Most commonly, outbreaks of puberty in children are traced to accidental drug exposures from products that are used incorrectly.
Dr. Dedekian’s first patient was evaluated for possible genetic endocrine problems and a rare brain tumor before the cause of her puberty was discovered. It turned out that her testosterone level was almost 100 times normal, in the range of an adult man. The same problem affected her brother.
The doctors realized that the girl’s father was using a concentrated testosterone skin cream bought from an Internet compounding pharmacy for cosmetic and sexual performance purposes. From normal skin contact with their father, the children absorbed the testosterone, which caused pubic hair growth and genital enlargement. The boy, in particular, also developed some aggressive behavior problems.
...At that time, unregulated “prohormones” like Andro, famously used by Mark McGwire, the former St. Louis Cardinals power hitter, and banned by federal law in 2005, were available as topical sprays used to enhance libido. Dr. Jones said the sprays used by adults in some households permeated the children’s bedsheets, and the early puberty stopped only when the adults stopped using the sprays and also discarded old sheets.
http://www.nytimes.com/2006/10/17/science/17puberty.html?em&ex=1161403200&en=f756136b60c9b213&ei=5087%0AOther problems from "estrogen contamination of beef and poultry", “endocrine disruptors”, "shampoos that contained estrogen and placental extract", " food contaminated by a flame retardant, PBB", "a plasticizer called phthalate", & lavender and tea tree oils ("had the same effect on the cells as estrogen").