Lowest Observed Adverse Effect Level

Similar term(s): LOAEL, LOAL (lowest observed effect level).

The lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects on people or animals.

Source: ATSDR glossary 

Can apply to a particular study, species (e.g. rat, dog), or all studies on a particular substance. The difference between LOAEL and LOEL rests on the definition of adverse effect only, that is, an experimental study that produced a LOAEL will have stated the adverse effect to be observed before initiation.

PCBs

Water Disinfectants

Dioxins