American girls are now reaching puberty as young as SIX in phenomenon scientists think may be linked to childhood obesity, chemicals in plastic and stress

Young girls in America are experiencing puberty at an earlier age than biologists would particularly expect with the average age falling to ten, with black girls undergoing the process a year earlier than their peers on average, experts warn.

The phenomena was first detected by Dr Marcia Herman-Giddens, a public health expert at the University of North Carolina, when she began to gather data on more than 17,000 girls in the mid-1990s.

She found that the average age of puberty was dropping, falling to ten years old, with some girls developing as early as age six. 

https://www.dailymail.co.uk/health/article-10834835/Young-girls-starting-undergo-puberty-young-six-years-old.html