There are almost 412,000 people in the US who die every year because of lead contamination. They number of about 10 times higher than the figure cited by the Institute for Health Metrics and Evaluation at the University of Washington in Seattle.
The researchers monitored over 14,000 adults for two decades. They found that people with an initial blood lead concentration at the 90th percentile had a 37 percent hike in all-cause mortality, CNN reported. They also had a 70 percent increase in heart disease mortality compared to those whose blood lead concentration was at the 10th percentile.
Greater than anticipated
Dr. Bruce Lanphear, a professor of health sciences at Simon Fraser University, noted that while the link between high blood pressure and lead exposure had long been established for decades, the magnitude of its effect on heart mortality, especially at low levels of lead exposure, was greater than anticipated.
He pointed out that no one has estimated the number of deaths that lead exposure caused, using a nationally representative sample of adults. If the impact of lead exposure on cardiovascular ailment mortality was underestimated and the other vital outcomes beyond IQ, it might have a big impact on the way investments are made to prevent lead poisoning exposure, Lanphear said.
He said that low levels of lead exposure are important but largely ignored as a risk factor for death from cardiovascular ailments. Lanphear said the new study challenges the assumption that specific toxicants, such as lead, have safe levels, Newsmax reported.
Battery of tests
The 14,000 adults in the study had blood tests at the beginning of the study to measure their past and current exposure to lead. They also underwent a urine test for metal cadmium. The sources of lead exposure include fuel, paint, plumbing, and smelting sites or handling lead batteries. Drinking water can also be a source of contamination and food stores in lead-tainted containers.
Although safety rules have significantly reduced the risk of lead exposure in recent years, particularly in developed nations, the metal can stay in the body for many years. Nearly one in 10 of the volunteers tested had an undetectable level of lead in their blood, while around one-fifth had at least 5 mg/dl of lead in their veins.
Out of the 18 percent of the people who died from all causes during the period under review, they were discovered to have more than 1 mg/dl of lead in their blood. The researchers concluded that almost 30 percent of all deaths because of cardiovascular diseases, mainly heart attacks and strokes, could be attributed to lead exposure.
Lanphear stressed that lead represents a leading cause of disease and death. He underscored the importance of continuing efforts to reduce environmental lead exposure. The scientists sought more aggressive measures to retire contaminated housing, phase out jet fuels laden with lead, replace the lead pipes in plumbing, and to reduce emissions from smelters and lead battery factories.
No safe levels
Since lead has a deadly effect on multiple organ systems and a relatively low level of exposure was previously thought to be safe, Philip Landrigan, a professor at the Icahn School of Medicine in New York, said that lead has a much greater impact on cardiovascular mortality than recognized previously.
Lanphear added that there was no safe threshold for lead. Once the scientists found that there was a risk across the entire range of exposures, they could estimate the number of attributable deaths. He said that when researchers began looking at the risk across the entire range of people exposed, all of a sudden, the number of affected people jumped.
He noted that there are so many people in the low- to moderate-risk groups that for as long as there are some risks with low-level exposure, many more people are going to die or develop heart disease. The US Centers for Disease Control and Prevention reduced the acceptable blood concentration from 40 micrograms per deciliter in the early 1970s to 10 micrograms per deciliter in the early 1990s to 5 micrograms per deciliter several years ago.
The researchers controlled for other factors that could contribute to cardiovascular diseases such as smoking, excessive alcohol consumption, poor diet, and lack of exercise. But they failed to include the possible effect of exposure to arsenic or air pollution.
Tech Times suggested that to protect the family from exposure to lead, the home should be investigated and repaired. It noted that houses built before 1978 may have used lead paint. Those constructed before 1986 could have water pipes with lead. The website advised parents to have their children tested for lead in their blood.
The kids, after all, are more susceptible to the bad health impact of lead exposure. It may result in behavior problems, delayed development, speech and hearing problems, and IQ deficits. A study published in April 2017 found that one-third of lead poisoning among children in the US goes undiagnosed.
[researchpaper 리서치페이퍼= Vittorio Hernandez 기자]