I was reading the forum at Dreamstime and came across this one...
http://www.dreamstime.com/thread_10701

I was wondering what everyone does over here.  If you shoot a child, do you put their age as a keyword?  If you do, do you put "ten" or "10"?  And finally, do you think any agencies would reject a picture for this keyword(s) for incorrect or unneeded keywords?

Thanks for your thoughts.

i sometimes put the age down, but as was mentioned in the dreamstime thread, it is tough because ages are so vague. 

If I do put an age though, i would put " 20, twenty"

Some designers must find it useful, because one asked for it in the dreamstime thread, and in the istock keywords they have tickboxes for the age if you put it in as a keyword.

It really would be nice if there were some kind of standard.  I don't do very many people shots -- yet -- but when I do I usually enter 20s, or 50s, or 60s, indicating the decade.  But, should it be just 20, or 20s, or 20's?  Seems as though I've seen 50-60 instead of 50s.

After researching ages on sites like Getty and Corbis, I decided to use both -- 20s and 20-30.  With children, I provide the specific age because they change so rapidly.  If I don't know the model's age, I will add a two age ranges like 50-60 and 60-70 with 50s and 60s.     

I think it was Photoshelter's School of Stock (but I am not sure) that specifically advised to putting the age in the keywords.  I do it with kids as precisely as possible (although it might be misleading even there, some 4 year olds look like they are 6, other more like 3) and for adults I write twenty, 20, 20s, twentysomething or 40, 40s, fortyish - although at least Shutterstock is not happy with the last option and constantly throws it back as a typo.

becomes a pain with some shots, my youngest is adamant she is not 8, "I'M EIGHT AND THREE QUARTERS"