The substances that our company uses do not leave stains, do not have an unpleasant smell and are not toxic.
The substance used by the company will not harm people if they accidentally inhale some fumes from it.
By definition, being non-toxic means that, in reasonable quantities, the fumes will not damage the human respiratory system. I think the language used was too different from the context and the system wasn't able to parse meaning. 
( z1 harm :polarity - :ARG0 ( z2 substance :ARG1-of ( z3 use :ARG0 ( z4 company ) ) ) :ARG1 ( z5 person ) :condition ( z6 inhale :ARG0 z5 :ARG1 ( z7 fume :quant ( z8 some ) :source z2 ) :manner ( z9 accidental ) ) )