Hi,
try the following link: http://www.bioshieldpaint.com
I did a lot of research on the net some time ago when I needed to paint my son's table and chairs. Not sure if they have paint for exterior as well, but if you want something really non toxic this is a place I would go. It might be a little bit pricey but worth it.
Good luck.

Benjamin Moore has a low odor paint which I believe is less toxic though probably not pure. When we built our house we painted with an alternative non-toxic paint. I tell you the stuff smelled strong and the smell lasted far longer than conventional paint. It really bothered me.

My folks just painted with Benjamin Moore low odor and I could barely smell it. If they hadn't mentioned they had painted I wouldn't have known by the smell. Here's a brief article I found:

http://paintpro.net/Abstracts/PP605_LowVOC.cfm

http://www.successfulhealing.com