Answer: Citrus foliage is not poisonous, nor are the flowers. However, any plant part has the potential to cause distress if ingested by a person sensitive to it, or in great quantities, for example. For your future reference, Monrovia's website can be searched with the attributes Foliage Poisonous and Fruit Poisonous and here are websites that list poisonous plants.
http://www.ansci.cornell.edu/plants/index.html from Cornell University.
Poisonous plants in Canada (many grow here as well) http://res.agr.ca/brd/poisonpl/
Q&A Library Searching Tips