Ah, government regulation. The bottom of my D5100 has seven government or industry-mandated symbols on it. The one you refer to is a 10 with two arrows circling it. This has little to do with disposing of the equipment. It fulfills a Chinese government RoHS regulation. RoHS is short for Restriction of Hazardous Substances. It appears on items that have lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers. The 10 refers to the number of years before any of these substances is likely to leak out and cause harm to health or the environment (I believe 10 is the maximum value you can put there even if you're confident that it'll take longer).
Hmm, now I suspect that we'll have a fire sale on D5100's nine years from now. And you thought the EPA was watching out for you.