Zero VOC does not mean non toxic. Volatile Organic Compounds are ingredients in paint that evaporate and are deemed to be detrimental to the environment, mostly concerning air quality and ozone health., but you don't want to drink it or breath the over spray from spray rigs because it can be very toxic.
Most of Today's exterior paints have lowered the VOC content to meet Federal and local regulations. I would not chance using a niche brand, use a high quality name brand acrylic latex paint.
Best Luck,
rmichael