"Unintentional injuries—such as those caused by burns, drowning, falls, poisoning and road traffic—are the leading cause of morbidity and mortality among children in the United States. Each year, among those 0 to 19 years of age, more than 12,000 people die from unintentional injuries and more than 9.2 million are treated in emergency departments for nonfatal injuries."
http://www.cdc.gov/safechild/child_injury_data.html
Perhaps only a handful of them occur at a zoo, as a result of an interaction with an animal. But if people are seriously going to accuse this woman in particular of gross negligence and she should be investigated by child services, then there are 9.2 million other people, at least, every year who should also be investigated. That might take a while though.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix