One EU is approximately equivalent to 100 pg of E. coli lipopolysaccharide—the amount present in approximately 105 bacteria. Humans can develop symptoms when exposed to as little as 5 EU/kg body weight. These symptoms include, but are not limited to, fever, low blood pressure, increased heart rate, and low urine output. Even small doses of endotoxin in the blood stream are often fatal.
The FDA has set the following maximum permissible endotoxin levels for drugs distributed in the United States:
Drug (injectable, intrathecal) - 0.2 EU/kg body weight
Drug (injectable, non-intrathecal) - 5 EU/kg body weight
Sterile water - 0.25-0.5 EU/ml (depends on intended use)