Sadly, the UVT article is exactly the kind of pseudo-scientific publication that annoys the snot outta me. Yes, the study contained toxicology statistics, because they are easy to quote and relatively uncontroversial. It also contained data of how many loons found dead had lead objects in them; a very powerful number if viewed non-critically.
However, the article failed to cover the really key statistic - the per-capita deaths of the loon population due to lead pellet ingestion. If 22% of 200 loons (44 actual count) found dead were killed via lead pellet ingestion out of a watershed population of 2000, we might rightly conclude that our activities are causing serious harm to this species and that restrictive regulation was needed. However, if 22% of 202 loons (44 actual count) found dead were killed via lead pellet ingestion out of a watershed population of 200,000, then we might alternatively conclude that our ecological footprint is small enough to not warrant further regulative action. The article also failed to indicate if the loon deaths due to lead ingestion were having a negative impact upon the population stability in the study regions (i.e. they're being killed faster than they can reproduce), and failed to address whether or not lead ingestion is a principal factor in loon death or if other factors are more statistically significant than lead ingestion (e.g. upstream run-off of nitrates or phosphorus compounds caused more loss of habitat and population compression than ingestion of lead sinkers).
If we're going to talk about an issue as if it's systemic relative to a species or ecosystem, then the data used to analyze the issue should address the totality of the ecosystem.
Passing regulation based upon incomplete data, simply because it sounds plausible, is a fraud.
Lead sinks in water. So are these birds eating off the bottom of ponds?
Yes - waterfowl collect sand and pebbles in their crop to grind up the vegetation that they consume, and they will hoover up the smooth lead shot pellets from the bottom to add to their crop. Unlike lead ingested by other animals, these lead pellets will not pass thru the bird with relatively little harm, but will instead sit in the crop and release lead into the bird's digestive tract until the bird is poisoned.