Valid, or fallacious?

Thank you very much for your thoughtful response.

Few things. First, this looks like it is a deductive argument but it is not.

A deductive argument is an argument that is intended by the arguer to be (deductively) valid, that is, to provide a guarantee of the truth of the conclusion provided that the argument's premises (assumptions) are true.

We would need to add the premise "anything that causes harm (or death) is hazardous" (i.e., Old age causes death, but is not hazardous. People have also died from sneezing and other things are are not considered hazardous). Without that, this is not a deductive argument, therefore, by "valid" we can mean "reasonable" rather than what it means in a deductive sense.

So is it reasonable to say that because something could cause harm and death that it is hazardous? Not by those two conditions alone. There are too many things that fit those categories that are not considered hazardous by any reasonable person. Maybe if "frequently" were added (i.e. electricity frequently causes harm to people) then it would be more reasonable.

It is definitely not circular because because as we have seen, "harm" and "death" are not the same as "hazardous".

So for the fun of it, let's make an deductive argument out of this.

P1. Electricity frequently causes premature death.
P2. Anything that frequently causes premature death is hazardous.
C. Therefore, electricity is hazardous.

If both premises are true, the conclusion MUST be true. Note that I added "premature" to get around the "old age" argument :) Also note that one can still argue that one or both premises are not true.