第三是环境因素。在青春期提前的讨论中，环境化学因素是最被经常讨论的一点。然而，与前两类因素相比，内分泌干扰物在人群层面的证据最为复杂，也最具争议。
Flanagan et al. 1993, many modern compilers
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This doesn't necessarily mean it will gain approval to operate the reactor, but it's a critical step for the company.
hfp=9, hsync=16, hbp=18: horizontal front porch, sync pulse, and back porch (total line = 320+9+16+18 = 363 pixels)