I think the lead worry came up after watching the new Cosmos series - which my kids enjoyed a lot, but there was that one episode about lead poisoning - she must have taken it to heart.
I think at this age they are perhaps starting to be more exposed to (and paying attention to) news, current events and so on. Also, DD's school had a 'health' unit about the dangers of drugs and alcohol which went on for weeks and really upset her. I tried to have a glass of wine with dinner one day and that caused a panic attack!
But with DD we started noticing small amounts of anxiety around age 8. It's increased over time - at the beginning we had no idea what was happening or how to deal with it.
