But it is one thing: undeniably objective. The alternative would include a "rating" system which the industry can use to say "yeah we emit x hundred tons per year of chemical y but it is next to harmless, better go after company z and their waste"... leading to inevitable chains of lawsuits dragged over years.
For what its worth for many industrial processes there exist technical means of greatly reducing emissions (e.g. for smoke stacks: gas washers, desulfurization technologies, fine-dust retainers), but as long as environmental costs don't get billed to companies or required by the state, companies have no incentive to reduce emissions, as every dollar spent is a dollar less profit.
Maybe it's time to introduce legislations that allow the government to hold the shareholders accountable e.g. for Superfund sites, that would at least provide a decent incentive for companies to clean up or to provide enough cash to compensate for environmental damages after closure - right now companies can simply close/be liquidated and the taxpayers have to foot the cleanup bill.
Not to mention that much of the stuff that gets released in huge quantities can actually be used as a natural resource. Instead of capturing and using it we're throwing all the stuff away.
Therefore, any way of looking at the environmental issues is good - anything that can be tackled should be tackled.
Let an actual free and fair market solve it. When externalities have to be included in pricings (be it insurance premiums for superfund cleanup, earmarked money in trusts for cleanup, or simply preventing emissions in the first place) instead of having them shouldered by society, the market will by itself weed out companies doing excessive environmental damage.
Ideally, yes, but that's like saying "we'll just use nuclear fusion to meet our energy needs."
Do you have any data to support this fairytale?
If I have 10kg of mercury and I dump it in a river, that measures 10kg of toxic waste.
But if I have pile of 10 million kg of rock that contains 1kg of mercury, it's reported as a million times worse for 1 tenth the toxin.
Less toxic stuff will have a lower rating per pound, while more toxic stuff would kill more people per unit of weight.
Copper and manganese are on the list, and are absolutely necessary to live! If you completely cut them out, you would die.
Although numerous studies with rats, hamsters, minipigs, goats and chicks have indicated that arsenic is an essential nutrient, the physiological role of arsenic is open to conjecture. Recent studies have suggested that arsenic has a physiological role that affects the formation of various metabolites of methionine metabolism including taurine and the polyamines. The concentration of plasma taurine is decreased in arsenic-deprived rats and hamsters. The hepatic concentration of polyamines and the specific activity of an enzyme necessary for the synthesis of spermidine and spermine, S-adenosylmethionine decarboxylase, are also decreased in arsenic-deprived rats. Thus, evidence has been obtained which indicates that arsenic is of physiological importance, especially when methionine metabolism is stressed (e.g. pregnancy, lactation, methionine deficiency, vitamin B6 deprivation). Any possible nutritional requirement by humans can be estimated only by using data from animal studies. The arsenic requirement for growing chicks and rats has been suggested to be near 25 ng g(-1) diet. Thus, a possible human requirement is 12 μg day(-1). The reported arsenic content of diets from various parts of the world indicates that the average intake of arsenic is in the range of 12-40 μg. Fish, grain and cereal products contribute most arsenic to the diet. - https://www.ncbi.nlm.nih.gov/pubmed/24197927
To compare the states properly they would need to do a risk assessment essentially, which is difficult and complex to say the least...
Also most of the 'toxins'from mining are probably heavy metals which are pretty easy to treat and contain in that context.