Toxic metals and lung health: silent poisons?

• Published in: Thorax Vol. 79; no. 7; pp. 601 - 602
• Main Author: Shaheen, Seif O
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd and British Thoracic Society 10.04.2024; BMJ Publishing Group LTD
• Subjects: Arsenic; Barium; Cadmium; Clinical Epidemiology; Cognitive ability; Cross-sectional studies; DNA methylation; Editorial; Epidemiology; Ethnicity; Food; Gasoline; Heavy metals; Lead; Population-based studies; Titanium; Toxicity; Urine; United Kingdom > UK; United States > US; China; Clinical Epidemiology
• ISSN: 0040-6376; 1468-3296; 1468-3296
• DOI: 10.1136/thorax-2024-221518

Correspondence to Professor Seif O Shaheen, Wolfson Institute of Population Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK; s.shaheen@qmul.ac.uk Lady Astor: ‘Sir, if you were my husband, I would put arsenic in your tea!’ Churchill: ‘If I were your husband, I would drink it!’ This apocryphal joke is a reminder that arsenic is a potentially fatal poison. For lead, cadmium and arsenic exposure, there is considerable epidemiological evidence, backed up by mechanistic data, implicating these metals as cardiovascular risk factors.5 Cohort studies in US adults reported that higher concentrations of blood lead and urinary arsenic, even at low levels, were associated with higher cardiovascular mortality.6 7 Arsenic and lead exposure in childhood may be neurodevelopmentally toxic, resulting in impaired cognitive function; for lead exposure, this is seen at low exposure levels, with no threshold of risk.8 9 Exposure in utero is likely to be particularly detrimental to child health. In a cross-sectional study of children and adolescents in the USA, higher urinary concentrations of lead and manganese, but not cadmium, were associated with lower mid-expiratory flows.20 Higher blood lead and cadmium concentrations in Korean adults, and higher urine cadmium concentrations in US adults, were associated with a lower FEV1/FVC ratio in cross-sectional studies, indicating airflow obstruction.16 21 A meta-analysis of nine studies of children and adults across multiple LMICs found that higher arsenic exposure was associated with a lower FEV1 and FVC, suggesting restrictive lung function impairment.22 Higher prenatal exposure to arsenic has also been associated with smaller childhood lung volumes (FEV1 and FVC).23 Given the paucity of population-based studies of toxic metal exposure and lung function, the paper from Yu and colleagues in this edition of Thorax24 is a welcome addition to the literature. While titanium dioxide nanoparticles are considered to be inert, given widespread exposure to titanium in everyday life, further data on potential lung toxicity is needed.25 Similarly, whether barium exposure via food and water has health consequences deserves further study.26 The authors acknowledge some study limitations, not least the cross-sectional design, which greatly limits causal inference; also, the potential for residual confounding by smoking, which could have been addressed either through a sensitivity analysis excluding ever smokers, or by adjusting for a pack-year index of lifetime exposure.