Expert: George Maxwell - 2/9/2008

Question
Hi:

How do powerful reducing agents injure human skin? I know that a reducing agent will donate electrons. What affect would the strongest reduction agent have on the human skin?

If a reducing agent accidently splashes into a subject's cornea, what are the chances of his/her vision recovering?

Is a reducing agent stronger than an oxidant of the same strength?


Thanks,

Green

Answer
Hi, and thanks for your question.

You're quite right that reducing agents donate electrons, and oxidizing agents accept them, in order to carry out respectively oxidation and reduction.

In actual fact, as a general rule, reducing agents are less damaging than oxidizing agents: the carbon, phosphate and similar base elements that make up human skin are often in a fairly reduced state already - it is easy to oxidize them, but harder to reduce them.

That is not to say that very strong reducing agents cannot cause damage, but this is often a physical process - the reaction of the reducing agent with moisture on the skin can be so exothermic that it causes thermal burns. Additionally, the components of commercial reducing agents can be hazardous in themselves (acidic, basic etc), and this will often be more important in terms of health risks.

For this reason, it's impossible to say how damaging eye contact with a generic reducing agent will be. I would guess that, purely in terms of electron transfer, oxidation of the cornea would be a greater risk than reduction, but because of the possibility of physical reactions or acidic / basic strength of the reagent, this is a theoretical, rather than a practical conclusion.

In general, alkalis are more dangerous in the eye than acids because of their tendency to hydrolyse organic matter, and because they form soaps with human tissue, resisting efforts to wash them out.

Because of these complications, the oxidizing / reducing strength of a material won't often be a good guide to its health effects. I can splash sodium chlorate solution over my skin with only mild irritation despite the fact that sodium chlorate is so powerful an oxidizer that it is used in the manufacture of explosives. A milder oxidizing agent, household bleach, will be far more damaging to my skin, and far more dangerous to the eyes (because it contains sodium hydroxide).

In summary, reduction and oxidation are primarily concepts important to the chemist, and it will be other characteristics of reducing compounds that generally produce significant health hazards.

Hope this helps.