Lead Contamination in Fish and Game

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

I’m often asked in lectures if microwaves are safe, to which I respond: not if you drop them on your foot. But otherwise, it matters what you’re putting in them—sweet potatoes and broccoli, or Hot Pockets and Pop Tarts. Similarly, when I was exploring the safety of hot sauces, given their potential for lead contamination, I had the same reaction. It matters what you’re putting it on.

When I think toxic pollutants, the first thing I think of is the aquatic food chain. We know, for example, that giving people even just a seven-ounce portion of a high-mercury fish, like tuna or swordfish, once a week—that’s about a can-and-a-half of tuna’s worth a week—can quadruple mercury levels in the blood within a few months. What about lead?

A dietary intervention with not one, but five, portions a week, “significantly increased…blood concentrations” of toxic metals, including lead. Even though “the background intake of lead was [found to be] disturbingly high,” the seafood intake increased it by about a quarter. But, “[f]rom a public health perspective,” it’s important to recognize that the amount of seafood that they used in that study “far exceed[s] the intake of most populations.”

Lead can also bioaccumulate in other animals. But, half of our dietary exposure to lead probably comes from plant foods. Animals shot with lead ammunition, though, may present a special case.

We know “[l]ead is toxic and…banned from [most] household items in…developed countries”—except for lead ammunition, “now likely the greatest, largely unregulated source of lead that is knowingly discharged into the environment in [America].” But, not just discharged into the environment, but into the meat itself. “People generally reject the idea of injecting toxic substances into food, except when it involves hunting wild game.”

“Eighty percent of ground [venison]” was found to contain lead. No surprise, given the hundreds of metal fragments that end up in deer carcasses “after being shot” with standard, lead-based rifle bullets—”an impossible number of fragments to pick out by hand, especially because some of these fragments are microscopic.”

Using X-rays, researchers have shown that “[d]uring…penetration, expanding [lead] core bullets typically release hundreds or thousands of fragments.” Or, even millions. Tens of millions of microscopic lead particles per gram; so, one serving could have a billion particles, though they were nanoparticles—extremely tiny, about the size of viruses.

The only good lead, though, is no lead. Even “[v]ery low levels of lead exposure can result in [brain and nerve damage], yet most “hunters [may not be] aware about [the] health risks related to consuming meat from [animals] killed with lead ammunition.

Children may be at risk for losing IQ points, which could reduce their future prospects. A common response from hunters, though, when confronted with the risks of lead exposure, may be, look, “I have been hunting for years, and I am fine.”

To which this physician responds: Ah, “but just imagine how smart you could have been.”

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• Outzen M, Tjønneland A, Larsen EH, Hansen M, Andersen KK, Christensen J, Overvad K, Olsen A. Effect of increased intake of fish and mussels on exposure to toxic trace elements in a healthy, middle-aged population. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2015;32(11):1858-66.
• Yaginuma-Sakurai K, Murata K, Iwai-Shimada M, Nakai K, Kurokawa N, Tatsuta N, Satoh H. Hair-to-blood ratio and biological half-life of mercury: experimental study of methylmercury exposure through fish consumption in humans. J Toxicol Sci. 2012 Feb;37(1):123-30.
• Püssa T. Toxicological issues associated with production and processing of meat. Meat Sci. 2013 Dec;95(4):844-53.
• Buenz EJ. Lead Exposure Through Eating Wild Game. Am J Med. 2016 May;129(5):457-8.
• Arnemo JM, Andersen O, Stokke S, Thomas VG, Krone O, Pain DJ, Mateo R. Health and Environmental Risks from Lead-based Ammunition: Science Versus Socio-Politics. Ecohealth. 2016 Dec;13(4):618-622.
• Kollander B, Widemo F, Ågren E, Larsen EH, Loeschner K. Detection of lead nanoparticles in game meat by single particle ICP-MS following use of lead-containing bullets. Anal Bioanal Chem. 2017 Mar;409(7):1877-1885.
• Fachehoun RC, Lévesque B, Dumas P, St-Louis A, Dubé M, Ayotte P. Lead exposure through consumption of big game meat in Quebec, Canada: risk assessment and perception. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2015;32(9):1501-11.

Icons created by Pavel Melnikov, Oliviu Stoian, Benwithpen, Gay Khoon Lay, Nook Fulloption, Jacob Halton, Bakunetsu Kaito, and Yazmin Alanis from The Noun Project.

Image credit: By Dinomite via Wikimedia Commons. Image has been modified.

Motion graphics by Avocado Video

• broccoli
• children
• cognition
• fish
• heavy metals
• hot sauce
• junk food
• lead
• mercury
• microwaving
• safety limits
• seafood
• sweet potatoes
• tuna
• venison