toxicity tests find out safe level
NOEL – No Observe Effect Level
Highest conc. that have not toxicity
LOEL– Lowest Observable Effect Level
Lowest test concentration that have toxicity
MATC – Maximum Allowable Toxicant Concentration
Geometric mean of NOEC and LOEC
Often called the “chronic value”
Allowable level
Time weight average: TWA
Fine the highest dose that human can expose safely in long time