I'd think that percentage-wise, industry would be much bigger polluters.
According to this article on 'plasticizers' in effluent, there is a broad sprectrum of sources, but their focus is
on industry:
http://www.chinapost.com.tw/taiwan-business/2011/06/18/306660/EPA-to.htmEPA to tighten wastewater disposal rulesIn an attempt to prevent the contamination of the country's underground water by toxic plasticizers, the Environmental Protection Administration (EPA) will announce stricter standards to regulate the disposal of wastewater by the petrochemical industry, chip makers and semiconductor manufacturers.
The new standards, still being drafted, will provide for stricter limits on the presence of ammonia, nitrogen, six volatile organic compounds, and six plasticizers — DMP, DBP, DEHP, BBP, DEP, DNOP — in the drainage systems of such plants. Even stricter control over the disposal by the chipset and semiconductor industries will be enforced, targeting toxic organic substances in general.
A total of eight plasticizers, including the six mentioned above as well as DIDP and DINP, were reclassified as Class I and Class II toxins in early June, but DIDP and DINP are not incorporated in the new standards that will soon be announced because their use is quite limited in the country.
The other chemicals are not covered by current standards because the substances can dissipate on their own and sewage processing plants can eliminate 90 percent of the plasticizers. However, the EPA has decided to incorporate these chemicals and the six plasticizers into the new standards anyway.
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According to other EPA officials, plasticizers have been detected in the mud at river basins, and their sources could be either industrial wastewater or wastewater from ordinary households. Illegal disposal of waste and illegal garbage dumping can also be blamed, the officials added...cont'd
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I'm assuming that "micro-plastics" (so named in the OP article) and "plasticizers" named in the article I'm posting here, are one in
the same.