The researchers found that 20 percent of participants had a concentration of lead of at least 5 µg/dL in blood.
Lead was added to petrol until the 1990s to boost engine compression, and was also widely used to improve the performance of household paint before being banned in the United States in 1978 and the European Union in 1992 "after concerns over the effects it was having on the environment and children's brains", adds the paper.
The findings revealed a link between low-level exposure and increased risk of premature death. A total of 4,422 people died during a median follow-up of 19.3 years: 38 percent from cardiovascular disease and 22 percent from ischemic heart disease.
Up to 412,000 deaths a year in the USA can be attributed to lead exposure, according to a new study published Monday in The Lancet Pubilc Health. "Still, lead represents a leading cause of disease and death, and it is important to continue our efforts to reduce environmental lead exposure".
Additionally, the study took only one reading of lead in participants' blood, when levels were likely to have changed over time.
Tim Chico from the University of Sheffield said: "This study suggests that lead, or factors that increase people's exposure to lead, causes thousands more deaths every year than we previously recognised".
Researchers warned outside factors could lead to an "overestimation of the effect of concentrations of lead in blood, particularly from socioeconomic and occupational factors".
Overall, people who had high lead levels (6.7 µg/dL) were at 37% greater risk of premature death from any cause, 70% times greater risk of cardiovascular death, and double the risk of death from ischemic heart disease, compared with people with lower levels (1 µg/dL).
However, because lead can contribute to conditions such as high blood pressure and hardening of arteries, it is also believed to contribute to cardiovascular and heart disease.
There are regulations in place to safeguard people against lead exposure but about 90 percent of USA are still exposed to the contaminant, CNN noted.
These results were adjusted for age, sex, household income, ethnic origin, diabetes, BMI, smoking status, alcohol consumption, diet, physical activity, and amount of cadmium in urine.
Researchers followed almost 14,300 participants for two decades and discovered that despite previous studies suggesting that low-level lead exposure did not increase the risk of premature death, this might not be the case. "Public health measures, such as [upgrading] older housing, phasing out lead-containing jet fuels, replacing lead-plumbing lines, and reducing emissions from smelters and lead battery facilities, will be vital to prevent lead exposure". For example, they point out that their study relied on a single blood test from each subject at baseline, so they were unable to determine the "effect of further lead exposure". A key conclusion to be drawn from this analysis is that lead has a much greater impact on cardiovascular mortality than previously recognized...