Lead contamination in drinking water is linked to a number of health issues, including cognitive and learning difficulties, as well as psychiatric disorders. (Photo: Nenad Stojkovic, Flickr, CC BY 2.0)
Lead contamination in drinking water can have serious impacts on growing brains, including cognitive issues in the short term and mental illnesses years after the exposure ends. Kristina Marusic is an investigative reporter with Environmental Health News, which published a 5-part series about how air, water, and climate pollution shape our mental health. She joins Host Bobby Bascomb.
DOERING: From PRX and the Jennifer and Ted Stanley studios at the University of Massachusetts Boston, this is Living on Earth. I’m Jenni Doering
BASCOMB: And I’m Bobby Bascomb.
There is no safe level of exposure to lead yet roughly 186 million Americans are drinking with lead levels above 1 part per billion. That’s the level set by the American Academy of Pediatrics to protect children from lead in school water fountains. Lead contamination in drinking water has been linked to a host of health problems, from anemia, and hearing loss, to learning disabilities especially in children.
And now a growing body of evidence shows a connection between water polluted with lead and mental health problems. Investigative reporter Kristina Marusic has been digging into that relationship as part of a series on mental health and pollution for Environmental Health News. She focused her reporting on Western Pennsylvania, one of the worst regions in the country for lead contamination in water. Kristina Marusic, welcome back to Living on Earth!
MARUSIC: Hi, Bobby, it's great to see you again.
BASCOMB: You know, we know that lead, of course is especially problematic for children and learning disabilities. But our listeners might be surprised to hear about a host of mental health issues associated with elevated lead levels. Can you tell us about some of those, please?
MARUSIC: Yeah, so scientists are just kind of beginning to figure out that, in addition to causing some of those learning and behavioral and cognitive problems in kids who are exposed to lead, the effects of lead exposure can show up as mental illness much, much later in life. So maybe not even until someone who was exposed to lead as a kid reaches middle age. So I spoke with one researcher who led a 2021 literature review that looked at several dozen human and animal studies on lead exposure, and it found increasing evidence that childhood lead exposure is a risk factor for psychiatric disorders in adulthood, including anxiety, depression, obsessive compulsive disorders, and then also for neurodevelopmental disorders like ADHD, autism, and Tourettes syndrome. And the largest one of those studies, so again, he looked at a whole lot of studies in both people and animals to do that literature review, but the biggest one looked at 1.5 million people in the US and Europe, and found that people who had higher lead exposure as kids were more likely to have negative personality traits like lower conscientiousness, lower agreeableness, and higher neuroticism once they reach adulthood, all of which contribute to mental illness.
BASCOMB: So what is the mechanism here by which lead is contributing to mental health problems?
MARUSIC: So scientists are a lot clearer on how lead impacts the brain than they are about air pollution, which they're still kind of trying to figure out. Lead exposure impacts a protein receptor in the brain that's known as the NMDA receptor, and I'll say it but it's a very, very long word. NMDA stands for N-methyl-dextro-aspartatic acid receptor. So we'll stick with NMDA, and that receptor is critically important for brain development, learning and cognitive function. And improper functioning of the NMDA receptor is also seen in the brains of people with certain mental illnesses, including schizophrenia. So the NMDA receptor influences the development of inhibitory neurons that help keep the brain balanced. And when it's damaged by lead exposure, it creates too few of those neurons. So you can imagine in a healthy brain, you have excitatory neurons and inhibitory neurons, and they maintain this kind of exquisite balance where, you know, there are an equal amount of both, and it keeps everything in check. And if that's interrupted, and you have too many of one or the other, the balance is thrown off, and that can manifest as mental illness.
BASCOMB: Mm hmm. Well, we last spoke to you regarding your article on air pollution and its effects on mental health. To what extent are these sort of overlapping issues? Do you often see, you know, where you have air pollution, you also have this problem of contaminated drinking water, and to what extent is that, you know, the problem sort of magnified?
MARUSIC: Unfortunately, communities that have problems with childhood lead exposure are also likely to experience other issues that can disproportionately impact people's health. And that includes other environmental exposures like air pollution, which also can impact both physical and mental health. It also includes things like community violence, racism, and poverty. And so all of these factors kind of overlap to create combined physical and mental health impacts, that can be really detrimental. But there's also emerging evidence that one harmful exposure from something like air pollution changes the brain in a way that can magnify the effects of another harmful exposure later on. So scientists are kind of just learning that it might not be an additive effect, where one plus one equals two, but more of a synergistic effect where if you're getting one hit from lead exposure, and one hit from air pollution exposure, they actually combined to be more like three or four hits. So there's a lot of concern that you know, these overlapping impacts are having a magnified effect on these communities that face more than one issue.
BASCOMB: And you're right, that even normalizing for income, unsafe drinking water is more of a concern for many minority communities. What's going on there?
MARUSIC: Yeah, so, some research has shown that regardless of income level, black children in the United States are two to three times as likely as white or Hispanic children to experience lead poisoning. And the thinking is that this is, in part, a lingering effect of racist practices like redlining, where black community members specifically were kept out of certain communities. And that then, you know, as time moved along, these black communities were less likely to have their lead lines replaced, and more likely to deal with other types of pollution and water contamination. So it definitely is an environmental justice issue. If you look at many of the communities that have kind of made headlines for having lead in the drinking water, many of them are majority black communities. So this is a story we see play out again, and again, in the United States.
BASCOMB: We know that there's no safe level of lead. And at the same time, we know that millions of Americans are drinking water that's contaminated with lead. But remediation, you know, replacing those lead pipes is is really expensive. I mean, is that basically what this boils down to, in terms of, you know, creating a safer drinking water system for the country?
MARUSIC: Yeah, so a lot of it comes down to aging infrastructure and the need to replace lead pipes. One of the big challenges there is that, if you replace just part of a lead line, and not the entire water line, it can actually result in more lead being in the water temporarily, because replacing part of the line kind of jostles and shakes loose the part of the line that's left in place in a way that can cause more lead to like flush into homes. So when they replaced lead lines, at least for the the big major main water authority here, not for some of the smaller ones, they are required to do a full lead line replacement at no cost to the homeowners. So if they're replacing the line under the street, they also have to replace the lines that go into everyone's homes at the same time. And if there's a delay, if initially, they replaced the part into the street, they also have to notify people that they should use a filter to make sure that they're not getting exposed to extra lead when it's kind of jostled loose during that process. So there's a lot that goes into that, you know, your question was, is this kind of the fundamental problem and the issue is that there are so many considerations and these projects are big and expensive. You know, a lot of times cities and municipalities are just strapped for cash. And it's just an issue of not having the budget to do all these lead line replacements.
BASCOMB: Kristina Marusic is an investigative reporter with Environmental Health News. Kristina, thank you so much for taking this time with me today.
MARUSIC: It was great talking to you. Thank you.
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