk in Men

Cadmium (Cd) is a known carcinogen, but its impact on cancer risk at lower concentrations is poorly understood. Previous studies on Cd and cancer risk in men show inconsistent results, prompting further investigation. A prospective cohort study involving 2956 men was conducted. Blood Cd levels were measured, and participants were followed for 78 months to assess cancer incidence. Men with high blood Cd levels (>0.71 µg/L) had a significantly increased risk of cancer compared to those with low levels (<0.19 µg/L) (HR 3.42, p < 0.001), particularly among non-smokers (HR 3.74, p = 0.003), individuals aged < 60 years (HR 2.79, p = 0.017), and ≥60 (HR 4.63, p = 0.004). The influence of smoking on cancer risk based on Cd levels was not significant in this study. Blood Cd levels may influence cancer risk in men, emphasizing the importance of minimizing Cd exposure to reduce risk. Confirmation of these results in other populations is essential for effective preventive measures against Cd-related cancers.

Breast cancer risk for the joint exposure to metals and metalloids in women: Results from the EPIC-Spain cohort

Environmental factors play a role in breast cancer development. While metals and metalloids (MMs) include some carcinogens, their association with breast cancer depends on the element studied. Most studies focus on individual MMs, but the combined effects of metal mixtures remain unclear. The aim of this study was to analyze the relationship between the joint exposure to MMs and the risk of developing female breast cancer. We conducted a case-control study within the multicenter prospective EPIC-Spain cohort. Study population comprised 292 incident cases and 286 controls. Plasma concentrations of 16 MMs were quantified at recruitment. Potential confounders were collected using a questionnaire and anthropometric measurements. Mixed-effects logistic regression models were built to explore the effect of individual MMs. Quantile-based g computation models were applied to identify the main mixture components and to estimate the joint effect of the metal mixture. The geometric means were highest for Cu (845.6 ng/ml) and Zn (604.8 ng/ml). Cases had significantly higher Cu concentrations (p = 0.010) and significantly lower Zn concentrations (p < 0.001). Cu (+0.42) and Mn (+0.13) showed the highest positive weights, whereas Zn (-0.61) and W (-0.16) showed the highest negative weights. The joint effect of the metal mixture was estimated at an OR = 4.51 (95%CI = 2.32-8.79), suggesting a dose-response relationship. No evidence of non-linearity or non-additivity was found. An unfavorable exposure profile, primarily characterized by high Cu and low Zn levels, could lead to a significant increase in the risk of developing female breast cancer. Further studies are warranted to confirm these findings.

Differential effect of the duration of exposure on the carcinogenicity of cadmium in MCF10A mammary epithelial cells

The carcinogenic role of cadmium (Cd2+) in breast cancer is still debatable. Current data points to duration of exposure as the most important element. In our study, we designed an in vitro model to investigate the effects of 3 weeks versus 6 weeks of low-level CdCl2 exposure on MCF10A cells. Our results demonstrated that after 3 weeks of CdCl2 exposure the cells displayed significant changes in the DNA integrity, but there was no development of malignant features. Interestingly, after 6 weeks of exposure, the cells significantly increased their invasion, migration and colony formation capacities. Additionally, MCF10A cells exposed for 6 weeks to CdCl2 had many dysregulated genes (4905 up-regulated and 4262 down-regulated). As follows, Cd-induced phenotypical changes are accompanied by a profound modification of the transcriptomic landscape. Furthermore, the molecular alterations driving carcinogenesis in MCF10A cells exposed to CdCl2 were found to be influenced by the duration of exposure, as in the case of MEG8. This long non-coding RNA was down-regulated at 3 weeks, but up-regulated at 6 weeks of exposure. In conclusion, even very low levels of Cd (0.5 μM) can have significant carcinogenic effects on breast cells in the case of subchronic exposure.

Human exposure to heavy metals and related cancer development: a bibliometric analysis

As notifications on carcinogenicity of heavy metals increase, more and more attention is paid recently to heavy metals exposure. In our study, the human exposure to heavy metals and cancer knowledge epistemology was investigated using bibliometric analysis. The bibliometric data of the research articles were retrieved using following keywords: "heavy metal," "trace element", "cancer", "carcinogen", and "tumor" in the Scopus database. Specifically, 2118 articles published between 1972 and 2023 were found, covering a total of 1473 authors, 252 sources, and 2797 keywords. Retrospective data obtained from 251 documents and 145 journals were further analyzed by performance analysis and techniques of science mapping. The number of studies conducted in this field increased from one article published in 1972 to 18 articles published in 2022 in the study of Michael P Waalkes. The most impactful author regarding the number of published papers was Masoudreza Sohrabi with 7 publications. In the majority of the published papers, the most popular keywords were "cadmium" and "carcinogenicity". However, in recent 4 years, the emphasis has been placed more on epidemiology studies. Our study provides general knowledge about the trend of publication on the role of heavy metals in causing cancer. The leading researchers in the field of the effects of heavy metals on the development of cancer were identified in our studies. Our results might also create a better understanding of new and emerging issues and can be used as a comprehensive road map for future researchers.

Environmental cadmium exposure facilitates mammary tumorigenesis via reprogramming gut microbiota-mediated glutamine metabolism in MMTV-Erbb2 mice

Cadmium (Cd) is a heavy metal that has been widely reported to be linked to the onset and progression of breast cancer (BC). However, the mechanism of Cd-induced mammary tumorigenesis remains elusive. In our study, a transgenic mouse model that spontaneously develops tumors through overexpression of wild-type Erbb2 (MMTV-Erbb2) was constructed to investigate the effects of Cd exposure on BC tumorigenesis. The results showed that oral exposure to 3.6 mg/L Cd for 23 weeks dramatically accelerated tumor appearance and growth, increased Ki67 density and enhanced focal necrosis and neovascularization in the tumor tissue of MMTV-Erbb2 mice. Notably, Cd exposure enhanced glutamine (Gln) metabolism in tumor tissue, and 6-diazo-5-oxo-l-norleucine (DON), a Gln metabolism antagonist, inhibited Cd-induced breast carcinogenesis. Then our metagenomic sequencing and mass spectrometry-based metabolomics confirmed that Cd exposure disturbed gut microbiota homeostasis, especially Helicobacter and Campylobacter abundance remodeling, which altered the gut metabolic homeostasis of Gln. Moreover, intratumoral Gln metabolism profoundly increased under Cd-elevated gut permeability. Importantly, depletion of microbiota with an antibiotic cocktail (AbX) treatment led to a significant delay in the appearance of palpable tumors, inhibition of tumor growth, decrease in tumor weight, reduction in Ki67 expression and low-grade pathology in Cd-exposed MMTV-Erbb2 mice. Also, transplantation of Cd-modulated microbiota decreased tumor latency, accelerated tumor growth, increased tumor weight, upregulated Ki67 expression and exacerbated neovascularization as well as focal necrosis in MMTV-Erbb2 mice. In summary, Cd exposure induced gut microbiota dysbiosis, elevated gut permeability and increased intratumoral Gln metabolism, leading to the promotion of mammary tumorigenesis. This study provides novel insights into environmental Cd exposure-mediated carcinogenesis.

Research Recommendations for Selected IARC-Classified Agents: Impact and Lessons Learned

BACKGROUND

The International Agency for Research on Cancer (IARC) Monographs program assembles expert working groups who publish a critical review and evaluation of data on agents of interest. These comprehensive reviews provide a unique opportunity to identify research needs to address classification uncertainties. A multidisciplinary expert review and workshop held in 2009 identified research gaps and needs for 20 priority occupational chemicals, metals, dusts, and physical agents, with the goal of stimulating advances in epidemiological studies of cancer and carcinogen mechanisms. Overarching issues were also described.

OBJECTIVES

In this commentary we review the current status of the evidence for the 20 priority agents identified in 2009. We examine whether identified Research Recommendations for each agent were addressed and their potential impact on resolving classification uncertainties.

METHODS

We reviewed the IARC classifications of each of the 20 priority agents and identified major new epidemiological and human mechanistic studies published since the last evaluation. Information sources were either the published Monograph for agents that have been reevaluated or, for agents not yet reevaluated, Advisory Group reports and literature searches. Findings are described in view of recent methodological developments in Monographs evidence evaluation processes.

DISCUSSION

The majority of the 20 priority agents were reevaluated by IARC since 2009. The overall carcinogen classifications of 9 agents advanced, and new cancer sites with either "sufficient" or "limited" evidence of carcinogenicity were also identified for 9 agents. Examination of published findings revealed whether evidence gaps and Research Recommendations have been addressed and highlighted remaining uncertainties. During the past decade, new research addressed a range of the 2009 recommendations and supported updated classifications for priority agents. This supports future efforts to systematically apply findings of Monograph reviews to identify research gaps and priorities relevant to evaluation criteria established in the updated IARC Monograph Preamble. https://doi.org/10.1289/EHP12547.

Assessment of Cadmium (Cd) and Lead (Pb) Blood Concentration on the Risk of Endometrial Cancer

BACKGROUND

Cadmium (Cd) and lead (Pb) are heavy metals with carcinogenic potential. Their increased concentration has been correlated with a risk of malignancies, including breast, lung, kidney, gastrointestinal, and gynecological cancers. Most of the studies have evaluated tissue heavy metal concentration. To the best of our knowledge, this is the first study to evaluate blood Cd and lead levels in different uterine pathologies and the risk of endometrial cancer.

METHODS

This study included 110 patients with a histopathological diagnosis of endometrial cancer, endometrial polyps, endometrial hyperplasia, uterine myoma, and normal endometrium. The patients included in the study were assessed in terms of their endometrial cancer risk factors and blood heavy metal levels. The analysis was conducted using inductively coupled plasma optical emission spectrometry.

RESULTS

There was a significant difference in the Cd and Cd/Pb ratio among the different groups of patients (p = 0.002), with higher a median Cd concentration among the endometrial cancer patients. The differences in Pb concentration were not significant (p = 0.717). There were also no differences in the Cd and Pb concentrations based on the patients' menopausal status nor BMI index. The univariate logistic regression showed a blood cadmium concentration above the median to be associated with an increased risk of endometrial cancer (OR = 5.25; 95% CI 1.56, 17.72). No significant associations were observed between the Pb concentration or Cd/Pb ratio and endometrial cancer risk.

CONCLUSION

The concentration of Cd varies in patients diagnosed with different uterine pathologies. Increased blood cadmium concentration seems to be a risk factor for endometrial studies. Further research on greater populations, accounting for environmental and lifestyle heavy metal exposure, is required to validate our findings.

Serum heavy metals and breast cancer risk: A case-control study nested in the Florence cohort of the EPIC (European Prospective Investigation into Cancer and nutrition) study

BACKGROUND

Chronic exposure to heavy metals is of concern for its potential carcinogenic effect. An association with increased breast cancer (BC) risk was hypothesized, but literature data are conflicting and the question remains unresolved. We aimed to investigate the association between heavy metals and BC risk in a case-control study nested within the Florence section of the EPIC (European Prospective Investigation into Cancer and nutrition) cohort.

METHODS

We included 150 BC cases and an equal number of controls individually matched to cases by age and year of enrolment. In order to avoid confounding by smoking, the study was restricted to never smokers. Serum levels of six heavy metals (Cd, Co, Cr, Mn, Pb, and Tl) were quantified in pre-diagnostic samples using inductively coupled plasma mass spectrometry. Odds ratios (ORs) and corresponding 95 % confidence intervals (CI) were calculated via multivariable conditional logistic regression models.

RESULTS

Serum levels of cobalt were inversely associated with BC risk (OR for the comparison of 3rd vs. 1st tertiles: 0.33, 95 % CI 0.12-0.91, p-value 0.033). None of the other heavy metals under study was significantly associated with BC risk in multivariable models. For Cd, Cr, and Tl, over half of the study participants had serum levels below the limit of quantitation.

CONCLUSIONS

Our results do not support the hypothesis that exposure to heavy metals is associated with an increased BC risk among never smokers from the general population. The inverse association between cobalt serum levels and BC risk requires confirmation in future studies.

Cadmium exposure and risk of breast cancer: A meta-analysis

BACKGROUND

Cadmium is a heavy metal with carcinogenic properties, highly prevalent in industrialized areas worldwide. Prior reviews evaluating whether cadmium influences breast cancer have been inconclusive and not reflected several recent studies.

OBJECTIVE

To evaluate the association between cadmium exposure and female breast cancer incidence, with an emphasis on separately estimating dietary vs. airborne vs. biomarker measures of cadmium and studies published until October 2022.

METHODS

We evaluated risk of bias using set criteria and excluded one study judged to have high risk based on self-report of breast cancer and insufficient adjustment. We conducted a random effects meta-analysis of epidemiological studies, including subgroups by exposure route and by menopausal status.

RESULTS

A total of 17 studies were eligible for our meta-analysis. Only 2 studies addressed airborne cadmium directly. Breast cancer risk was elevated in women exposed to higher levels of cadmium across all studies - pooled odds ratio: 1.13 (95% confidence interval: 1.00, 1.28), with notable heterogeneity between studies (I2 = 77%). When examining separately by exposure route, dietary cadmium was not linked with an elevated risk - (OR: 1.05; 95%CI: 0.91, 1.21; I2 = 69%), consistent with prior reviews, but biomarker-based studies showed an elevated but non-significant pooled measure (OR: 1.37; 95%CI: 0.96, 1.94; I2 = 84%). We did not observe any clear patterns of different risk by menopausal status.

CONCLUSION

Findings from our meta-analysis suggest that exposure to higher cadmium increases the risk of breast cancer in women, but with remaining questions about whether non-dietary exposure may be more risky or whether residual confounding by constituents of tobacco smoke may be at play.

miR-3614-5p downregulation promotes cadmium-induced breast cancer cell proliferation and metastasis by targeting TXNRD1

Cadmium (Cd), which is considered an endocrine disruptor, has been linked to the onset of breast cancer (BC). Our recent study demonstrated that Cd-induced BC progression has a strong correlation with miR-374c-5p dysregulation. The aim of our work was to investigate other potential miRNAs involved in Cd-induced BC cell proliferation and metastasis. In our study, the miRNA profiles of Cd-treated T-47D cells (10 μM, 72 h) were analyzed by miRNA-seq, and our results confirmed that miR-3614-5p was the top downregulated miRNA. Moreover, miR-3614-5p mimic transfection significantly decreased the proliferative ability, migration and invasive ability of BC cell lines (T-47D and MCF-7). Furthermore, we analyzed the overlapping genes from our RNA-seq data and predicted targets from the mirDIP database, and twelve genes (ALDH1A3, FBN1, GRIA3, NOS1, PLD5, PTGER4, RASGRF2, RELN, RNF150, SLC17A4, TG, and TXNRD1) were identified as potential binding targets of miR-3614-5p in the current model. Nonetheless, only miR-3614-5p inhibition caused an increase in TXNRD1 expression upon Cd exposure in T-47D and MCF-7 cell lines. Importantly, luciferase reporter assays further verified that miR-3614-5p suppressed the expression of TXNRD1 by directly binding to the 3'-untranslated region (UTR), and TXNRD1 inhibition significantly repressed the proliferation and metastasis capacity of BC cells upon Cd exposure. Together, our findings demonstrated that Cd exposure repressed the expression of miR-3614-5p, thus activating TXNRD1 expression, which promoted the abnormal proliferation and metastasis of BC cells.

Dietary Trace Element Intake and Risk of Breast Cancer: A Mini Review

Trace elements are essentially required for various physiological and metabolic functions, and any disturbance in the trace elements homeostasis may result in the development of chronic diseases including breast cancer. Breast cancer is the most prevalent cancer type reported in women equally affecting both the high-income and low-income countries. This review therefore aimed to evaluate the impact of dietary trace element intake in relation to the incidence of breast cancer. We focused on five trace elements, thus emphasizing dietary selenium, zinc, iron, copper, and cadmium intake and risk of breast cancer. A systematic approach was applied to perform this review through entering a search term in PubMed and Scopus databases. A total of 24 articles were included after meeting the inclusion and exclusion criteria. Most of the studies regarding dietary iron intake showed a detrimental effect of increased dietary heme iron on breast cancer incidence risk. In addition, there is a limited evidence of high dietary intake of selenium and zinc to reduce the risk of breast cancer. Also, a few studies showed a relationship between high cadmium consumption and risk of breast cancer. More studies related to cadmium and copper exposure are needed to confirm this relationship. As a result, the findings of this review suggested that high dietary heme iron is a potential risk factor for breast cancer.

Metal exposure and breast cancer among Northern Mexican women: assessment of genetic susceptibility

This study aims to assess breast cancer (BC) association with metals and whether polymorphisms in CYP1A1, CYP1B1, GSTM1 and GSTT1 act as confounders or as modifiers of those relationships. We performed a secondary analysis of 499 histologically confirmed BC cases and the same number of age-matched population controls. We measured urinary concentrations of 18 metals with mass spectrometry. We determined the genetic variants of interest by allelic discrimination and multiplex PCR. After adjusting for covariates, we found BC negatively associated with arsenic, barium, cobalt, copper, magnesium, molybdenum and vanadium concentrations and positively with those of caesium, manganese, tin and thallium. Most associations remained after stratifying by the genetic variants. We identified that polymorphisms in CYP1B1, CYP1A1 and GSTM1 genes interacted with some metals on BC: interaction p-values CYP1B1 G119T × antimony= 0.036, CYP1B1 G119T × cobalt <0.001, CYP1B1 G119T × tin= 0.032, CYP1A1 A4889G × aluminium= 0.018, CYP1A1 A4889G × arsenic= 0.031, CYP1A1 A4889G × nickel= 0.036, CYP1A1 A4889G × vanadium= 0.031 and GSTM1 deletion × barium= 0.035. Exposure to various individual metals, along with genetic characteristics may contribute to BC development. Further studies are warranted to confirm our results.

Possible role of lead in breast cancer - a case-control study

Numerous risk factors have been associated with breast cancer (BC), exposure to metalloestrogen, like lead, being such. Since lead involvement in BC is still equivocal, we focused on lead levels in three compartments of BC patients, blood, healthy, and malignant tissues. Also, as the cholesterol role in cancer development was recognized at the beginning of the twentieth century and led to involvement in lipid profile impairment, we further extend our research on lipid profile and enzymes responsible for maintaining lipid balance in BC patients. Fifty-five women diagnosed with BC were enrolled in the study. Forty-one healthy women represented the control group. Lead levels in blood, healthy surrounding and malignant tissue, and lipid profile parameters in serum, were determined. Higher lead levels were obtained in surrounding healthy tissue samples compared to cancerous tissue samples, while blood lead levels of BC women did not differ significantly from the control group. The altered lipid profile scheme in women diagnosed with breast cancer contained significantly higher triglycerides levels (P < 0.001). Moreover, logistic regression analysis revealed triglycerides as a significant predictor of BC (OR = 2.6; P < 0.01). Although statistical significance was missing for lower paraoxonase-1 (PON-1) activities observed in BC women, multivariate logistic regression singled out PON-1 activities as significant BC predictors. The result of the present study further indicated oxidative status imbalance and tissue levels bioelements perturbation. Obtained results in the present study propose possible lead involvement in BC onset accompanied with bioelements redistribution and oxidative stress occurrence.

Breast cancer and urinary metal mixtures in Mexican women

Humans are environmentally exposed to many metals throughout their lives. Simultaneous exposure to several metals could result in synergistic or antagonistic toxicological effects among them; however, the information on exposure to mixtures of metals and breast cancer (BC) is scarce. The objective of this report was to compare metals considered human carcinogens, individually and as mixtures, in women with and without BC. This is a secondary analysis of a population-based case-control study that was carried out from 2007 to 2011 in Northern Mexico. A total of 499 histologically confirmed BC cases and 499 controls were included. Information about sociodemographic, lifestyle and reproductive characteristics was obtained by in-person interviews. Urinary concentrations of aluminum (Al), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), antimony (Sb), cobalt (Co), molybdenum (Mo), tin (Sn), and vanadium (V) were determined by inductively coupled plasma triple quadrupole. Metal mixtures were identified by principal component analysis with creatinine-corrected metals. Over 90% of subjects had metal measurements above the detection limit except tin (86%) and antimony (78.4%). After adjusting by selected covariables, we observed that the individual urinary concentrations of V, Co, and Mo were lower among cases compared to controls; in contrast to Sn that had higher concentrations. We identified two principal component mixtures with opposite relationships with BC: Cr, Ni, Sb, Al, Pb and Sn (OR = 1.15; CI95% 1.06,1.25) and Mo and Co (OR = 0.56; CI95% 0.49,0.64). This is the first study that identified urinary metal mixtures that differed between women with and without BC. Our results warrant confirmation in further prospective epidemiological studies. In addition, the elucidation of underlying mechanisms of metal interactions on BC risk deserves further research.

Breast cancer incidence in a national cohort of female workers exposed to special health hazards in Taiwan: a retrospective case-cohort study of ~ 300,000 occupational records spanning 20 years

OBJECTIVE

Breast cancer is the most common cancer among women worldwide. In Taiwan, workers exposed to any of 31 hazardous chemicals or carcinogens in the work environment are designated as especially exposed workers (EEWs) by Taiwan's Ministry of Labor. We assessed the risk of breast cancer in this nationwide female EEW cohort.

METHODS

We conducted a nationwide retrospective study of 4,774,295 workers combining data collected from Taiwan's Ministry of Labor's EEW database between 1997 and 2018 and Taiwan's Cancer Registry between 1997 and 2016. Standardized incidence ratios (SIRs) for women exposed to different hazards and breast cancer incidence rate ratios (IRRs) were calculated by Poisson regression, adjusting for age and duration of exposure.

RESULTS

3248 female workers with breast cancer and 331,967 without breast cancer were included. The SIRs and adjusted IRRs were 1.27 (95% CI 1.18-1.35) and 1.31 (95% CI 1.21-1.42) for lead, 1.74 (95% CI 1.23-2.24) and 1.52 (95% CI 1.13-2.04) for 1,1,2,2-tetrachloroethane, 1.47 (95% CI 1.12-1.82) and 1.42 (95% CI 1.12-1.81) for trichloroethylene/tetrachloroethylene), 1.40 (95% CI 1.23-1.57) and 1.38 (95% CI 1.22-1.57) for benzene, and 2.07 (95% CI 1.06-3.09) and 1.80 (95% CI 1.10-2.94) for asbestos. The results remained similar when factoring in a 2- or 5-year latency period.

CONCLUSION

This study found possible correlations between occupational exposure to lead, chlorinated solvents (such as 1,1,2,2-tetrachloroethane, trichloroethylene, and tetrachloroethylene), benzene, and asbestos with breast cancer risk among female EEW, suggesting a need for regular screening for breast cancer for employees exposed to these special workplace hazards.

Association between serum folate levels and blood concentrations of cadmium and lead in US adults

BACKGROUND

Folate may be involved in the detoxification of heavy metals. This has been demonstrated in animal studies, in in vivo and in vitro studies, and clinical evaluations. However, knowledge regarding the associations between serum folate and blood concentrations of cadmium and lead is limited.

OBJECTIVE

We aimed to investigate the relationship between serum folate levels and blood concentrations of cadmium and lead in US adults.

METHODS

Data on 15,501 adults were obtained from the 1999-2006 National Health and Nutrition Examination Survey (NHANES) and used for the analysis. Information on serum folate concentrations and blood levels of lead and cadmium was derived from laboratory measurements in the NHANES. Multivariable linear regression was used to examine the relationship between serum folate levels and blood concentrations of cadmium and lead in US adults, controlling for confounders.

RESULTS

The serum folate concentration was negatively correlated with blood levels of cadmium and lead (P-trends <0.01). When stratified by sex (male and female) and estimated glomerular filtration rate (eGFR ≤60 and >60 mL/min/1.73 m²), the association between serum folate concentrations and blood levels of cadmium and lead was found to be more stable in adults with eGFR > 60 mL/min/1.73 m², both in males and females.

SIGNIFICANCE

These findings warrant future studies to explore the mechanisms responsible for the beneficial role of folate in regulating cadmium and lead concentrations in the blood.

N6-methyladenosine-mediated downregulation of miR-374c-5p promotes cadmium-induced cell proliferation and metastasis by targeting GRM3 in breast cancer cells

Cadmium (Cd) is a toxic heavy metal that can facilitate the development and progression of breast cancer (BC). Emerging evidence has indicated that the progression of Cd-exposed BC is related to the dysregulation of microRNAs (miRNAs). The purpose of our study was to investigate the expression pattern and underlying mechanisms of miR-374c-5p in Cd-mediated BC progression. In this study, T-47D cells and MCF-7 cells were treated with different concentrations of Cd (0.1, 1 and 10 μM) for 72 h. MiR-374c-5p expression was downregulated, and transfection of miR-374c-5p mimics significantly decreased BC cell proliferation, migration and invasion induced by 10 μM Cd. Importantly, we used the Cytoscape software plugin cytoHubba to analyse the intersected genes between our RNA-Seq results and the mirDIP database, and six hub genes (CNR1, CXCR4, GRM3, RTN1, SLC1A6 and ZEB1) were identified as potential direct targets of miR-374c-5p in our model; however, luciferase reporter assays indicated that miR-374c-5p only repressed GRM3 by directly binding to its 3'-untranslated region (UTR). Of note, we verified that suppression of N6-methyladenosine (m6A) modification led to miR-374c-5p downregulation by decreasing its RNA transcript stability. Together, these findings demonstrated that m6A modification of pri-miRNA-374c blocks miRNA-374c-5p maturation and then activates GRM3 expression, which drives BC cell metastasis after Cd exposure.

Biochemical composite material using corncob powder as a carrier material for ureolytic bacteria in soil cadmium immobilization

Corncob powder possessing its superiority in environmental sustainability and cost, was approved with strong capability of being a replacement of biochar in facilitating the microbial carbonate precipitation process. In this study, the ureolytic bacterial strain Bacillus sp. WA isolated from a pre-acquired metal contaminated soil in Guiyu, China, was showed to be well attached on the surfaces of corncob powder, indicating the carrier's role as a durable shelter for bacterial cells. The efficient immobilization helped develop biochemical composite material (BCM) and proven to function better the calcite precipitation. Afterwards, the mechanism and multi-directional benefits of BCM in edaphic cadmium remediation were examined through pot experiment and compared with corncob powder/bacterial strain/nutrient media as control groups. Integrated lab-scale analyses emphasized the advantages of BCM by the maximum soil urease activity (up to 3.440 U/mg and increased by 214% in 28 days), maximal bacterial propagation (most abundant population in fluorescence microscopy), richest surface functional group (most remarkable OC bond and CO bond in FTIR result), notable calcite precipitation (clear calcite crystals on the surface of BCM compared to control group under SEM-EDS), and highest Cd immobilization rate (exchangeable Cd decreased by 68.54%), among all treatments. The pH and electroconductivity measurements additionally led to the mechanism of corncob powder and NBU promoting pre-existed ureolytic bacteria in soil, which demonstrated the added value of corncob to be fine carbon source and residence shelter for soil microorganism, revealing its potential in developing agricultural materials.

Metals and Breast Cancer Risk: A Prospective Study Using Toenail Biomarkers

The role of metals in breast cancer is of interest because of their carcinogenic and endocrine-disrupting capabilities. Evidence from epidemiologic studies remains elusive, and prior studies have not investigated metal mixtures. In a case cohort nested within the Sister Study (enrolled in 2003-2009; followed through September 2017), we measured concentrations of 15 metals in toenails collected at enrollment in a race/ethnicity-stratified sample of 1,495 cases and a subcohort of 1,605 women. We estimated hazard ratios and 95% confidence intervals for each metal using Cox regression and robust variance. We used quantile g-computation to estimate the joint association between multiple metals and breast cancer risk. The average duration of follow-up was 7.5 years. There was little evidence supporting an association between individual metals and breast cancer. An exception was molybdenum, which was associated with reduced incidence of overall breast cancer risk (third tertile vs. first tertile: hazard ratio = 0.82, 95% confidence interval: 0.67, 1.00). An inverse association for antimony was observed among non-Hispanic Black women. Predefined groups of metals (all metals, nonessential metals, essential metals, and metalloestrogens) were not strongly associated with breast cancer. This study offers little support for metals, individually or as mixtures, as risk factors for breast cancer. Mechanisms for inverse associations with some metals warrant further study.

Is Cadmium a Risk Factor for Breast Cancer - Results from a Nested Case-Control Study Using Data from the Malmö Diet and Cancer Study

BACKGROUND

Some studies have shown that cadmium (Cd) is associated with breast cancer risk. One hypothesis is that Cd has estrogen-like properties. This case-control study investigated the association between breast cancer risk and blood Cd (BCd) levels.

METHODS

All breast cancers in the Malmö Diet and Cancer cohort were identified through linkage to the Swedish Cancer Registry, baseline (1991-1996) through 2014. Two controls per case were selected from the same cohort. BCd was analyzed at baseline. Associations were analyzed using logistic regression.

RESULTS

Mean BCd was 0.51 μg/L among 1,274 cases and 0.46 among 2,572 controls. There was an overall increased risk of breast cancer [OR, 1.18; 95% confidence interval (CI), 1.05-1.36] per μg/L of BCd. An increased risk was, however, only found at high BCd [OR, 1.34 (95% CI, 1.05-1.73)] for BCd more than 1.20 μg/L. The group with the highest BCd was mainly smokers. A spline indicated that at BCd less than 1.0 μg/L, the OR was not increased. The association with BCd was stronger in current smokers and at body mass index (BMI) above 25, while no modification due to receptor status was found.

CONCLUSIONS

The results indicated increased risk of breast cancer only for high Cd exposure, which occurred mainly among smokers. This made it difficult to disentangle the effects of smoking and Cd, despite inclusion of smoking habits in the models.

IMPACT

This study provides support for reducing Cd exposure through smoking cessation and dietary choice. On the population level, preventive measures against Cd pollution are warranted.

Metabolomic signatures of lead exposure in the VA Normative Aging Study

BACKGROUND

Lead (Pb) is widespread and exposure to this non-essential heavy metal can cause multiple negative health effects; however the mechanisms underlying these effects remain incompletely understood.

OBJECTIVES

To identify plasma metabolomic signatures of Pb exposure, as measured in blood and toenails.

METHODS

In a subset of men from the VA Normative Aging Study, mass-spectrometry based plasma metabolomic profiling was performed. Pb levels were measured in blood samples and toenail clippings collected concurrently. Multivariable linear regression models, smoothing splines and Pathway analyses were employed to identify metabolites associated with Pb exposure.

RESULTS

In 399 men, 858 metabolites were measured and passed QC, of which 154 (17.9%) were significantly associated with blood Pb (p < 0.05). Eleven of these passed stringent correction for multiple testing, including pro-hydroxy-pro (β(95%CI): 1.52 (0.93,2.12), p = 7.18x10^-7), N-acetylglycine (β(95%CI): 1.44 (0.85,2.02), p = 1.12x10^-6), tartarate (β(95%CI): 0.68 (0.35,1.00), p = 4.84x10^-5), vanillylmandelate (β(95%CI): 1.05 (0.47,1.63), p = 4.44x10^-7), and lysine (β(95%CI): 1.88 (-2.8,-0.95), p = 9.10x10^-5). A subset of 48 men had a second blood sample collected a mean of 6.1 years after their first. Three of the top eleven metabolites were also significant in this second blood sample. Furthermore, we identified 70 plasma metabolites associated with Pb as measured in toenails. Twenty-three plasma metabolites were significantly associated with both blood and toenail measures, while others appeared to be specific to the biosample in which Pb was measured. For example, benzanoate metabolism appeared to be of importance with the longer-term exposure assessed by toenails.

DISCUSSION

Pb exposure is responsible for 0.6% of the global burden of disease and metabolomics is particularly well-suited to explore its pathogenic mechanisms. In this study, we identified metabolites and metabolomic pathways associated with Pb exposure that suggest that Pb exposure acts through oxidative stress and immune dysfunction. These findings help us to better understand the biology of this important public health burden.

Blood Transcriptome Response to Environmental Metal Exposure Reveals Potential Biological Processes Related to Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease which is manifested by a progressive and irreversible decline of cognition, memory loss, a shortened attention span, and changes in personality. Aging and genetic pre-dispositions, particularly the presence of a specific form of apolipoprotein E (APOE), are main risk factors of sporadic AD; however, a large body of evidence has shown that multiple environmental factors, including exposure to toxic metals, increase the risk for late onset AD. Lead (Pb) and cadmium (Cd) are ubiquitous toxic metals with a wide range of applications resulting in global distribution in the environment and exposure of all living organisms on earth. In addition to being classified as carcinogenic (Cd) and possibly carcinogenic (Pb) to humans by the International Agency for Research on Cancer, both compounds disrupt metal homeostasis and can cause toxic responses at the cellular and organismal levels. Pb toxicity targets the central nervous system and evidence for that has emerged also for Cd. Recent epidemiological studies show that both metals possibly are etiological factors of multiple neurodegenerative diseases, including Alzheimer's disease (AD). To further explore the association between metal exposure and AD risk we applied whole transcriptome gene expression analysis in peripheral blood leukocytes (PBLs) from 632 subjects of the general population, taken from the EnviroGenomarkers project. We used linear mixed effect models to associate metal exposure to gene expression after adjustment for gender, age, BMI, smoking, and alcohol consumption. For Pb exposure only few associations were identified, including a downregulation of the human eukaryotic translation initiation factor 5 (eIF5). In contrast, Cd exposure, particularly in males, revealed a much stronger transcriptomic response, featuring multiple pathways related to pathomolecular mechanisms of AD, such as endocytosis, neutrophil degranulation, and Interleukin-7 signaling. A gender stratified analysis revealed that the Cd responses were male-specific and included a downregulation of the APOE gene in men. This exploratory study revealed novel hypothetical findings which might contribute to the understanding of the neurotoxic effects of chronic Pb and Cd exposure and possibly improve our knowledge on the molecular mechanisms linking metal exposure to AD risk.

Cadmium and Lead Exposure, Nephrotoxicity, and Mortality

The present review aims to provide an update on health risks associated with the low-to-moderate levels of environmental cadmium (Cd) and lead (Pb) to which most populations are exposed. Epidemiological studies examining the adverse effects of coexposure to Cd and Pb have shown that Pb may enhance the nephrotoxicity of Cd and vice versa. Herein, the existing tolerable intake levels of Cd and Pb are discussed together with the conventional urinary Cd threshold limit of 5.24 μg/g creatinine. Dietary sources of Cd and Pb and the intake levels reported for average consumers in the U.S., Spain, Korea, Germany and China are summarized. The utility of urine, whole blood, plasma/serum, and erythrocytes to quantify exposure levels of Cd and Pb are discussed. Epidemiological studies that linked one of these measurements to risks of chronic kidney disease (CKD) and mortality from common ailments are reviewed. A Cd intake level of 23.2 μg/day, which is less than half the safe intake stated by the guidelines, may increase the risk of CKD by 73%, and urinary Cd levels one-tenth of the threshold limit, defined by excessive ß₂-microglobulin excretion, were associated with increased risk of CKD, mortality from heart disease, cancer of any site and Alzheimer's disease. These findings indicate that the current tolerable intake of Cd and the conventional urinary Cd threshold limit do not provide adequate health protection. Any excessive Cd excretion is probably indicative of tubular injury. In light of the evolving realization of the interaction between Cd and Pb, actions to minimize environmental exposure to these toxic metals are imperative.

Cadmium exposure and risk of breast cancer: A dose-response meta-analysis of cohort studies

BACKGROUND

Cadmium is a toxic heavy metal that has been implicated in breast cancer etiology, albeit with inconsistent results.

OBJECTIVE

To investigate the shape of the relation between cadmium exposure and breast cancer incidence and mortality in cohort studies.

DATA SOURCES

Following a literature search through April 14, 2020, we carried out a systematic review and dose-response meta-analysis to investigate the shape of the relation between cadmium exposure (assessed either through diet or urine excretion) and disease incidence and mortality.

STUDY ELIGIBILITY CRITERIA

For inclusion, a study had to report incidence or mortality for breast cancer according to baseline cadmium exposure category; be a prospective cohort, case-cohort or nested case-control study with a minimum one-year follow-up, and reporting effect estimates for all exposure categories.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were evaluated using the ROBINS-E risk of bias tool. The effects in humans were assessed quantitatively using one-stage dose-response meta-analysis in a random effects meta-analytical model.

RESULTS

We identified 10 studies eligible for inclusion in the dose-response meta-analysis, six based on cadmium dietary intake, and four on urinary excretion levels. We found a marginal and imprecise positive relation between dietary cadmium intake and breast cancer, and no association when urinary cadmium excretion was used for exposure assessment. Compared to no exposure, at 20 µg/day of cadmium intake the summary risk ratio was 1.12 (95% confidence interval 0.80-1.56), while at 2 µg/g creatinine of cadmium excretion the summary risk ratio was 0.89 (95% confidence interval 0.38-2.14). Analysis restricted to post-menopausal women showed no association between either dietary or urinary cadmium and subsequent breast cancer incidence and mortality.

LIMITATIONS AND CONCLUSIONS

Overall, we found scant evidence of a positive association between cadmium and breast cancer. Available data were too limited to carry out stratified analyses according to age, smoking and hormone receptor status. Therefore, possible associations between cadmium exposure and breast cancer in selected subgroups cannot be entirely ruled out.

Cadmium and volumetric mammographic density: A cross-sectional study in Polish women

INTRODUCTION

Cadmium (Cd) is a heavy metal, which is widespread in the environment and has been hypothesized to be a metalloestrogen and a breast cancer risk factor. Mammographic density (MD) reflects the composition of the breast and was proposed to be used as a surrogate marker for breast cancer. The aim of our study was to investigate association between cadmium concentration in urine and mammographic density.

METHODS

A cross-sectional study included 517 women aged 40-60 years who underwent screening mammography in Łódź, Poland. Data were collected through personal interviews and anthropometric measurements. Spot morning urine samples were obtained. The examination of the breasts included both craniocaudal and mediolateral oblique views. Raw data ("for processing") generated by the digital mammography system were analysed using Volpara Imaging Software, The volumetric breast density(%) and fibrograndular tissue volume(cm3) were determined. Cadmium concentration in urine was analysed using the standard ICP-MS method.

RESULTS

After adjusting for key confounders including age, BMI, family breast cancer, mammographic device, season of the year of mammography, and age at menarche, an inverse association of Cd and volumetric breast density was found, which was attenuated after further adjustment for smoking. Associations of Cd with dense volume were null.

CONCLUSIONS

These findings suggest that Cd is not positively associated with breast density, a strong marker of breast cancer risk, when examined in a cross-sectional fashion.

Elemental bioimaging shows mercury and other toxic metals in normal breast tissue and in breast cancers

OBJECTIVE

Exposure to toxic metals such as mercury has been proposed to be a risk factor for the development of breast cancer since some metals can promote genetic mutations and epigenetic changes. We sought to find what toxic metals are present in normal breast tissue and in the tumours of women who had mastectomies for invasive ductal breast carcinoma.

MATERIALS AND METHODS

Formalin-fixed paraffin-embedded blocks from mastectomies for breast carcinoma were examined from 50 women aged 34-69 years. Paraffin blocks selected for elemental analysis were from breast tissue not involved by carcinoma and from the carcinoma itself. Seven micrometer-thick sections were stained with autometallography to demonstrate the presence of mercury, and subjected to laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to confirm the presence of mercury and to detect other toxic metals.

RESULTS

Autometallography-detected mercury was seen in intraductal secretions and some luminal epithelial cells of normal breast lobules in 26 (55%) of the 47 samples where lobules were present, and in 10 (23%) of carcinomas from the 44 samples where carcinoma was present. In eight samples ductal carcinoma in situ was present and one of these contained mercury. LA-ICP-MS confirmed the presence of mercury in samples that stained with autometallography, and detected lead, iron, nickel, aluminium, chromium and cadmium in some samples.

CONCLUSIONS

Mercury was present in normal breast lobules in more than half of mastectomy samples that contained an invasive carcinoma, and in a smaller proportion of carcinomas and ductal carcinomas in situ. Other toxic metals that may interact synergistically with mercury could be detected in some samples. These findings do not provide direct evidence that toxic metals such as mercury play a role in the pathogenesis of breast cancer, but suggest that future molecular biological investigations on the role of toxic metals in breast cancer are warranted.

Endocrine-disrupting metals in ambient air and female breast cancer incidence in US

Metals could act as endocrine disruptors that mimic the actions of hormones, such as estrogens, and contribute to the development and progression of breast cancer. In this study, we examined the association between ambient air emissions of several endocrine-disrupting metals and the incidence of female breast cancer in the United States by analyzing county-level data from national datasets. Linear regression analysis was conducted to evaluate the association in unadjusted and adjusted models. Of the metals analyzed, air emissions of arsenic, cadmium, lead, and mercury, but not chromium VI, were significantly associated with the incidence of all breast cancers, after adjusting for potential confounders. Emissions of arsenic, lead, and mercury were found to be significantly associated with the incidence of estrogen receptor (ER)-positive breast cancer. Among these metals, air emissions of lead showed the strongest association with breast cancer incidence with the β of 3756.66 (95% CI: 1660.29, 5853.03) for all breast cancers and 2433.85 (440.59, 4427.10) for ER-positive breast cancer. Our results demonstrate that exposure to endocrine-disrupting metals in ambient air may be associated with an increased incidence of breast cancer in the United States. Further studies are needed to explore these interactions and to elucidate mechanisms of action.

Toenail-Based Metal Concentrations and Young-Onset Breast Cancer

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a metalloestrogen, and 9 other metals-arsenic, cobalt, chromium, copper, mercury, molybdenum, lead, tin, and vanadium--in relation to young-onset breast cancer (diagnosis age <50 years), which tends to be more aggressive than and have a different risk profile from later-onset disease. Recent metal exposure was measured by assessing element concentrations, via inductively coupled plasma mass spectrometry, in toenail clippings of 1,217 disease-discordant sister pairs in the US-based Sister (2003-2009) and Two Sister (2008-2010) studies. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. After correcting for differential calendar time of sample collection, no statistically significant associations were observed between any metals and breast cancer. Vanadium had the largest odds ratio (for fourth vs. first quartile, odds ratio = 1.54, 95% confidence interval: 0.75, 3.16; P for trend = 0.21). The association between cadmium and young-onset breast cancer was near null, with no evidence of a dose-response relationship (for fourth vs. first quartile, odds ratio = 0.95, 95% confidence interval: 0.64, 1.43; P for trend = 0.64). Positive associations between urinary cadmium concentrations and breast cancer have been reported in case-control studies, but we observed no such association between young-onset breast cancer and toenail concentrations of any assessed metals.

Environmental exposures during windows of susceptibility for breast cancer: a framework for prevention research

Background

The long time from exposure to potentially harmful chemicals until breast cancer occurrence poses challenges for designing etiologic studies and for implementing successful prevention programs. Growing evidence from animal and human studies indicates that distinct time periods of heightened susceptibility to endocrine disruptors exist throughout the life course. The influence of environmental chemicals on breast cancer risk may be greater during several windows of susceptibility (WOS) in a woman’s life, including prenatal development, puberty, pregnancy, and the menopausal transition. These time windows are considered as specific periods of susceptibility for breast cancer because significant structural and functional changes occur in the mammary gland, as well as alterations in the mammary micro-environment and hormone signaling that may influence risk. Breast cancer research focused on these breast cancer WOS will accelerate understanding of disease etiology and prevention.

Main text

Despite the plausible heightened mechanistic influences of environmental chemicals on breast cancer risk during time periods of change in the mammary gland’s structure and function, most human studies of environmental chemicals are not focused on specific WOS. This article reviews studies conducted over the past few decades that have specifically addressed the effect of environmental chemicals and metals on breast cancer risk during at least one of these WOS. In addition to summarizing the broader evidence-base specific to WOS, we include discussion of the NIH-funded Breast Cancer and the Environment Research Program (BCERP) which included population-based and basic science research focused on specific WOS to evaluate associations between breast cancer risk and particular classes of endocrine-disrupting chemicals—including polycyclic aromatic hydrocarbons, perfluorinated compounds, polybrominated diphenyl ethers, and phenols—and metals. We outline ways in which ongoing transdisciplinary BCERP projects incorporate animal research and human epidemiologic studies in close partnership with community organizations and communication scientists to identify research priorities and effectively translate evidence-based findings to the public and policy makers.

Conclusions

An integrative model of breast cancer research is needed to determine the impact and mechanisms of action of endocrine disruptors at different WOS. By focusing on environmental chemical exposure during specific WOS, scientists and their community partners may identify when prevention efforts are likely to be most effective.

Long-term cadmium exposure promoted breast cancer cell migration and invasion by up-regulating TGIF

Cadmium (Cd) is a known human carcinogen. Previous studies have demonstrated that Cd exposure promoted migration and invasion of breast cancer cells. However, the molecular mechanisms underlying this process have not yet been clearly addressed. The purpose of this study was to investigate whether TG-interacting factor (TGIF) was involved in long-term Cd exposure-induced migration and invasion of breast cancer cells. Human breast cancer cells were continuously exposed to Cd for eight weeks. Western blot and qRT-PCR assays were performed to measure the expression of protein and mRNA. Migration and invasion assays were performed to assess the migratory and invasive ability of human breast cancer cells. Our data indicated that long-term Cd exposure obviously increased the expression of TGIF protein and mRNA in human breast cancer cells. Long-term Cd exposure increased the ability of migration and invasion of human breast cancer cells, which could be inhibited by transfection of small interfering RNA (siRNA) targeting TGIF. We also observed that the long-term Cd exposure-induced up-regulation of MMP2 mRNA expression was modulated by TGIF. In conclusion, our findings suggested that TGIF/MMP2 signaling axis might be involved in malignant progression stimulated by long-term Cd exposure in human breast cancer.

Toenail-Based Metal Concentrations and Young-Onset Breast Cancer

Several metals have carcinogenic properties, but their associations with breast cancer are not established. We studied cadmium, a metalloestrogen, and 9 other metals-arsenic, cobalt, chromium, copper, mercury, molybdenum, lead, tin, and vanadium--in relation to young-onset breast cancer (diagnosis age <50 years), which tends to be more aggressive than and have a different risk profile from later-onset disease. Recent metal exposure was measured by assessing element concentrations, via inductively coupled plasma mass spectrometry, in toenail clippings of 1,217 disease-discordant sister pairs in the US-based Sister (2003-2009) and Two Sister (2008-2010) studies. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals. After correcting for differential calendar time of sample collection, no statistically significant associations were observed between any metals and breast cancer. Vanadium had the largest odds ratio (for fourth vs. first quartile, odds ratio = 1.36, 95% confidence interval: 0.84, 2.21; P for trend = 0.17). Cadmium was associated with a small increase in risk, with no evidence of a dose-response relationship (for fourth vs. first quartile, odds ratio = 1.15, 95% confidence interval: 0.82, 1.60; P for trend = 0.67). Positive associations between urinary cadmium concentrations and breast cancer have been reported in case-control studies, but we observed no such association between young-onset breast cancer and toenail concentrations of any assessed metals.

Interactive Effects between Chronic Lead Exposure and the Homeostatic Iron Regulator Transport HFE Polymorphism on the Human Red Blood Cell Mean Corpuscular Volume (MCV)

Research has shown that long-term exposure to lead harms the hematological system. The homeostatic iron regulator HFE (hemochromatosis) mutation, which has been shown to affect iron absorption and iron overload, is hypothesized to be related to lead intoxication in vulnerable individuals. The aim of our study was to investigate whether the HFE genotype modifies the blood lead levels that affect the distributions of serum iron and other red blood cell indices. Overall, 121 lead workers and 117 unexposed age-matched subjects were recruited for the study. The collected data included the blood lead levels, complete blood count, serum iron, total iron binding capacity, transferrin, and ferritin, which were measured during regular physical examinations. All subjects filled out questionnaires that included demographic information, medical history, and alcohol and tobacco consumption. HFE genotyping for C282Y and H63D was determined using polymerase chain reaction and restriction fragment length polymorphism (PCR/RFLP). The mean blood lead level in lead workers was 19.75 µg/dL and was 2.86 µg/dL in unexposed subjects. Of 238 subjects, 221 (92.9%) subjects were wild-type (CCHH) for HFE C282Y and H63D, and 17 (7.1%) subjects were heterozygous for a H63D mutation (CCHD). Multiple linear regression analysis showed that blood lead was significantly negatively associated with hemoglobin (Hb), mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular volume (MCV), whereas the HFE variant was associated negatively with MCV and positively with ferritin. An interactive influence on MCV was identified between blood lead and HFE variants. Our research found a significant modifying effect of the HFE variant, which possibly affected MCV. The HFE H63D heterozygous (CCHD) variant seemed to provide a protective factor against lead toxicity. Future studies should focus on competing binding proteins between iron and lead influenced by gene variation.