The Devcon Corporation is a large manufacturer of epoxy. In its MSDS, Devcon stated that epoxy and its hardener are toxic to marine life. In laymen's terms, the chemicals are poisonous to fish. This relates to uncured epoxy. Cured epoxy forms a hard plastic. The Entropy Resins Corporation states the cured hard epoxy is nonhazardous.
The uncured epoxy chemicals slowly seep into the ground, eventually reaching the water table. Once in the table it disperses causing contamination, according to the United States Fish and Wildlife Service (USFWS). This is a common trait of many liquid contaminants spilled onto the ground. Solid cured epoxy spilled on the ground is like a hard plastic, which can be cleaned up and disposed of properly.
When in liquid form, the spilled chemicals are carried by water currents and drift into other water areas. This is akin to an oil spill, which is carried around by currents. The Devcon Corporation points out the effects are adverse and long term.
The USFWS notes that cumulative effects may take place. Epoxy chemicals may mix with other spilled chemicals, forming new toxic substances. This scenario can happen quite easily on a construction site. For example, a bucket of epoxy hardener may be next to a can of acetone, and a backhoe hits the two. As of 2011, research is ongoing into cumulative effects on water.