Boys and girls are going through puberty much earlier than what's normal, researchers say.

In a finding that can have all sorts of negative health ramifications, researchers from the University of North Carolina have discovered that boys are now going through puberty up to two years earlier than boys did 30 years ago.

African-American boys are entering puberty at about 9 years old, while white and Hispanic boys entered puberty at about age 10—both much earlier than what is considered normal.

Since there hasn't been a lot of research investigating the change in puberty age—or what's causing it—researchers are hypothesizing that exposure to chemicals, nutrition, obesity, and epigenetics (inherited changes in gene expression) could all be at play. This study IDs the need for further investigations into the causes of early puberty.

"Just because the 'average' age of puberty for boys seems to be 9 or 10, depending on race, that doesn't mean these early changes are 'normal,' in the sense of being healthy," explains lead study author Marcia Herman-Giddens, DrPH, professor of maternal and child health at University of North Carolina. Her study was published in the journal Pediatrics.

Of immediate concern is that young males' physical traits are outpacing brain development. "What concerns me most about these findings is the gap between the onset of physical development in boys and the maturity of the brain," explains Herman-Giddens. "So you have boys developing sexually very early, yet they are in no way equipped to deal with any of the issues related to the issues that come with it; and the gap keeps getting bigger."

Earlier puberty can affect health decades down the line, too. Premature puberty may predict future health and increase the risk of metabolic syndrome, obesity, type 2 diabetes, and cardiovascular disease later in adulthood. Some—but not all—studies looking at early puberty and cancer risk have found an increased risk of testicular cancer.

These findings jive with earlier research showing girls are going through puberty much earlier, too, which can impact body image and increase the risk of breast cancer decades later. Certain chemicals, including plastics chemicals and dichlorobenzene, a solvent used in mothballs, toilet bowl cleaners, and air fresheners, have been linked to early puberty in girls.

While exposure to environmental chemicals—particularly a combination of hormone-disrupting chemicals found in many everyday products—could be to blame, researchers say much more research is needed.

In the meantime, experts suggest parenting resources should reflect the change in puberty to inform parents to talk about sex earlier in life. To create a safer household, read 12 Household Toxins to Banish from Your Home.