Measurements

µg/L (microgram per litre), equivalent to parts per billion (ppb)
ng/mL (nanogram per millilitre), equivalent to parts per billion (ppb)
µg/g (microgram per gram), equivalent to parts per million (ppm)
ng/g (nanograms of the chemical per gram sampled tissue), equivalent to parts per billion (ppb)
cre= creatinin, in urine measurement
µmol/L (micromoles per litre)
nmol/L (nanomoles per litre)