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Here's an email I sent to Marrett Grund, a MN DNR researcher who did a very interesting study of lead contamination of deer shot with a variety of different rifle, shotgun, and muzzleloader projectiles. This work was an rapid response to a small study done in North Dakota (Cornatzer et al. 2007). Grund and his team's work was originally posted at the MN DNR website in 2008 but their paper was finally published in the peer reviewed literature in 2010 (yes, peer reviewed science takes time).
Dear Dr. Grund,
A recent article in the Minneapolis Star Tribune about eagles being treated for lead poisoning at the U of M Raptor Center (Klein, 2011) inspired me to do some more reading, first on the web, and now in the academic literature. In the course of my research I found your paper (Grund et al. 2010). As a sport hunter and a regular consumer of venison I found it very interesting. I am also a graduate student at Saint Mary's University of Minnesota where my study of leadership and problem solving has led me to examine the nature of strongly held belief and its consequences.
The Star Tribune article has led to a heated discussion on the rec.guns usenet group. I'd like to think of myself as a responsible hunter and a critical thinker, so I'm embarrassed by the amount of denialism being heaped by laypersons upon the scientific data. In the minds of "lead poisoning denialists" it is obvious to that every attempt to limit human introduction of lead into the environment during hunting and fishing is simply a thinly veiled attempt to ban hunting or firearms - therefore they can discredit the data, minimize its importance, or ignore it altogether. While I suppose anti-hunting and anti-gun groups are happy for any bump in our road I don't subscribe to this conspiracy theory. Still, there are some hunters who are interested in learning more about the issue and may be receptive to making voluntary changes.
Your 2010 paper was oriented primarily toward assessing the risk of lead contamination of deer and deer-sized animal as applies to human consumption of venison. In that regard I have a question. Your research demonstrates that rinsing the body cavity of deer can spread lead to sites where the rifle shot did not originally deposit it. In the absence of data demonstrating any health or meat quality benefit from doing so, it is a procedure I intend to dispense with immediately. But even without rinsing fragments are sometimes found a surprising distance from the wound path. Do you suppose these are transported by the movement of the viscera while the deer expires, by manipulation during field dressing, or both? I am wondering if using disposable paper towels to wipe the body cavity distal to the point of entry and exit wounds toward the wound path might remove some of these errant fragments?
While the lead poisoning of scavengers was outside the scope of your study it occurs to me that your methodology might be modified to examine this related issue in greater detail. Given that many hunters will not voluntarily abandon conventional cup and core bullets containing lead it seems to me that "gutpiles" deserve more attention. Hunt et al. (2006) suggests that viscera can contain a large quantity of lead bullet fragments. This make good sense as the destruction of internal organs by expanding bullets and their fragments is a significant element of the killing mechanism, except in the case of CNS hits.
It seems to me that radiographs of viscera removed during field dressing of deer shot with the eight bullet types tested in your study (though it seems a waste of time, money, and sheep to look for lead fragments in animals shot with copper bullets) would help determine whether scavenger access to lead fragments might be reduced by the voluntary removal of offal from the field and its subsequent sequestration.
Likewise, radiographs of boned deer carcasses and discarded trim might demonstrate that it is better to bury these leftovers instead of tossing them into the woods behind the barn.
Finally, is there any literature you can refer me to that will help demonstrate the neutrality or biases of wildlife biologists engaged in the study of lead poisoning?
I appreciate your taking the time to read this long email from a layperson. My interest is genuine and based on a deep appreciation for the natural world and our place in it, both as hunters and as responsible citizens. If you become aware of any way in which a volunteer might help further a reasoned response to this issue I look forward to hearing from you.
References
Grund, M., Cornicelli, L., Carson, L., and Butler, E., (2010). Bullet fragmentation and lead deposition in white-tailed deer and domestic sheep. Human Wildlife Interactions 4(2):257–265, Fall 2010 retrieved from http://www.berrymaninstitute.org/journal/fall2010/fall2010_grund_etal.pdf
Hunt, W., Burnham, W., Parish, C., Burnham, K. Mutch, B., and Oaks, J. (2006). Bullet fragments in deer remains: implications for lead exposure in avian scavengers. Wildlife Society Bulletin 34(1): 167-170 retrieved from http://www.peregrinefund.org/pdfs/ResearchLibrary/Fragmentation%20data%20and%20radiographs.pdf
Klein, B. (2011) Enraptured at the U. Minneapolis Star Tribune February 2, 2011 retrieved from http://www.startribune.com/sports/outdoors/115062634.html?elr=KArksUUUoDEy3LGDiO7aiU
[Note: the link from the Star Tribune article to the University of Minnesota Raptor Center is broken. Click here for the connection.]
Other Resources
Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans
Lead Bullet Risks - Wildlife and Humans
A Global Update of Lead Poisoning in Terrestrial Birds from Ammunition Sources
Qualitative and Quantitative Detection of Lead Bullet Fragments in Random Venison Packages Donated to the Community Action Food Centers of North Dakota
Non-Lead Rifle Ammunition
Evidence demonstrating the problem is overstated or the result of anti-hunting and anti-gun conspiracies...let me know.
UPDATED TO ADD:
Here's a statement from the National Shooting Sports Foundation about the hazards of lead in firearms ammunition. Their bias is clearly stated in the opening paragraph.
Lead or Traditional Ammunition
The NSSF is fond of referring to the 2008 CDC North Dakota study which they say proves lead in wild game is not a health hazard. If you read the study carefully you'll note that it suggests that consumption of wild game shot with lead projectiles accounts for as much as a third of the tested North Dakota residents' subclinical blood lead levels.
