Vinylidene chloride (1,1-Dichloroethylene)

Vinylidene chloride (1,1-DCE) was the monomer used to make polyvinylidene chloride (PVDC) — commercialized by Dow Chemical in 1939 as Saran Wrap [1]. It found enormous consumer use as a food wrapping and preservation product. But its most significant environmental presence today is not from direct production — it is a degradation product of chlorinated solvents. When TCE, PCE, or 1,1,1-trichloroethane break down in groundwater through a natural process called reductive dechlorination, they pass through a series of degradation products that include 1,1-DCE and vinyl chloride [2]. This means communities with groundwater contaminated by dry cleaning solvent spills or industrial degreaser releases often face a mixture of the original solvents plus their degradation products — including the highly toxic vinyl chloride and vinylidene chloride. Understanding this degradation pathway is essential for risk assessment at contaminated sites [3].

Contaminated groundwater near sites where chlorinated solvents have been released — dry cleaners, aircraft maintenance facilities, electronics manufacturers, and military bases — is the primary exposure pathway [1]. Vapor intrusion is a secondary route: vinylidene chloride is volatile and migrates through soil gas into building basements and crawl spaces. Past food packaging exposure from PVDC cling wrap was likely very low [2]. Occupational exposure in vinylidene chloride monomer production and in food packaging manufacturing involves inhalation of the monomer vapor [3].

Vinylidene chloride is classified as a possible human carcinogen (IARC Group 2B), with animal evidence for kidney, mammary gland, and lung tumors [1]. It is metabolized to reactive epoxides that damage DNA, and it can deplete glutathione antioxidant defenses in liver and kidney cells. The acute effects at high concentrations include CNS depression (dizziness, headache, unconsciousness) and cardiac sensitization to arrhythmias [2]. As a groundwater contaminant that is both toxic and a precursor to the even more toxic vinyl chloride, 1,1-DCE complicates risk assessment and remediation at chlorinated solvent sites [3].

People who live above or near TCE/PCE groundwater contamination plumes — particularly above old dry cleaning sites — face both the original solvents and their degradation products including vinylidene chloride [1]. Workers in vinylidene chloride monomer production and polymerization facilities face occupational inhalation exposure [2]. Residents of communities where vapor intrusion from chlorinated solvent plumes is documented should have indoor air tested for the full suite of chlorinated volatile organic compounds, not just the original solvent [3].

Use a certified carbon block or reverse osmosis filter for drinking water if you live near chlorinated solvent contamination [1]. Request indoor air testing if you live above a documented TCE, PCE, or TCA groundwater plume — a standard VOC panel will detect vinylidene chloride as well as other degradation products [2]. When evaluating real estate near former dry cleaners or industrial facilities, request environmental site assessment reports and look for the full suite of chlorinated VOCs including degradation products [3].