Level 1 hazardous materials would cause irritation on contact but only mild residual injury, even without treatment.
The risk levels are rating from four to zero, highest risk to minimum risk.
Materials are too dangerous at level 4.
Materials extremely hazardous to health at level 3.
Materials hazardous to health at level 2.
Materials are only slightly hazardous to level 1.
Materials are not hazardous to health at level 0.