Richtwerte für die Innenraumluft: erste Fortschreibung des Basisschemas

Abstract

In order to harmonize recommendations on the evaluation of indoor air contamination by means of guide values, the Ad-hoc Working Group of the Indoor Air Hygiene Commission of the German Federal Environment Agency and of the Supreme State Health Authorities (IRK / AOLG Ad-hoc working group) has updated the procedures for toxicologically derived indoor air guide values for individual substances or groups of substances. In general two guide values are proposed by the committee. Guide value II (RW II) is an adverse effect-related value, based on current toxicological and epidemiological knowledge of a substance's effect threshold, usually the LOAEC or a benchmark concentration from human or animal studies. Guide value I (RW I) represents the concentration of a substance in indoor air for which, when considered individually, there is no evidence at present that even lifelong exposure is expected to have any adverse health impacts. Individual steps in the derivation of guide value II are: i) identification of the critical study and the Point of Departure (POD), conversion from short term to continuous exposure by adjustment for ii) study length (subacute - subchronic - chronic) and iii) exposure duration (hours/day and days/week), extrapolation from animal to man by iv) interspezies variability (allometric, toxicokinetic and dynamic factors), consideration of sensitive individuals by v) intraspecies variability (kinetic and dynamic factor), and vi) physiologic differences within the population( i.e. children factor), and finally vii) consideration of the quality of database. The quality of the pivotal study is assessed according to the criteria proposed by Klimisch et al. (1997). The assessment factors have been harmonized with recent recommendations by WHO (IAQG 2010) and ECHA guidance document R 8. RW I is derived from RW II by introduction of an additional factor (usually 10) but can also be derived if no reliable LOAEC is available from a "No observed adverse effect concentration" (NOAEC).A template containing the key information on the chemical and the critical study and transparently presenting the assessment factors and derivation of the guide values and a glossary of terms complete the recommendation.