For the comparison of exposure with dose-response information from hazard studies, it is often convenient to express the retained alveolar dose in a specific normalisation (see, for example (Brown et al., 2005)) . Normalisation of the load on a physiological scale allows usually for a more meaningful comparison of doses across species (man and rat, in the case of ConsExpo nano) or for a better scaling between in vivo and in vitro systems. Normalisations that are frequently useful are: the retained dose per kg body weight, per g lung, per unit of the alveolar surface area. Less frequently used normalisations include: the retained dose per alveolus or per alveolar macrophage.
ConsExpo nano facilitates all these normalisations. The user has to provide input on specific physiology such as lung and body mass, surface area of the alveolar epithelium. ConsExpo nano provides defaults for all these parameters for both human and rat. Defaults are taken from (Brown et al., 2005) .
|Normalisation||Divide by (defaults)|
|Total retained (default)|
|Per kg body mass (/kg)||Body weight||65 (kg)||330 (g)|
|Per g lung mass (/g)||Lung weight (g)||1100||1.7|
|Per m2 alveolar area (/m2)||Alveolar area (m2)||57||0.30|
|Per alveolus (-)||Number of alveoli||5 x 108||2.0 x 107|
|Per alveolar macrophage||Number of alveolar macrophages||6 x 109||3 x 107|