Reference values for environmental pollutants in the German population are established continuously by the Human Biomonitoring Commission of the German Federal Environment Agency. The reference value for 1-hydroxypyrene in urine was derived from the representative adult population data collection of the 1998 German Environmental Survey (GerES III) and the representative data collection for children of the German Environmental Survey on Children, 2003/06 (GerES IV). For the non-smoking general population (aged 3-69 years) the commission derived a reference value of 0.5 microg/l (corresponding to 0.3 microg/g creatinine) for 1-hydroxypyrene in urine. For 1- and 2-naphthol levels in urine the amount of data is small and not representative of the German population. Therefore, the commission recommends the following upper margins of background exposures for adult non-smokers: 1-naphthol less than 30 microg/l, 2-naphthol less than 20 microg/l.