A colorless, odorless and tasteless metal found in U.S. drinking water has been linked to an increased risk of heart disease by a major new study.
Columbia researchers examined the health records of 100,000 Californians over 23 years and compared them to their estimated exposure to arsenic in drinking water.
They found that people exposed to high levels of the toxic metal for ten years or more were 42 percent more likely to develop heart disease, even after factors such as high blood pressure, smoking status and exercise habits were taken into account.
Even drinking water containing less than the EPA limit of 10 parts per billion led to a five to twenty percent increased risk of heart disease over time.
This, said study author Dr. Tiffany Sanchez, an environmental and molecular epidemiologist, suggests that current policies regarding the amount of arsenic allowed in drinking water may need to be reexamined.
Dr. Sanchez said, “Our results are novel and encourage renewed discussion about current policy and regulatory standards.”
This map from the United States Geological Survey estimates the areas of the country with higher levels of naturally occurring arsenic in private drinking wells
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Dr. Sanchez said: ‘This study is one of the first to comprehensively describe the risks at exposure levels below the current legal limit.’
It’s unclear how arsenic can cause heart problems, but… older animal studies have shown that this can lead to inflammation that affects the shape of the blood vessels branching from the heart.
Changes in the shape of these blood vessels can affect the way blood flows and, over time, cause damage to the organ.
Arsenic is a naturally occurring heavy metal found in the Earth’s crust and can enter the air, water and soil.
It is most concentrated in groundwater in New England, the northern Midwest and parts of the West. California is one of those states.
The most common way people are exposed to the metal is through drinking water, according to the National Institute of Environmental Health Sciences.
People who use private drinking water sources and do not regularly test for arsenic are at much greater risk than those who get their water from a community water supply.
The Environmental Protection Agency estimates that these utilities provide drinking water to 90 percent of Americans.
When someone is exposed to this tasteless, colorless and odorless substance in large quantities over a long period of time, it can cause damage to the cardiovascular, immune and endocrine systems. It can also accumulate in the liver, kidneys, prostate and bladder.
Still, researchers aren’t sure how much arsenic exposure can lead to heart disease over time.
The new study, which was published in the journal Environmental health perspectives by researchers at the Columbia University Mailman School of Public Health, with the aim of refining this measure.
It included an analysis of 98,250 people who participated in the California Teachers Study, which collected data from more than 100,000 teachers, nurses and other school staff from 1995 through 2018.
It tracked their lifestyle habits, location and health outcomes over time.
The Columbia researchers excluded people over the age of 85 and those who had previously had heart disease. They then compared the teachers’ health data with maps showing the amount of arsenic in drinking water across California.
They looked at both ischemic heart disease and cardiovascular disease.
Ischemic heart disease, also called coronary artery disease, involves reduced blood flow to the hearing due to plaque buildup or blood clots. According to the NIH, this is the leading cause of heart attack.
Cardiovascular disease is a collective term for stroke, heart disease, heart failure and peripheral vascular disease.
A pattern emerged when we looked at the 6,119 cases of ischemic heart disease and 9,936 cases of cardiovascular disease linking arsenic exposure to coronary artery disease. There was no evidence of a link with cardiovascular disease such as stroke.
In the study, they found that arsenic in water was specifically linked to coronary artery disease, but not to other cardiovascular diseases, such as stroke. CAD is the leading cause of heart attack
The current EPA limit for the acceptable amount of arsenic in drinking water is 10 parts per billion (ppb) of water.
About 48 percent of the participants were exposed to less than one ppb of arsenic, and the researchers found that they were not at increased risk of developing heart disease. But people exposed to between one and ten parts per billion were.
When exposed to between one and five ppb, people were five to six percent more likely to develop ischemic heart disease.
When exposed to between five and ten ppb of arsenic, people’s risk of developing ischemic heart disease increased by 20 percent.
Finally, when exposed to levels above the EPA limit, people were 42 percent more likely to develop ischemic heart disease.
In addition to the amount of arsenic, the researchers looked at whether the amount of time someone was exposed to arsenic water mattered. They found that the longer someone was exposed, the greater the risk.
Once they had been exposed for ten years, their risk was about 18 to 20 percent higher than people exposed to arsenic in drinking water for a shorter period.
These findings, while unique in their scope, are not the first to link arsenic exposure to heart disease.
Ischemic heart disease, also known as coronary artery disease or coronary artery disease, occurs when blockages in the blood vessels cause reduced blood flow to the heart. This can be caused by plaque buildup, a blood clot, or a narrowing of the blood vessels
A 2018 study of indigenous people in the US found that people with higher levels of arsenic in their urine were 1.5 times more likely to have high blood pressure and thickened heart muscle.
Both factors are signs that the heart is under stress and can cause heart disease and interruptions in the heart rhythm.
Still, Dr. Sanchez says more research is needed before doctors can conclude that arsenic causes heart problems, and doctors aren’t sure how the metal could cause the increased risk the study shows.
Normally, narrowing of blood vessels and plaque buildup is attributed to poor dietary choices, which cause cholesterol and fat to build up in the bloodstream and clog the tubes of the cardiovascular system.
It is not clear how arsenic could contribute to this.
Dr. Sanchez therefore concluded that their findings are a starting point for further research: ‘We believe that the data and methods developed in this study can be used to support and inform future studies and can be expanded to investigate other drinking water exposure and health outcomes to evaluate.’