Chemical contaminants present in foods are often unaffected by thermal processing (unlike most microbiological agents). Chemical contaminants can be classified according to the source of contamination and the mechanism by which they enter the food product.nvironmental contaminants are chemicals that are present in the environment in which the food is grown, harvested, transported, stored, packaged, processed, and consumed. The physical contact of the food with its environment results in its contamination. Possible sources of contamination include:
For the record,  cfprefsd is a fundamental part of the MacOS operating system. It's a tool developers use when they write their application, and allows an application to read/write/modify preferences files (like files ending in .plist, and others).
PPD files are System Files primarily associated with PhotoImpression Project (ArcSoft Inc.). PPD files are also associated with PostScript Printer Description, PageMaker PostScript Printer Description (Adobe Systems Incorporated) and FileViewPro. Additional types of files may also be using the PPD file extension.