In 11 European cohorts of 100,166 people, long-term exposure to particulate matter constituents, especially road-dust indicators such as potassium, silicon and iron, was associated with more coronary events; metal associations weakened after adjustment for particle mass.
Authors
- Wolf K, Stafoggia M, Cesaroni G, Andersen ZJ, Beelen R, Galassi C, Hennig F, Migliore E, Penell J, Ricceri F, et al. , Epidemiology. 2015
What was studied
The study investigated whether long-term residential exposure to specific chemical constituents of airborne particulate matter (PM), including several metals, is associated with new coronary events such as heart attacks. Long-term PM exposure is known to be associated with cardiovascular illness and death, but less is known about which components of the particles matter. The researchers estimated each participant's long-term home concentrations of PM10, PM2.5 and eight pre-selected elements: copper, iron, nickel, potassium, silicon, sulfur, vanadium and zinc. Concentrations were estimated with land-use regression models. Cohort-specific associations were estimated with Cox proportional hazards models, with and without adjustment for PM mass, and pooled by random-effects meta-analysis.
Who was studied
The analysis pooled 11 population cohorts from Finland, Sweden, Denmark, Germany and Italy. It included 100,166 people followed for an average of 11.5 years, during which 5,157 incident coronary events were identified. A common set of confounders was used in all cohorts.
Most important findings
| Critical Points | Details |
|---|---|
| Potassium most clearly associated | A 100 ng/m³ increase in PM10 potassium was associated with a 6% increase in coronary events (HR 1.06, 95% CI 1.01–1.12), and a 50 ng/m³ increase in PM2.5 potassium with an 18% increase (HR 1.18, 95% CI 1.06–1.32). |
| Other constituents | Estimates for PM10 silicon and PM2.5 iron were also elevated, and all other constituents studied, including the metals copper, nickel, vanadium and zinc, showed positive associations with coronary events. |
| Effect of adjusting for PM mass | When the models were additionally adjusted for PM mass, the estimates decreased for every constituent except potassium. The independent contribution of individual metals therefore could not be clearly separated from that of the particle mass as a whole. |
| Road dust as a likely source | The authors conclude that long-term exposure to PM constituents was associated with coronary events, especially for indicators of road dust. |
Key implications
This large multicentre study supports the view that the chemical makeup of airborne particles, not only their mass, may matter for heart health, and it points to road-dust-related constituents as a particular concern. For metals specifically, the evidence was suggestive rather than conclusive: associations for copper, iron, nickel, vanadium and zinc were positive but weakened once overall particle mass was taken into account. The study concerns inhaled outdoor air pollution, not dietary or product exposure, so it informs air-quality policy rather than limits for metals in food or consumer products.
Citation
Wolf K, Stafoggia M, Cesaroni G, Andersen ZJ, Beelen R, Galassi C, Hennig F, Migliore E, Penell J, Ricceri F, et al. Long-term Exposure to Particulate Matter Constituents and the Incidence of Coronary Events in 11 European Cohorts. Epidemiology. 2015;26(4):565–574. doi:10.1097/EDE.0000000000000300
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
Lead is a neurotoxic heavy metal for which no safe blood lead level in children has been identified. It contaminates food, consumer goods and drinking water, and exposure is linked to cognitive deficits in children, adverse pregnancy outcomes such as preterm birth and low birth weight, and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
Nickel is a widely used transition metal found in alloys, batteries, and consumer products that also contaminates food and water. Oral nickel can trigger eczema flare-ups in people already sensitised to nickel, and EFSA has set a tolerable daily intake of 13 μg/kg body weight based on developmental effects seen in animal studies. EFSA found that high-consuming toddlers and other children generally exceed this intake. Nickel has been measured in placental and umbilical cord blood, and its links to pregnancy outcomes are still being studied, which is why HMTC applies stricter limits to protect vulnerable populations.
Arsenic is a naturally occurring metalloid that ranks first on the ATSDR toxic substances list. Inorganic arsenic contaminates water, rice and consumer products, and exposure is linked to cardiovascular disease, cognitive deficits, low birth weight and cancer. HMTC’s stringent certification applies ALARA principles to protect vulnerable populations.