A new study suggests that lead exposure may be a significant, overlooked risk factor for cardiovascular disease. It has been estimated that lead exposure may contribute to more than 400,000 deaths of adults each year in the United States. This would mean that lead exposure could be responsible for nearly 10 times more deaths nationwide than previously thought.

The estimate was deduced from a nationally representative sample of over 14,000 adults who had their blood tested for lead between 1988 and 1994. The study found that individuals with an initial blood lead concentration at the 90th percentile had a 37 percent increase in all-cause mortality and a 70 percent increase in cardiovascular disease mortality when compared to those with a blood lead concentration at the 10th percentile. According to the study, the 10th percentile corresponded to a blood lead concentration of 1.0 micrograms per deciliter, while the 90th percentile corresponded to a concentration of 6.7 micrograms per deciliter.

The research suggests that even low-level exposure may be a significant risk factor for heart disease. While lead exposure has long been considered a risk factor for heart disease, this is the first study to quantify the risk. The new study was recently published in The Lancet Public Health.

Dr. Bruce Lanphear, a professor of health sciences at Simon Fraser University and a leading author of the study, said in an interview, “Nobody had even tried to estimate the number of deaths caused by lead exposure using a nationally representative sample of adults. But if we’re underestimating the impact of lead exposure on cardiovascular disease mortality and other important outcomes beyond IQ, then it might have a big impact on the way we make investments in preventing lead poisoning exposure.”

Experts say the results of the study should be interpreted cautiously. The researchers acknowledged that they were not able to account for everything that might contribute to the deaths. The data used in the study measured lead levels in the blood only once, while the concentration of lead in blood can change over time. Other potential risk factors were also assessed only once and not tracked over time.

The CDC and the Environmental Protection Agency have warned that lead is unsafe at any level. Exposure to lead during childhood is known to increase the risk for neurological issues, behavior problems, IQ deficits, and delayed development, as well as hearing and speech problems. People can be exposed to lead through industrial jobs, paint, household dust, food, water, and cigarette smoke.