The dangers of firearms are well understood, but their ammunition is the source of a little-known health threat: toxic lead. Brown doctoral student Christian Hoover studies the connection between guns and elevated blood lead levels in America’s children and adults. Host Megan Hall speaks with him about the results of the first national study of this problem, and his advice for gun owners on the healthiest way to minimize lead exposure.

Welcome to Humans in Public Health. I'm Megan Hall.

In the past few years, the field of public health has become more visible than ever before, but it's always played a crucial role in our daily lives. Each month, we talk to someone who makes this work possible. Today, Christian Hoover

Most of us know that lead exposure is bad for our health. To protect us, especially children, the US hasn’t allowed lead in gasoline, house paint, children’s toys, dishware or jewelry for decades.

But there are a few places where lead has stuck around.

Today we’re taking a look at one of the least well known, and most stubborn sources of lead exposure in the US - guns and ammunition.

Christian Hoover is a PhD student in epidemiology at Brown University and one of the few researchers studying how guns expose us to lead. He says it’s pretty simple- that’s what most bullets are made of.

So when you're shooting, pull a trigger, poof, there's this little plume of dust.

That dust contains lots of tiny particles of lead from the bullet.

So you inhale that dust, unless you're in a really, really well ventilated area, and that's your primary exposure, is that inhalation.

But the exposure to lead doesn’t stop there.

Lead, is this really sticky, heavy substance. So it doesn't stay airborne. It will float down, it will land on things, and then it will stay there… that dust settles on your clothes. It settles on your hands, it settles on anything you have in the immediate vicinity, like a phone.

Which makes it really easy to bring it back to your car, your home, and your family.

So like really comfy chairs, car seats that are made with fabric and rugs are huge, huge reservoirs of lead.

If your child sits in that car seat, or hugs you with the clothes you wore while you were shooting, they’re getting exposed to all of that lead too.

Why should people be worried about lead exposure? Could you remind me? Because you kind of hear like a range of effects, and sometimes we're not really clear enough about what lead can do to children and adults.

So the reason that there's always this sort of range is because lead is just pretty catastrophic, both for adults and children. So children are much more at risk because, volume per body mass. They consume much more. They're engaged in hand to mouth behavior, and they're also still growing. The best way to think of it is when you think of milk and how important calcium is. Lead displaces calcium. So anything that calcium impacts, lead impacts as well. So that's growth, that's renal function, that's cognitive skills.

In adults, exposure to lead can also cause aggression, impulsivity, infertility and neurological diseases like Parkinson's or Alzheimer's. Christian was studying these effects among veterans when he started thinking about guns and lead.

part of my responsibilities, in addition to testing a lot of the veterans, was conducting these interviews where we sort of would go over their lead history and try and capture whether anything could have been responsible for what we're seeing. And they were like, I worked on an aircraft carrier, and they used leaded jet fuel. But then a lot of people would be like, oh, and I would hunt. I would regularly hunt. And I remember eventually I was like, Can you – I've heard that come up a couple of times. Why is that noteworthy? And they were like, Oh well, because, like, we use lead bullets.

This was the “ah ha” moment for Christian

Then I suddenly was considering, oh, well, that actually has a ton, there are a ton of implications for that, not just in hunting. And so then I started to dig a little bit, first looking just broadly and seeing an association, and then looking really closely and seeing an association. And then it was like, Oh my gosh, this is real.

That's interesting. So the veterans sort of taught you to,

oh yeah,

like, keep an eye out for this.

Oh yeah, most of the things that I learned are through my work with veterans, and through them sort of walking me through their experiences and understanding that from the perspective of a public health practitioner.

So tell me about what you did after that, when you realized we've got to figure out a way to see the connection between people who own guns and lead exposure.

Yeah, so I submitted a Freedom of Information Act request in Massachusetts to get access to firearm licensure data. And so I was able to capture the number of active class A firearm licenses. So that's the license to own and operate a firearm in Massachusetts. It's active, so the person would have needed to get it within the last five years. So it's not a perfect indicator, but it's pretty close. And I looked at that against the number of cases of blood lead above five micrograms per deciliter.

That number, five micrograms per deciliter is the amount of lead in a child’s blood that was considered high at the time. But the CDC has actually lowered this number since then – they decided that an even smaller amount of lead is still too much. But Christian used the data he had.

And found these really strong associations where the communities that had more gun licenses had more cases of child elevated blood lead levels, despite controlling for all these other factors that we understand, lead in water, lead in paint, other sort of tracking related occupations. And in all cases, guns are the, the highest or second to highest predictor of blood lead levels in these observational studies.

This study was really just a snapshot. Christian was looking at data from just one moment in time. That means it’s tough to draw conclusions from it. So he expanded the study to use historical data, and look at the entire US.

We then picked it up across 10 years subsequently, and then we picked it up across, I think, eight years, across the entire country.

All of these studies showed the same result - children living in a house with a firearm are more likely to have high levels of lead.

Christian isn’t the first person to look into this. Researchers had done small case studies with a handful of people and found similar things. But Christian’s work is the first large-scale study to explore this connection.

So why do you think it took so long to be talking about lead exposure related to guns, like, why is this a new discussion?

Well, … guns have always been a polarizing topic.

Guns are so controversial, some politicians stand in the way of studying them at all. In 1996 congress passed a law that banned the CDC from funding any research that in their words “may be used to advocate or promote gun control.”

And people were sort of like, well, we can't even – we don't want to look at it.

In 2019 a new spending bill made it possible to use federal funds to study guns. But Christian says a lack of financial support isn’t the only reason this topic is so difficult to research.

There's a certain amount, I think, of intimidation that can occur.

Christian says extreme gun advocates often harass researchers online, sometimes going as far as releasing their personal phone numbers and addresses.

You just are a lot more public. People make you public. And so if you are getting into the work to do good in the world, and you don't want all of your personal details online, you know, like that. You can research lead in other areas and not be at that same risk.

Yeah, what has the experience been like for you doing this kind of research?

Well I don't have a social media presence, so that helps. And I think for me, it's actually been pretty refreshing. There are the people who argue that anything that looks at guns is pushing an agenda, but those people are a very vocal group, but very small and backed by a lot of money, but the majority, the vast, vast majority, has an acknowledgement of the of the challenges and the dangers of guns. And pretty much everybody that I've spoken to, they want to be a part of the solution. You know, like gun owners in general they're a very safety oriented group. There is an acknowledgement of the risks from lead exposure. We've known about it for so long, we have so much information on it that we understand it detached from guns, and then are able to understand it connected to guns. And so people, they'll talk to me about it!

Why do we even use bullets with lead anyway? I mean, couldn’t we just use a different type of material?

Yes. Well, there are alternatives. So there's like biomass, which. It is, is better than lead, but… biomass has like PFAs exposure like there are other things that are in it, which are just as bad - you could argue… but there’s copper bullets as well. The challenge is that the guns that are developed today are not designed for any other type of ammunition. So putting a different type of ammunition in your gun is going to lead to greater deterioration of the gun. And so, you know, if people are concerned about a gun working when you need it to work, there's a fear about that

What is your advice to gun owners? What should they be doing to prevent or limit exposure to lead?

Well,yeah, so I would say always make sure that you shoot in a well ventilated area. So if you, if you fire your gun and you notice that the smoke sort of like lingers there for a little bit. That's not a well ventilated area, you want the smoke to drift pretty much immediately away from you. So outdoors is good. There are environmental risks with outdoor shooting. So it's hard for me to sort of endorse that completely. I think it reduces your exposure, but it does introduce it into the environment in a way that's pretty, pretty damaging. I would say, you know, clean your gun in a wide open space. Do not, take it home. If you must take it home, clean it in like a shed. Clean it away from your children. I mean, treat it like what it is – toxic so, you know, whatever your comfort level is with how you would handle toxic materials around your children, that's what you should do. Change your clothes after shooting. And that's not a popular that's not a popular suggestion. I think if you can figure out how to transport your clothes carefully in a bag, wash your hands, and I think just make sure that when you do store your gun and you store your ammunition, that you store them away from your children, not just because of the imminent risk of violent injury, but also because of the exposure risk.

So where do we go from here? Now that you've done this research, it's pretty clear that this is an issue. What are your recommendations?

Well, that's tough. We're not going to legislate our way out of it. Guns are here to stay in the United States, I know, like, there are a lot of people that don't agree with that, and I think that that is it's like, it's hard to do this work and work within these communities and endorse anything other than that. And so a part of of how I like approach this is that I can't I work really hard to not push an agenda, and I work really hard to not say, well, let's just pass a law and then that'll fix it.

States have actually tried to ban lead ammunition. There was an effort in California back in 2017…

And that got shelved really quickly. They were getting calls from everybody, including the Olympics, saying that you can't, you can't ban lead shots. Then how will our Olympic teams train? How will we be competitive on the world stage in shooting?

So, if it’s difficult to pass laws preventing lead bullets, what can be done?

I think that you know where we go from here is that we do more community outreach. I think, It's up to us to figure out how to make adopting non lead shot more enticing. I don't think we can force people, I think we have to make a reasonable case for why they shouldn't, and we have to make the alternative one where the benefits outweigh the costs. And so I think, you know, alternatives to lead shot, they have a long way to go, but I think that that's sort of step one is just trying to encourage people to be mindful of the risks.

Well, Christian, thank you so much for coming in. This was really interesting.

Thanks for having me.

Christian Hoover is a second year PhD student in Epidemiology at the Brown University School of Public Health. He is also a Co-Investigator on the Firearm Exposure Research Team at Harvard T.H. Chan School of Public Health

Humans in Public Health is a monthly podcast brought to you by Brown University School of Public Health. This episode was produced by Nat Hardy and recorded at the podcast studio at CIC Providence.

I'm Megan Hall. Talk to you next month!