In terms of how “toxic” is defined under the act, I believe it's section 5. We need to revisit that bit about it “entering or may enter the environment in a quantity or concentration”, or under conditions that may have long-term and harmful effects.
We need to revisit that question of it “entering or may enter the environment” and put more emphasis on the inherent properties of the substance. Listing a substance on schedule 1 has many barriers. It's often a very cautious process.
You can look at it two ways. I've complained that risk management needs to be tighter and stricter and we need more enthusiastic bans to eliminate certain chemicals from the marketplace. But, as we see, because that process of risk management is so cautious, if we were to expand the definition of toxic and expand risk management, we wouldn't suddenly see thousands of substances being unuseable in an appropriate manner.