How a Santa Cruz toxicologist helped push through a ban on lead ammunition in California

When California’s ban on lead ammunition went into effect on July 1, conservationists across the state breathed a collective sigh of relief. The bullets are a leading cause of death for the endangered California condor, a scavenger that can ingest bullets when it feeds on the carcasses of deer and other animals that have been killed by hunters. Environmental toxicologist Myra Finkelstein and her team at the University of California, Santa Cruz, were the first to definitively link these bullets to the lead poisoning bedeviling the recovery of condor populations along the California coast. She and her colleagues first assessed the frequency of lead poisoning as a cause of illness and death in the birds and then showed that lead in the ammunition had the same chemical signature as that in the birds’ feathers (Proc. Natl. Acad. Sci. U.S.A. 2012, DOI: 10.1073/pnas.1203141109). The data helped push the lead ammunition ban through the state legislature as California Assembly Bill (A.B.) 711. Lauren Gravitz spoke with Finkelstein about her life as an activist before she became an academic and her current focus on other types of birds and toxic threats.

You took an unusual path into research. What led you from postcollege environmental activism to academic research?

I have been interested in trying to help conserve the environment since I was a little kid. I was involved in different kinds of conservation actions, but I felt a bit limited because I didn’t have a very good understanding of the effective solutions.

It really started for me in the early to mid-1990s, when I was on a ship in the Atlantic. It was a very calm day—the ocean was like glass and there was no land in sight. We crossed over a big band of trash with all kinds of things floating in it: bits of nets, plastic bottles, Styrofoam coolers. We were horrified. We asked the captain to switch course, and we started tracking with that band of trash and just pulling it up. It went from horizon to horizon. At that point I just thought, “Oh my gosh, what are we doing? Here I am volunteering my time trying to help save these animals in the ocean, but I don’t know anything about this. What’s going on with all this trash that I can see and then all the contaminants I can’t see?”

How did you make the pivot from activism to science?

I came to UC Santa Cruz and took graduate courses in aquatic chemistry and physical oceanography to just kind of say, “Could I do this?” I started volunteering in a lab that measured contaminants, such as organic chlorines, in different types of environmental samples. And I started volunteering in a lab that worked on trace metals. From there, I applied to graduate school with some professors that I had met while I was here at UC Santa Cruz.

Your work on condors pushed through some important changes in California. How did you identify the sources of lead in the birds?

We used lead isotopic analysis on blood samples from free-flying condors—some lead poisoned, some not—and compared them to blood samples from captive-bred condors that hadn’t yet been released into the wild. Then we tested lead-based ammunition used by hunters in California, as well as ammunition bought at local retail stores. In a few cases, we also had lead fragments that had been recovered from lead-poisoned condors. About 80% of the lead in free-flying condors was best explained by the lead signature of lead-based ammunition, indicating it was the principal source of the birds’ lead poisoning.

I understand you’re also looking at lead poisoning and golden eagles. Does the recent lead ammunition ban affect that work?

Even though California is going to be implementing A.B. 711, no other state in the nation is, and golden eagles are all over. Lead poisoning of scavenging species from ingestion of spent lead ammunition in carcasses is a global problem. I’m interested in understanding how it’s impacting other scavengers—not just condors.

Golden eagles get brought into rehab centers, and they have lead poisoning. But we don’t have enough information to really understand what the rates of lead poisoning are, so I’m looking at feather lead levels, similar to how I did on the condors, and trying to reconstruct the lead exposure history of the golden eagles across the timeline of feather growth. We’re doing a little bit of work with bald eagles as well.

I think that could be really informative to understand how lead-based ammunition use is impacting scavenging species on a more national and global level. Lead is an equal-opportunity killer.

Beyond lead, what other threats to birds are you looking into?

There’s been some work done to estimate the amount of time a plastic piece might sit in a seabird’s stomach, and it could be months. So that got me to think about how the chemicals coming out of the plastics into the bird’s bodies could be a problem.

A lot of the chemicals that are used to make plastic have endocrine-disrupting properties. These can disrupt an animal’s hormone function, impairing their ability to reproduce and survive.

How are you studying this?

I’m working with a nonprofit, Oikonos, that does necropsies on dead seabirds—they open them up and quantify the plastic that’s inside them. They’ve been doing this for years and have a record of how much plastic they found in black-footed albatross stomachs and how much is hard plastic or fishing-line plastic.

We’ve done some preliminary analysis assessing hard plastic that’s coming from fragments that the seabirds ingest and found that it does have estrogenic activity, which is not super surprising. But the fishing line is also showing up as having estrogenic activity. Fishing line is a really big problem in terms of marine debris, and the majority of black-footed albatross ingest it. The potential impact of marine animals ingesting fishing line is concerning and I do not think has received very much attention.

We don’t really have very much information on the biological impact of these chemicals that the plastic leaches. If a large proportion of these birds always have plastic in their digestive tracts, the plastic is always going to be leaching these things, and that could be a pretty significant source of endocrine-disrupting chemicals.

What solutions do you want to see to the plastics problem?

That’s a hard one, because unlike lead-based ammunition, there’s not something else we can just switch to for plastic. So marine plastic is a huge problem. I don’t think that there is an easy solution, but I think that things are changing. Different countries are talking about banning single-use plastic. Straws are becoming banned. There seems to be more awareness. And I think that my contribution could be to help generate information about the longer-term impact.

Lauren Gravitz is a freelance writer. A version of this story first appeared in ACS Central Science: cenm.ag/finkelstein. This interview was edited for length and clarity.