Breathing high levels of 1,2-dichloroethene can make you feel nauseous, drowsy, and tired; breathing very high levels can kill you.
When animals breathed high levels of trans-1,2-dichloroethene for short or longer periods of time, their livers and lungs were damaged and the effects were more severe with longer exposure times. Animals that breathed very high levels of trans-1,2-dichloroethene had damaged hearts.
Animals that ingested extremely high doses of cis– or trans-1,2-dichloroethene died.
Lower doses of cis-1,2-dichloroethene caused effects on the blood, such as decreased numbers of red blood cells, and also effects on the liver.
The long-term (365 days or longer) human health effects after exposure to low concentrations of 1,2-dichloroethene aren’t known. One animal study suggested that an exposed fetus may not grow as quickly as one that hasn’t been exposed.
Exposure to 1,2-dichloroethene hasn’t been shown to affect fertility in people or animals.
The EPA has determined that cis-1,2-dichloroethene is not classifiable as to its human carcinogenicity.
No EPA cancer classification is available for trans-1,2-dichloroethene.
From ATSDR website