04/15 - Trattamento dei dati inferiori al limite di rivelabilità nel calcolo dei risultati analitici. A cura di Edoardo Menichini, Giuseppe Viviano e il Gruppo di lavoro Istituto Superiore di Sanità Metodiche per il rilevamento delle emissioni in atmosfera da impianti industriali 2004, v, 19 p.

Treatment of data below the detection limit in the calculation of analytical results.
Edited by Edoardo Menichini, Giuseppe Viviano and the Working group Istituto Superiore di Sanità Metodiche per il rilevamento delle emissioni in atmosfera da impianti industriali"
2004, v, 19 p. Rapporti ISTISAN 04/15 (in Italian)

When calculating the mean concentration of a data set or the cumulative concentration of various substances, the choice of the calculation method for dealing with data below the Limit of Detection (LD) may affect, in particular, the compliance with the emission limit value. The objective of this document is to provide one method allowing an uniform approach and evaluation by different laboratories performing analytical controls. Substituting Not Detected (ND) data with a value equal to LD/2 results to be the optimum solution: it represents a balance point between the solutions which underestimate (ND = 0) or overestimate (ND = LD) the true value, is reasonably precautionary in health-related studies, is feasible, and in agreement with the conclusions of various literature studies and with the approaches followed by other bodies. This solution requires using analytical methods with a low LD with respect to the emission limit value.
Key words : Compliance, Emission analysis, Emission limit values, Not detected