In linguistics and grammar, a pronoun (abbreviated PRO) is a word that substitutes for a noun or noun phrase. It is a particular case of a pro-form.
Some of the most significant toxic effects associated with substances used or emitted in plastic production include: 13. 1  Benzene (PET, PVC, LDPE, PP): known human carcinogen, workplace exposure depresses the nervous system. 2  Chromium oxide (HDPE, LDPE): suspected carcinogen, damaging to the liver and nervous system.ome of the most significant toxic effects associated with substances used or emitted in plastic production include: 13. 1  Benzene (PET, PVC, LDPE, PP): known human carcinogen, workplace exposure depresses the nervous system. 2  Chromium oxide (HDPE, LDPE): suspected carcinogen, damaging to the liver and nervous system.
Trace amounts of benzene may result whenever carbon-rich materials undergo incomplete combustion. It is produced in volcanoes and forest fires, and is also a component of cigarette smoke. Up until World War II, benzene was produced mainly as a byproduct of coke production in the steel industry. In the 1950s, however, as the demand for benzene increased, especially from the growing plastics industry, necessitating its production from petroleum.