"There's something rather odd about discussing the toxicity of a bullet"
I guess that comes from not being allowed to own guns and shoot.
Lets talk about shotguns. Lead Shot vs Steel Shot.
Which shot would you rather have in your game bird?
In Chicago, there once was a trap range where they flung the targets over the lake.
They phased out lead shot because of its polluting the environment.
Or that deer?
There were a lot of rumors swirling around about the shortage of .22lr ammo.
Seems that they increased the weight (amount of lead) due to EPA regulations. Ironically they increased the amount of lead (weight) in the rounds.
The point is that beyond military applications, you have sport shooters and range time where you will expend more ammo than during a military conflict. That's where you want to keep your environment healthy.
But back to the article...
Steel core bullets aren't new. Most ranges will not let you shoot with steel in them because they cause more damage to the indoor retaining walls and materials. Some outdoor ranges won't allow it because steel core / tipped rounds may cause sparks and fires.
A larger issue with non military rounds is controlled expansion. When you hunt, you want to kill the animal as quickly as possible.