Researchers found a link between exposure to lead in childhood and the likelihood of developing mental health issues later in life.
In a paper, a team of researchers from Duke University in Durham, North Carolina probed the long-term consequences of the toxic substance. They found that individuals who had high levels of lead in their blood during their childhood developed mental health issues and/or unhealthy personality traits by the age of 38.
The paper was published in the journal JAMA Psychiatry.
Lead Exposure Linked To Mental Health Issues
For the study, the researchers analyzed the data of over 1,000 individuals from New Zeland who were born from 1972 to 1973. Of the number, 579 had their blood tested when they were 11 years old. About 94 percent of them had lead levels higher than 5 micrograms per deciliter of blood.
"These are historical data from an era when lead levels like these were viewed as normal in children and not dangerous, so most of our study participants were never given any treatment for lead toxicity," said Terrie Moffitt, senior author of the study.
New Zealand was one of the countries that added the highest levels of lead to gasoline to maintain engine durability back in the day. The common metal was widely used in a variety of products, including paint, pipes, solder, and cosmetics.
However, over the years, lead has been declared toxic to humans. The World Health Organization said that no level of lead is safe and exposure can lead to a variety of health problems, including high blood pressure and damage to the kidneys. Previous studies also linked lead to behavioral and intelligence deficit.
The researchers assessed the participants' mental health by looking at 11 disorders: alcohol misuse, cannabis dependence, tobacco use, hard drugs, conduct disorder, major depression, generalized anxiety disorder, phobias, obsessive-compulsive disorder, mania, and schizophrenia.
After looking at the psychopathology factor (p-factor), the measurement used to assess mental health, of the participants and comparing it to the lead levels in their blood, the researchers concluded that lead exposure has long-term effects. In fact, it might manifest negative effects to up to three to four decades.
"Lead exposure decades ago may be harming the mental health of people today who are in their 40s and 50s," warned Jonathan Schaefer.
Lead Exposure And Personality
The researchers also involved the family and friends of participants to assess the effects of childhood lead exposure into their personalities as adults. They found that people who had been exposed to high levels of the toxic metal have neurotic tendencies, were less agreeable, and less conscientious.
However, the study has not proven that high levels of lead in the blood could cause mental health problems later in life. It only showed an association that needs to be further investigated.
The researchers hope to probe whether lead exposure in childhood plays a role in the development of neurodegenerative diseases such as Alzheimer's and cardiovascular problems later in life.