The Three-Minute Outdoorsman: Wild Science from Magnetic Deer to Mumbling Carp

17. Lead, Lead, Everywhere?

I N T H E W O O D S 75 17 lead, lead, everywhere? What is a common denominator in the following human physiological problems? • impaired motor function • impaired cognitive ability • reduced intellectual development • impaired kidney function • reduced endocrine function • impaired tissue growth • impaired reproductive development • spontaneous abortion • decreased brain volume • behavioral abnormalities No, they are not characteristics of your in-laws, as relevant as the last two might seem. If you answered lead in our bodies, you would be right (or you read the title of the chapter). This laundry list of human maladies caused by lead makes clear why we are now so aware of getting the lead out of our environment. Not to mention not inhaling it at the gas pumps anymore. It’s really toxic stuff, and it’s not like some other things in our environment that are beneficial in small amounts. As far as we know, lead has no biological role. However, a handy online calculator tells us that the average two-hundredpound person has approximately 0.15 grams (0.005 ounces) of lead in their bodies, so we ingest or inhale it nonetheless. And remember earlier writers’ assertions that the form of lead in bullets would prevent human contamination? Although it is true to a degree, lead bullets that have been fired from a gun likely do provide a source of lead contamination. Of course, given we absorb lead from other sources, it is difficult to determine whether such exposure by itself would lead to levels that exceed the Centers for t h e t h r e e - m i n u t e o u t d o o r s m a n 76 Disease Control exposure level threshold. But no matter, I think I’d prefer not to add any new sources of lead contamination to my tissues and bones. Age has caused enough problems. Lead products break down over time, and lead gets into the soil, water, and plants. Once it gets into the bloodstream, it builds up in soft tissue and comes to rest in bone. Once in bone, it can remain there for decades, where it occupies molecular positions normally occupied by calcium. The reason for this is that the chemical properties of lead mimic those of calcium. Because calcium plays a huge role in the working of our nervous system and lead does not work the same as calcium in nerve functioning, lead poisoning leads to serious neurological effects. A 2012 article by W. Grainger Hunt in the Journal of Raptor Research reviewed the toxic properties of lead in general and how they affect birds of prey. I found it a sobering lesson on the longterm effects of how we have treated our environment and can only say I’m sorry for my part in adding lead sinkers and shot to the environment. If I’d have known then what I do now, I would have acted differently. However, I recently tried to buy some nontoxic sinkers at the private bait shop on Lake Itasca in Itasca State Park only to be told that they didn’t stock them because it was legal to use lead—on a lake to which many come to see nesting loons! In the article, Hunt reported on the effects of lead ingestion on birds of prey. We have known for a long time that birds feeding on waterfowl ingested lead pellets, which were not lethal to the ducks (at least at the time they were shot) but built up in birds of prey that scavenged them. This observation led to bans on lead shot in waterfowl hunting. Despite much angst, we seem to have accepted this imposed sanction on lead shot, no doubt for the better . More recently, researchers discovered that gut piles often contain lead fragments from bullets. In one study, 90 percent of gut piles contained lead fragments, and 50 percent contained one hundred or more lead fragments. Scientists think that the reintroduced population of California condors in Arizona will not be I N T H E W O O D S 77 self-sustaining unless the birds are monitored and treated for lead poisoning, which they get by feeding on gut piles from huntershot elk and deer. Many lead-poisoned condors develop crop stasis (where food doesn’t pass through the digestive system), and they end up on the ground unable to fly...