Lead

Overview

Lead is a purely toxic heavy metal with no known biological function. It is the most extensively studied metal in relation to neurodevelopmental harm and is increasingly recognized as a contributor to chronic disease across virtually every organ system, even at levels once considered safe. Its toxicity operates primarily through calcium mimicry, heme biosynthesis disruption, and oxidative stress [1], [2]. No level of lead exposure can be considered safe [3], [4].

What sets lead apart from other toxic metals is its ability to infiltrate calcium-dependent signaling pathways throughout the body. Because Pb(II) mimics Ca2+, it enters cells through calcium channels, accumulates in bone as a long-term reservoir, crosses the blood-brain barrier, and disrupts neurotransmission, enzyme function, and gene expression at concentrations far below those that produce overt symptoms [5], [6]. Approximately 99% of blood lead is protein-bound, and bone serves as the primary long-term reservoir with a half-life of decades [5].

What Wikipedia does not cover is lead's profound disruption of the gut microbiome — its role as a selective pressure favoring pathogenic taxa, its destruction of the intestinal barrier, the bidirectional relationship in which dysbiosis impairs the microbiome's own capacity for lead detoxification, and the co-selection of antibiotic resistance genes under lead pressure.

Biological Roles

Lead has no biological role. It is purely toxic. Unlike essential metals such as iron, zinc, and copper, lead is not a required cofactor for any known enzyme or biological process. Its toxicity arises entirely from its ability to mimic and displace essential divalent cations [1].

Calcium Mimicry and Mis-metallation

Lead competes with Ca2+ for binding sites on ion channels, transporters, and intracellular proteins. This disrupts neurotransmitter release at GABA and glutamate receptors, cell adhesion, signal transduction, protein folding, and apoptosis [2], [5]. Lead binds to erythrocytes and readily crosses both the blood-brain barrier and the placental barrier, disrupting neurotransmission and Ca-dependent processes in the developing brain [6].

DMT1-Mediated Transport and Iron Competition

Pb uses the divalent metal transporter DMT1 (SLC11A2), which is also the primary iron importer. Iron deficiency upregulates DMT1 and dramatically increases Pb absorption, explaining why iron-deficient children have disproportionately higher blood lead levels [4]. In the brain, lead competes with iron and manganese for DMT1 transport in dopaminergic neurons, directly linking Pb exposure to iron dysregulation and potential ferroptosis [7].

Heme Biosynthesis Disruption

Pb inhibits two critical enzymes in the heme synthesis pathway: aminolevulinic acid dehydratase (ALAD) and ferrochelatase. This blocks heme synthesis, causes anemia, and accumulates the neurotoxic precursor aminolevulinic acid (ALA) [1].

Oxidative Stress Cascade

Lead depletes GSH, SOD, CAT, and GPx while increasing lipid peroxidation (MDA) and H2O2. At 500 mg/L PbA, these changes are measurable in liver and kidney tissue [1]. In PCOS patients, serum Pb was significantly elevated alongside depleted glutathione and SOD (both P < 0.001), with strong negative correlations between Pb and GSH levels [8].

Zinc Displacement

Lead competes with zinc for protein binding sites, effectively creating functional zinc deficiency. This is proposed as a unifying mechanism in autism spectrum disorder, where toxic metals reduce zinc bioavailability by competing for protein binding sites, producing overlapping gut pathologies including barrier dysfunction, increased permeability, inflammation, and dysbiosis [9], [10], [11].

Epigenetic Modification

Early-life Pb exposure produces latent effects on gene expression through DNA methylation changes. Pb promotes amyloid-beta accumulation through APP gene demethylation: early-life exposure leads to hypomethylation of the APP gene, causing overexpression of amyloid precursor protein that manifests decades later [12], [13], [3].

Dietary and Environmental Sources

Environmental Sources

Contaminated soil (legacy leaded gasoline, paint), drinking water (lead pipes and solder), and ambient air near industrial sites remain major exposure pathways [14]. Occupational sources include battery manufacturing, smelting, mining, and construction or demolition of older buildings [15]. Korean adults carry substantially higher blood lead levels than US, Canadian, or European populations (1.58 vs 0.86 ug/dL), reflecting regional variation in exposure history [16].

Dietary Sources

Diet is the main exposure source for non-professionally exposed populations [6]. Baby foods and infant formulas contain detectable lead at low but measurable levels. All 10 commercial baby food products tested from Houston, TX contained lead (0.0-0.008 ug/g), with contamination originating from food type and soil rather than packaging [17]. Baby food jars from Tenerife, Spain showed lead levels producing margin of exposure (MOE) values of 112.5-450, far below the safe threshold [18]. Approximately 60% of ingested heavy metals are absorbed in the intestine [19].

Consumer Products and Socioeconomic Gradient

Tampons contain detectable Pb [20]. Some traditional remedies and cosmetics are additional sources [14]. Elevated levels are more common in populations with lower education, lower income, and smoking [21].

Microbiome Interactions

This section covers what is arguably the least appreciated dimension of lead toxicity: its profound and bidirectional interaction with the gut microbiome. This relationship is central to understanding why lead produces different disease outcomes in different individuals, and it is content that cannot be found on Wikipedia.

Gut Barrier Destruction

Lead directly damages the intestinal barrier by reducing colonic MUC2, ZO-1, claudin-1, and occludin — the core tight junction proteins that maintain gut integrity [22], [19]. This barrier breach creates a vicious cycle: lead damages the gut, allowing more lead and other metals to enter systemic circulation, amplifying the original insult [23].

Dysbiosis Pattern

Lead exposure consistently alters gut microbiome composition in a dose-dependent and time-dependent manner. Across animal and human studies:

  • Enriched taxa: Firmicutes, Bacteroidetes (phylum level); Enterobacteriaceae (family level) [23], [5]
  • Depleted taxa: Lactobacillaceae, Lachnospiraceae, Ruminococcaceae, Oscillibacter, Ruminococcus, Coprococcus, Blautia [23], [24], [25]
  • Cross-metal pathobiont: Collinsella is enriched across multiple metal exposures including lead, and Desulfovibrio is enriched across metal exposures, contributing to hydrogen sulfide production and further barrier damage [26]
  • Akkermansia muciniphila is decreased under lead exposure, removing a critical mucus layer protector [27]

In an 8-week exposure study in Balb/C mice (100 or 500 ppm Pb), decreased Lachnospiraceae and Ruminococcaceae coincided with increased oxidative stress and defense/detoxification metabolic pathways [25].

Metabolic Disruption

Lead exposure reduces vitamin E, primary bile acids, cholesterol, and coprostanol in the gut metabolome [28]. Depletion of butyrate-producing bacteria (Coprococcus, Roseburia) under lead exposure reduces SCFA availability for colonocyte energy and barrier maintenance [29], [23]. The metabolic disruption extends beyond the gut: heavy metal load in children correlated with elevated microbiome-associated catecholamine precursor metabolites (phenylalanine, tyrosine, L-dopa derivatives), accounting for 32% of variance in social behaviors [30].

The Bidirectional Relationship

The relationship between lead and the gut microbiome is bidirectional: lead drives dysbiosis, and dysbiosis impairs the microbiome's capacity for lead detoxification — a positive feedback loop [27], [24]. The gut microbiota is the first line of defense against heavy metal toxicity, bioaccumulating, binding, and transforming metals via enzymatic reactions to facilitate fecal excretion [27]. Specific mechanisms include siderophore production by Pseudomonas aeruginosa, sulfide production by sulfate-reducing bacteria, and metal transport proteins [27].

When this detoxification capacity is compromised — for example, by a high-fat diet that depletes Lactobacillus — less metal is excreted via feces and more enters systemic circulation. High-fat diet mice accumulated significantly more lead in kidney tissue with more severe renal damage, and excreted less metal via feces, compared to normal-diet controls receiving the same lead dose [29].

Prenatal Exposure and the Developing Microbiome

Prenatal Pb exposure negatively affects child gut microbiome composition years later, particularly Bacteroides caccae [31]. A systematic review of over 3,000 subjects confirmed that prenatal lead specifically depleted Bifidobacterium bifidum and B. longum — the same species depleted in infants who go on to develop type 1 diabetes [26]. In infants, lead is among the metals that shape gut microbial community structure, with different metals selecting for different organisms — a direct demonstration that metal exposure patterns predict microbial community composition [32].

Antibiotic Resistance Gene Enrichment

A particularly concerning dimension of Pb-microbiome interaction is the co-selection of antibiotic resistance. In CKD patients from mining regions in Chile, lead-resistant gut bacteria simultaneously carried resistance genes to gentamicin, cefazolin, ceftazidime, and ciprofloxacin — a co-resistance pattern driven by shared resistance mechanisms on mobile genetic elements [33]. More broadly, lead accumulating in the environment triggers co-selection of antibiotic resistance through shared efflux pumps, biofilm formation, and intracellular sequestration mechanisms. Providencia vermicola sequesters lead via the plasmid-borne bmtA gene, and Vibrio harveyi bioprecipitates Pb2+ as Pb9(PO4)6 [34].

Nutritional Immunity

Lead has no essential biological function, so the host does not sequester it through classical nutritional immunity pathways the way it sequesters iron or zinc. However, lead intersects with nutritional immunity indirectly:

  • Iron sequestration amplifies lead toxicity: When the host upregulates hepcidin and sequesters iron (as in infection), DMT1 expression increases to compensate, inadvertently increasing lead absorption [4].
  • Glutathione depletion: Lead depletes the host's primary metal-detoxification molecule, glutathione. PCOS patients with elevated Pb showed significantly decreased GSH (6.24 vs 8.09 mg/ml, P < 0.001) with strong negative correlations between Pb and GSH [8].
  • Alpha-klotho mediation: Alpha-klotho, an anti-aging renoprotective protein, mediates the relationship between low-dose metal exposure and chronic kidney disease risk. Lead had a posterior inclusion probability of 0.608 in a Bayesian kernel machine regression model of CKD risk, and alpha-klotho mediates the metal-CKD association through antioxidant enzyme regulation, NF-kappaB inhibition, and autophagy promotion [35].

Conditions Associated

Nervous System

Blood lead levels >10 ug/dL affect IQ in children [2]. Even low blood Pb measured at ages 7-8 is associated with more autistic behaviors at ages 11-12 [5]. Higher tibia lead (cumulative lifetime exposure) is associated with cognitive decline in older adults [13]. Lead workers show respiratory symptoms, reduced PFT values, elevated BLL, and serum IgE [1]. See developmental metal vulnerability for critical windows of neurodevelopmental susceptibility.

Alzheimer's Disease and Dementia

Lead is the most extensively studied metal for AD risk, with 21 mechanistic studies in a recent review alone — more than any other metal [36]. Cumulative bone lead (tibia/patella) provides better exposure estimates than blood lead for late-life risk [13]. Early-life Pb exposure produces latent AD-related gene expression changes via epigenetic mechanisms including APP gene hypomethylation and BACE1 activity upregulation [12], [3]. Approximately 95% of AD cases are sporadic with no observable family history, suggesting environmental factors like metal exposure play significant roles [3].

In brain metallomic profiling, lead is among the metals measured that distinguish neurodegenerative disease subtypes. PCA/PLS-DA of multi-element brain profiles achieves clear separation between Alzheimer's disease, dementia with Lewy bodies, and Parkinson's disease dementia, demonstrating that diseases have diagnostically distinct metallomic signatures [37].

Autism Spectrum Disorder

Lead is consistently elevated in hair, blood, teeth, and nails of ASD children. Hair lead was dramatically elevated in severe ASD (1.778 vs 0.881 ug/g in controls, P < 0.001), with a dose-dependent relationship to severity [38], [10]. The gut-brain axis disruption model posits that Pb alters gut microbiota, increases neuroinflammation via microglial activation, and disrupts GABA/glutamate balance through calcium mimicry [5]. Children with the lowest social behaviors had a sixfold increase in odds of high heavy metal loads [30].

A PRISMA systematic review of 37 controlled studies confirmed that lead, mercury, cadmium, and zinc deficiency produce overlapping gut pathologies — barrier dysfunction, permeability, inflammation, and dysbiosis. The unifying mechanism: toxic metals reduce zinc bioavailability through protein-binding competition, mimicking zinc deficiency, with 30-70% of children with ASD suffering some form of GI disturbance [9].

Parkinson's Disease

Chronic lead exposure is associated with elevated PD risk in epidemiological analyses. Lead-induced gut microbiome alterations mirror PD-characteristic patterns (increased Enterobacteriaceae, decreased Lactobacillaceae), and lead's competition with iron and manganese for DMT1 in both the gut and the substantia nigra creates a "double hit" scenario where lead both directly damages neurons and indirectly promotes neurodegeneration through gut dysbiosis [7], [23].

Chronic Kidney Disease

Elevated blood Pb (>=1.5 ug/dL) is independently associated with increased CKD risk (OR 1.41, 95% CI 1.15-1.74) [21]. CKD patients have higher blood Pb but lower urinary Pb excretion, suggesting reduced elimination creates a vicious cycle [39]. Black race significantly modifies the association: 0.13 ug/dL more Pb per 10 mL/min lower eGFR in Black vs 0.03 in White participants [39].

Pb causes mitochondrial damage, GSH depletion, NF-kappaB activation, and renin-angiotensin system activation in the proximal tubule [4]. A longitudinal study with 4 repeated measurements (n=384, 2016-2021) confirmed synergistic effects between Pb, Cd, and Cr on renal biomarkers: the triple Pb-Cd-Cr interaction was significant for urinary albumin-to-creatinine ratio (UACR), and females and smokers showed higher kidney damage at the same exposure levels [40].

A paradoxical finding in environmentally vulnerable areas of Korea: eGFR appeared to increase with higher heavy metal levels, likely reflecting the reverse causality of impaired kidneys reducing metal excretion rather than metals improving kidney function [16].

Cardiovascular Disease

An overview of 8 systematic reviews (153 studies, ~160,000+ participants) confirmed that Pb exposure above 10 ug/dL drives oxidative stress via ROS, inhibits NO bioavailability, reduces Na+/K+ ATPase and myofibril phosphorylation, disrupts elastin synthesis, and disturbs Cu/Zn homeostasis in the cardiovascular system. Mortality risk rises 5.9-fold at Pb >10 ug/dL in CKD patients [41]. Hypertension, CAD, PAD, heart failure, and stroke are all associated with elevated lead levels [41].

Reproductive System

Blood Pb is associated with female infertility, particularly in ages 35-44 and BMI >= 25 (OR 2.62, 95% CI 1.19-5.77) [42]. A two-fold increase in blood lead is associated with a 2.60-fold increased odds of infertility (95% CI 1.05-6.41), and even at very low geometric mean levels (Pb = 0.50 ug/dL), associations remain significant [43]. Lead is elevated in PCOS patients (23.1 vs 15.5 ppb, P < 0.001) with positive correlation to TNF-alpha and HsCRP [44]. Lead also shows a weak but consistent association with higher odds of elevated depressive symptoms during pregnancy [45].

Serum lead is significantly associated with increased bacterial vaginosis risk (OR = 1.35, 95% CI: 1.06-1.72, P = 0.016 for highest tertile) in a dose-response relationship across 2,493 women, likely through endocrine disruption of the hormonal milieu that maintains vaginal Lactobacillus dominance [46].

Breast Cancer

Cu, Cd, and Pb concentrations are higher in breast cancer patients in all biological specimens. Pb activates ERa and the Ras/Raf/MEK/ERK pathway, functioning as a metalloestrogen [47].

Rheumatoid Arthritis and Fibromyalgia

Pb, Cd, and Cr are significantly elevated in both RA and fibromyalgia patients. Pb inversely correlates with vitamin D and directly correlates with DAS28 disease activity score [48]. In a large NHANES analysis (n=14,319), lead showed a negative SHAP value for arthritis overall, though arsenic metabolites and tungsten were the strongest positive predictors for RA specifically [49].

Depression

Lead and cadmium had stronger impact on depressive symptoms in women than mercury in BKMR single-variable analysis. Higher quantile levels of combined metal and behavioral exposures were associated with increased depression risk in a mixture-effects model [50].

Thyroid Disease

Lead may interfere with the thyroid gland directly or indirectly by influencing iodine intake. A link between thyroid volume and Pb concentrations has been proposed, and exposure to combinations of heavy metals rather than single metals may account for thyroid toxicity. Cadmium, arsenic, nickel, and lead are classified as endocrine-disrupting chemicals (EDCs) with thyroid-disrupting potential [51], [52].

Gastrointestinal Conditions

Lead exposure paradoxically can mitigate chemically induced colitis in mice at subchronic (6-week) doses, suggesting hormesis-like immunosuppressive effects [53]. Infant reflux/dysphagia cohorts showed detectable urinary lead, though levels remained below ATSDR toxic thresholds in the study population [54].

Interactions with Other Metals

  • Calcium: Primary interaction — Pb competes with Ca2+ for channels, binding sites, and signaling molecules. Lead enters cells through calcium channels and disrupts all calcium-dependent processes [2], [41].
  • Cadmium: Synergistic nephrotoxicity; combined elevated Pb + Cd mortality risk HR 1.32 (P for interaction < 0.01) [21]. The triple Pb-Cd-Cr interaction is synergistic for UACR [40]. Co-exposure to Pb and Cd at the vaginal level both independently increase bacterial vaginosis risk [46].
  • Zinc: Pb competes with Zn for protein binding sites, effectively creating functional zinc deficiency — proposed as a unifying mechanism in ASD [10], [9]. In the metallome framework, lead displaces zinc from metalloprotein binding sites across the proteome, transcriptome, and epigenome [11].
  • Iron: Pb shares the DMT1 divalent metal transporter with iron; iron deficiency increases Pb absorption [4]. In the brain, lead competes with iron for DMT1 in dopaminergic neurons, linking lead exposure to ferroptosis risk [7].
  • Mercury, Arsenic: Co-exposure to Pb + Cd + As + Hg is the real-world scenario. All four metals consistently disrupt gut microbiota composition, share overlapping dysbiosis phenotypes including Collinsella enrichment, and converge on cardiovascular damage through ROS, endothelial dysfunction, and inflammation [26], [41]. Significant positive intercorrelations among all four metals suggest common co-exposure patterns [8].

Key Studies

SourceEvidence LevelKey Contribution
[9]Systematic reviewPb, Hg, Cd + Zn deficiency produce overlapping gut pathologies; unifying mechanism via zinc displacement
[41]Overview of systematic reviews5.9x mortality at Pb >10 ug/dL in CKD; convergent CVD mechanisms across 4 metals
[26]Systematic reviewPrenatal Pb depletes Bifidobacterium; Collinsella enriched across metals; n=3,000+
[27]Review (keystone)Bidirectional metal-microbiome framework; probiotic detoxification mechanisms
[21]Prospective cohortCombined Pb+Cd shows highest CKD risk (OR 1.65); synergistic mortality
[37]Case-controlBrain metallomic signatures distinguish AD from DLB from PDD
[36]Review21 mechanistic studies on Pb-AD: BBB disruption, neuroinflammation
[40]Prospective cohortTriple Pb-Cd-Cr synergism on UACR; sex and smoking modify effect
[33]Cross-sectionalPb-resistant CKD gut bacteria carry antibiotic resistance genes (co-selection)

Biomarkers

MatrixWhat It ReflectsNotes
Blood lead (BLL)Recent/ongoing exposureMean ~2 ug/dL in US adults; >=1.5 ug/dL associated with CKD risk [21]; Korean mean 1.58 ug/dL [16]
Bone lead (tibia)Cumulative lifetime exposureBest biomarker for AD risk; half-life of decades [13]
Urinary leadRecent excretionLower in CKD patients despite higher blood levels, reflecting impaired elimination [39]
Hair/nailsMedium-term exposureUsed in ASD studies; severity-dependent: 1.778 vs 0.881 ug/g in severe ASD vs controls [38]
Deciduous teethEarly-life exposureUsed in birth cohort studies; accumulate metals during prenatal and early postnatal development [55]

Open Questions

  1. Is there a safe threshold for Pb? Evidence increasingly suggests no — effects are detectable at levels once considered safe, including infertility associations at geometric mean Pb = 0.50 ug/dL [43].
  2. Mechanism of latent neurotoxicity: How does early-life Pb exposure produce AD-related gene expression changes that manifest decades later? The APP hypomethylation pathway is established, but the full epigenetic cascade remains incomplete [3].
  3. Gut microbiome as detoxification buffer: Can restoration of Lactobacillus and other metal-binding commensals reduce systemic Pb body burden? High-fat diet data show that diet-driven microbiome changes alter metal excretion capacity [29], but human intervention trials are lacking.
  4. Racial disparities: Why do Black individuals show greater susceptibility to Pb-CKD associations — is it iron deficiency, vitamin D status, or proximal tubular handling differences [39]?
  5. Metal mixture interactions: How does co-exposure to Pb + Cd + As (the real-world scenario) modify disease risk compared to single-metal exposures? The triple Pb-Cd-Cr synergism on kidney biomarkers suggests non-additive effects [40].
  6. Co-selection of resistance: Does Pb-driven enrichment of antibiotic-resistant gut bacteria contribute to treatment failure in CKD patients with urinary tract infections [33]?
  7. Prenatal exposure windows: At what gestational stage does Pb exposure most strongly affect the child's developing gut microbiome, and is the effect reversible with postnatal intervention [26]?

Cross-References

  • cadmium — synergistic nephrotoxicity, co-exposure in many settings, shared cardiovascular mechanisms
  • arsenic — co-reviewed toxic metal; shared kidney, neurological, and gut microbiome targets
  • zinc — Pb competes with Zn for binding sites; functional Zn deficiency as unifying ASD mechanism
  • copper — co-measured in many disease studies; shared DMT1 transport; Pb disrupts Cu/Zn homeostasis in cardiovascular system
  • mercury — co-reviewed neurotoxin; shared ASD, AD, and PCOS associations; shared gut dysbiosis patterns
  • iron — shared DMT1 transport; iron deficiency amplifies Pb absorption; competition in dopaminergic neurons
  • chromium — co-elevated in RA patients; triple Pb-Cd-Cr synergism in nephrotoxicity
  • nickel — co-measured in RA and cancer studies; co-exposure effects on gut microbiome
  • oxidative stress — central mechanism across all organ systems; GSH/SOD depletion
  • gut-microbiota — Pb-induced dysbiosis, barrier disruption, bidirectional detoxification failure
  • metal carcinogenesis — metalloestrogen activity in breast cancer
  • glutathione — Pb depletes GSH and inhibits GSH-dependent antioxidant enzymes
  • mis metallation — Pb entering via Ca channels and displacing Zn from metalloprotein binding sites
  • neurodegeneration — cumulative Pb exposure associates with cognitive decline and AD risk
  • environmental metal exposure — legacy paint, contaminated soil, water pipes, baby foods, consumer products
  • heavy metals — Pb is the most extensively studied purely toxic heavy metal
  • biomarkers — blood lead level (BLL) is the standard exposure biomarker; bone Pb reflects cumulative dose
  • co selection — Pb drives co-selection of antibiotic resistance genes in gut bacteria
  • developmental metal vulnerability — prenatal and early-life exposure windows
  • ferroptosis — Pb competition with Fe for DMT1 in dopaminergic neurons links to iron-dependent cell death

References (59)

  1. ★Balali-Mood M, Naseri K, Tahergorabi Z et al. (2021). Toxic Mechanisms of Five Heavy Metals: Mercury, Lead, Chromium, Cadmium, and Arsenic. Frontiers in Pharmacology. doi:10.3389/fphar.2021.643972
  2. ★Monisha Jaishankar, Tenzin Tseten, Naresh Anbalagan et al. (2014). Toxicity, Mechanism and Health Effects of Some Heavy Metals. Interdisciplinary Toxicology. doi:10.2478/intox-2014-0009
  3. Jakubowska E, Hoppe-Mitera E, Sionek I et al. (2024). Metal toxicity exposure in Alzheimer's disease - literature review. Journal of Education, Health and Sport
  4. Sabath E, Robles-Osorio ML (2012). Renal health and the environment: heavy metal nephrotoxicity. Nefrologia. doi:10.1212/WNL.0000000000013121
  5. ★Tizabi Y, Bennani S, El Kouhen N et al. (2023). Interaction of Heavy Metal Lead with Gut Microbiota: Implications for Autism Spectrum Disorder. Biomolecules. doi:10.1590/0001-37652022202294S4
  6. ★Guevara-Ramirez P, Tamayo-Trujillo R, Cadena-Ullauri S et al. (2024). Heavy metals in the diet: unraveling the molecular pathways linked to neurodegenerative disease risk. Food and Agricultural Immunology
  7. Yoram Finkelstein, Seth Bhatt, Danielle Bhatt (2022). Finkelstein 2022 -- Lead Exposure, Gut Microbiome, and Parkinson's Disease Risk. npj Parkinson's Disease. doi:10.1038/s41531-022-00351-6
  8. Manal Abudawood, Hajera Tabassum, Atheer H. Alanazi et al. (2021). Antioxidant Status in Relation to Heavy Metals Induced Oxidative Stress in Patients with Polycystic Ovarian Syndrome (PCOS). Scientific Reports. doi:10.1038/s41598-021-02120-6
  9. ★O'Grady K, Grabrucker AM (2025). Metal Dyshomeostasis as a Driver of Gut Pathology in Autism Spectrum Disorders. Journal of Neurochemistry. doi:10.1111/jnc.70041
  10. Blazewicz A, Grabrucker AM (2023). Metal Profiles in Autism Spectrum Disorders: A Crosstalk between Toxic and Essential Metals. International Journal of Molecular Sciences. doi:10.3390/ijms24010308
  11. Janelle E. Stanton, Sigita Malijauskaite, Kieran McGourty et al. (2021). The Metallome as a Link Between the 'Omes' in Autism Spectrum Disorders. Frontiers in Molecular Neuroscience
  12. Islam F, Shohag S, Akhter S et al. (2022). Exposure of metal toxicity in Alzheimer's disease: An extensive review. Frontiers in Pharmacology. doi:10.1038/s44439-024-00009-w
  13. ★Bakulski KM, Seo YA, Hickman RC et al. (2020). Heavy Metals Exposure and Alzheimer's Disease and Related Dementias. Journal of Alzheimer's Disease. doi:10.3233/JAD-200282
  14. Jessica Briffa, Emmanuel Sinagra, Renald Blundell (2020). Heavy Metal Pollution in the Environment and Their Toxicological Effects on Humans. Heliyon. doi:10.1016/j.heliyon.2020.e04691
  15. Briffa J, Sinagra E, Blundell R (2020). Heavy Metal Pollution in the Environment and Their Toxicological Effects on Humans. Heliyon. doi:10.1016/j.heliyon.2020.e04691
  16. Jee Hyun Rho, Seungho Lee, Jung-Yeon Kwon et al. (2025). A Comparative Study on the Paradoxical Relationship Between Heavy Metal Exposure and Kidney Function. Diagnostics. doi:10.1352/1934-9556-59.6.459
  17. Garuba OD, Anglin JC, Good S et al. (2024). Evaluation of Heavy Metals in Commercial Baby Foods. Archive of Food and Nutritional Science
  18. Gonzalez-Suarez S, Paz-Montelongo S, Niebla-Canelo D et al. (2022). Baby Food Jars as a Dietary Source of Essential (K, Na, Ca, Mg, Fe, Zn, Cu, Co, Mo, Mn) and Toxic Elements (Al, Cd, Pb, B, Ba, V, Sr, Li, Ni). Applied Sciences
  19. ★Liliana Anchidin-Norocel, Oana C. Iatcu, Andrei Lobiuc et al. (2025). Heavy Metal-Gut Microbiota Interactions: Probiotics Modulation and Biosensors Detection. Biosensors. doi:10.3390/bios15030188
  20. Jenni A. Shearston, Kristen Upson, Milo Gordon et al. (2024). Tampons as a Source of Exposure to Metal(loid)s. Environment International. doi:10.1016/j.envint.2024.108899
  21. Kuo PF, Huang YT, Chuang MH et al. (2024). Association of low-level heavy metal exposure with risk of chronic kidney disease and long-term mortality. PLOS ONE
  22. ★Sweta Ghosh, Syam P. Nukavarpu, Venkatakrishna Rao Jala (2023). Effect of Heavy Metals on Gut Barrier Integrity and Gut Microbiota. Metal ions in Life Sciences (Accepted Manuscript)
  23. Pengya Zhang, Huizhen Zheng, Guangbo Qu (2021). Zhang 2021 -- Lead Exposure and Gut Microbiome Alterations in Neurodegeneration. Microbiome. doi:10.1186/s40168-021-01012-1
  24. ★Qinheng Zhu, Boyan Chen, Fu Zhang et al. (2024). Toxic and Essential Metals: Metabolic Interactions with the Gut Microbiota and Health Implications. Frontiers in Nutrition. doi:10.1016/j.biopha.2023.115602
  25. Rosenfeld CS (2017). Gut dysbiosis in animals due to environmental chemical exposures. Frontiers in Cellular and Infection Microbiology. doi:10.3389/fcimb.2017.00396
  26. Fatemeh Rezazadegan, Maryam Mahmoudi, Seyed Mohammad Mousavi (2025). Rezazadegan et al. 2025 — Heavy Metals and Gut Microbiota: A Systematic Review. Journal of Health, Population and Nutrition. doi:10.1186/s41043-025-00750-4
  27. ★Hui Duan, Leilei Yu, Fengwei Tian et al. (2020). Gut Microbiota: A Target for Heavy Metal Toxicity and a Probiotic Protective Strategy. Science of the Total Environment. doi:10.1016/j.scitotenv.2020.140429
  28. Bei Gao, Liang Chi, Ridwan Mahbub et al. (2017). Multi-Omics Reveals that Lead Exposure Disturbs Gut Microbiome Development, Key Metabolites, and Metabolic Pathways. Chemical Research in Toxicology. doi:10.1021/acs.chemrestox.6b00401
  29. Liu, Liu, Liu et al. (2020). Liu 2020 — High-Fat Diet Affects Heavy Metal Accumulation and Kidney Toxicity via Gut Microbiota. Frontiers in Microbiology. doi:10.3389/fmicb.2020.01604
  30. Kristin Krajewski (2025). Krajewski 2025 -- Heavy metals, noradrenaline/adrenaline ratio, and microbiome-associated hormone precursor metabolites: biomarkers for social behaviour, ADHD symptoms, and executive function in children. Scientific Reports. doi:10.1038/s41598-025-00680-5
  31. Eggers S, Midya V, Bixby M et al. (2023). Prenatal Lead Exposure is Negatively Associated with the Gut Microbiome in Childhood. Frontiers in Microbiology. doi:10.3389/fmicb.2023.1193919
  32. Xing Yan, Jun Qiu, Ruiwen Huang et al. (2025). Yan 2025 — Association Between Infants' Serum Levels of 26 Metals and Gut Microbiota: A Hospital-Based Cross-Sectional Study in China. Frontiers in Microbiology. doi:10.3389/fmicb.2025.1669475
  33. María V. Miranda, Fernanda C. González, Osvaldo S. Paredes-Godoy et al. (2022). Miranda 2022 — Characterization of Metal(loid)s and Antibiotic Resistance in Bacteria of Human Gut Microbiota from CKD Subjects. Biological Research. doi:10.1186/s40659-022-00389-z
  34. Imran M, Das KR, Naik MM (2019). Co-selection of multi-antibiotic resistance in bacterial pathogens in metal and microplastic contaminated environments: an emerging health threat. Chemosphere. doi:10.1016/j.chemosphere.2018.10.114
  35. Liu S, Wang H, Cao Y et al. (2025). The association between low-concentration heavy metal exposure and chronic kidney disease risk through alpha-klotho. Scientific Reports. doi:10.1038/s44439-024-00009-w
  36. ★Giasuddin Ahmed, Md. Shiblur Rahaman, Enrique Perez et al. (2025). Associations of Environmental Exposure to Arsenic, Manganese, Lead and Cadmium on Alzheimer's Disease: A Review of Recent Evidence from Mechanistic Studies. Preprints.org (not peer-reviewed)
  37. ★Melissa Scholefield, Stephanie J. Church, Jingshu Xu et al. (2024). Scholefield et al. 2024 — Brain Metallomic Signatures Distinguish DLB from AD and PDD. Frontiers in Neuroscience. doi:10.3389/fnins.2024.1412356
  38. Xulan Zhou, Xiaochun Xia, Liming Li et al. (2025). Evaluation of Heavy Metals and Essential Minerals in the Hair of Children with Autism Spectrum Disorder and Their Association with Symptom Severity. Biological Trace Element Research
  39. Danziger J, Dodge LE, Hu H et al. (2022). Susceptibility to Environmental Heavy Metal Toxicity among Americans with Kidney Disease. Kidney360. doi:10.1097/MNH.0000000000000991
  40. Yin G, Zhao S, Zhao M et al. (2024). Complex interplay of heavy metals and renal injury: New perspectives from longitudinal epidemiological evidence. Ecotoxicology and Environmental Safety. doi:10.23749/mdl.v114i3.14422
  41. Nucera S, Serra M, Caminiti R et al. (2024). Nucera 2024 — Non-essential heavy metal effects in cardiovascular diseases: overview of systematic reviews. Frontiers in Cardiovascular Medicine. doi:10.3389/fcvm.2024.1332339
  42. Lin J, Lin X, Qiu J et al. (2023). Association between heavy metals exposure and infertility among American women aged 20-44 years: A cross-sectional analysis from 2013 to 2018 NHANES data. Frontiers in Public Health
  43. Lee S, Min JY, Min KB (2020). Female Infertility Associated with Blood Lead and Cadmium Levels. International Journal of Environmental Research and Public Health. doi:10.5772/intechopen.89462
  44. ★Kirmizi DA, Baser E, Turksoy VA et al. (2020). Are Heavy Metal Exposure and Trace Element Levels Related to Metabolic and Endocrine Problems in Polycystic Ovary Syndrome?. Biological Trace Element Research. doi:10.1007/s12011-020-02220-w
  45. Rokoff LB, Cardenas A, Lin PI et al. (2023). Early pregnancy essential and non-essential metal mixtures and maternal antepartum and postpartum depressive symptoms. Neurotoxicology. doi:10.1016/j.neuro.2022.12.005
  46. Yu-Xue Feng, Ming-Zhi Tan, Hui-Han Qiu et al. (2025). Feng 2025 — Heavy Metal Exposure and Bacterial Vaginosis. PLOS ONE. doi:10.1371/journal.pone.0316927
  47. ★Liu L, Chen J, Liu C et al. (2022). Relationships Between Biological Heavy Metals and Breast Cancer: A Systematic Review and Meta-Analysis. Frontiers in Nutrition. doi:10.3389/fnut.2022.838869
  48. Haddad R, Elbeialy A, El Sawy S et al. (2024). Impact of heavy metals on serum vitamin D3 and PTH in fibromyalgia and rheumatoid arthritis and their correlation to disease activity. Research Square (Preprint)
  49. Fan W, Pi Z, Kong K et al. (2024). Analyzing the impact of heavy metal exposure on osteoarthritis and rheumatoid arthritis: an approach based on interpretable machine learning. Frontiers in Nutrition. doi:10.3389/fnut.2024.1422617
  50. Olamide Ogundare, Emmanuel Obeng-Gyasi (2024). Ogundare 2024 — Association of Combined Effect of Metals Exposure and Behavioral Factors on Depressive Symptoms in Women. Toxics. doi:10.3390/toxics12120879
  51. ★Street ME, Shulhai A, Petraroli M et al. (2024). Street et al. 2024 — The Impact of Environmental Factors and Contaminants on Thyroid Function and Disease from Fetal to Adult Life. Frontiers in Endocrinology. doi:10.3389/fendo.2024.1429884
  52. ★Brylinski L, Kostelecka K, Wolinski F et al. (2025). Effects of Trace Elements on Endocrine Function and Pathogenesis of Thyroid Diseases — A Literature Review. Nutrients. doi:10.3390/nu17030398
  53. Breton J, Daniel C, Vignal C et al. (2016). Does oral exposure to cadmium and lead mediate susceptibility to colitis? The dark-and-bright sides of heavy metals in gut ecology. Scientific Reports. doi:10.1038/srep19200
  54. Du N, Du M, Punshon T et al. (2025). Heavy metal exposures in aerodigestive clinic cohort of infants with reflux or dysphagia. Scientific Reports. doi:10.1038/s41598-025-98768-5
  55. Zehra Akdag, Oytun Erbas (2023). Akdag 2023 — Heavy Metal Toxicity: A Potential Risk Factor for Autism. Journal of Experimental and Basic Medical Sciences. doi:10.5606/jebms.2023.1065
  56. Moody EC, Coca SG, Sanders AP (2018). Toxic metals and chronic kidney disease: A systematic review of recent literature. Current Environmental Health Reports. doi:10.1007/s40572-018-0212-1
  57. Bakulski KM, et al. (2025). Contributions of heavy metal exposure to late-onset Alzheimer's disease. (Behavioural Brain Research / related journal). doi:10.1002/alz.71075
  58. ★Federica Giambo, Sebastiano Italia, Michele Teodoro et al. (2021). Influence of Toxic Metal Exposure on the Gut Microbiota (Review). World Academy of Sciences Journal
  59. Aguilera M, Lamas B, Van Pamel E et al. (2021). Editorial: Risk of dietary hazardous substances and impact on human microbiota: possible role in several dysbiosis phenotypes. Frontiers in Microbiology. doi:10.3389/fmicb.2021.669480

Related Articles