Precursor

{
  "id": "MLC-T-ENV-021899",
  "term": "Precursor",
  "field": "Environment",
  "definition": "1. In photochemistry, a compound antecedent to a pollutant. For example, volatile organic compounds (VOCs) and nitric oxides of nitrogen react in sunlight to form ozone or other photochemical oxidants. As such, VOCs and oxides of nitrogen are precursors.\n\n2. In photochemistry, any compound antecedent to a pollutant. For example, volatile organic compounds (VOCs) and nitrogen oxides react in sunlight to form ozone or other photochemical oxidants. As such, VOCs and nitrogen oxides are precursors.\n\n3. Material that is manufactured to undergo further chemical change or processing to ultimately manufacture an active ingredient or finished dosage form of a drug. This term does not include commodity chemicals produced by the synthetic organic chemical manufacturing industry.\n\n4. Chemical substance which is not contaminated due to the process conditions under which it is manufactured, but because of its molecular structure, and under favorable process conditions, it may cause or aid the formation of HDDs/HDFs in other chemicals in which it is used as a feedstock or intermediate.",
  "subject": "General environmental",
  "references": [
    "Terms of Environment",
    "EPA Report on the Environment Glossary at http://www.epa.gov/ncea/roe/glossary.htm; Report on the Environment (ROE) Glossary",
    "40 CFR 63.1251 (CFR 2013)",
    "40 CFR 766.3 (CFR 2013)"
  ],
  "url": "https://mlchart.com/terminology/environment/precursor/"
}