Puberty. I don't know about you, but I'm just glad I survived it.
Puberty is a subject that has captivated researchers for the past decade or two. Why? Scientists have noticed many changes in the age of onset of puberty and have come to realize that it is a sign of the toxic chemical and hormonal onslaught that has become a part of modern life.
If you've spent any time on this site, you know that we are drowning in a flood of xenoestrogens, everything from Bisphenol-A, Phthalates, PCB's, pesticides, livestock hormones - the list goes on and on. One of the ways this tidal wave manifests itself is during puberty. Researchers have noted, for example, that females are going through puberty and breast development much earlier than in the past.  For example, one European study found that European girls now go through breast development a year earlier on average.  A NY-based study found similar results: a higher percentage of girls were going through early breast development when compare with either 10 or 30 years ago. 
One of the reasons that this is occurring, according to an ever-growing body of research, is the greater estrogen load placed on our young women leading to accelerated puberty and its onset. What about boys? In boys, the xenoestrogens have the opposite and arguably more devastating effects. Let me quote from one study: "In boys, exposure to PCBs, PCDFs or the pesticide endosulfan was associated with delayed puberty or decreased penile length."  The problem is so serious that it can actually lead to a smaller penis. Oy vay!
Polybrominated biphenyls, very toxic compounds used as a fire retardants, have also been associated with delayed puberty.  And the damage extends to fertility and reproduction: one study of maternal beef consumption found that the hormones in beef altered fertility later in life for their male children. 
Dozens and dozens of animal studies clearly show that exposure to these chemicals can easily lead to pubertal, sexual, gonadal and reproductive issues later in life. Now human research is finding, of course, that the same issue exists in humans as well. We are literally forever altering our children and their future. Furthermore, some of you may be wondering where your fertility and hormones went and this inundation of environmental estrogens may help explain much or all of it.
And lest you think that this only applies to those exposed to massive doses, one recent study cautions that estradiol (one of the human estrogens) has been grossly overestimated in kids.  This same study ominously warns that "children are extremely sensitive to estradiol and may respond with increased growth and/or breast development even at serum levels below the current detection limits [and] changes in hormone levels during fetal and prepubertal development may have severe effects in adult life."
We simply have no idea what we've been doing to our kids and, for that matter, to ourselves. You've got to watch out for the little guys - they can't defend themselves after all. I urge all parents to do as much as possible to help your kids avoid Excitotoxins, Bisphenol-A, pesticides, plastics, canned goods and other common sources of xenoestrogens. Give them the chance that you may never have had.
1) International Journal of Andrology, Apr 2010, 33(2):346-359, "Hypothesis: exposure to endocrine-disrupting chemicals may interfere with timing of puberty"
2) Pediatrics, 2010, "Pubertal Assessment method and baseline charactersitics in a mixed logitudinal study of girls".
3) International Journal of Andrology, Feb 2006, 29(1):264-271, "Endocrine disrupters and human puberty"
4) Molecular and Cellular Endocrinology, Aug 2010, 234(1-2):39-44, "Trends in puberty timing in humans and environmental modifers"
5) Pediatrics, 2009 May, 123(5):e932-9, "Recent decline in age at breast development: the Copenhagen Puberty Study"
6) Hum. Reprod, published online on March 28, 2007, "Semen quality of fertile US males in relation to their mothers' beef consumption during pregnancy"
7) Human Reproduction Update, 2006, 12(4):341-349, "The sensitivity of the child to sex steroids: possible impact of exogenous estrogens"