The mixture assessment or allocation factor: conceptual background, estimation algorithms and a case study example

Environmental Sciences Europe

Table 3 Consequences for MAF_exact and MAF_90% when the “true” risk of the most important mixture component is under- or overestimated by a factor of 10

	Mixture 1 (actual risk)	Mixture 1 (underestimated risk)	Mixture 1 (overestimated risk)
RQ Substance 1	5	0.5	50
RQ Substance 2	4	4	4
RQ Substance 3	0.5	0.5	0.5
RQ Substance 4	0.2	0.2	0.2
RQ Substance 5–10	0.05	0.05	0.05
RQ sum	10	5.5	55
MAF_90%	2	3	1
RQ sum after applying MAF_90%	2	1.5	55
MAF_exact	5.7	5.7	5.7
RQ sum after applying MAF_exact	1	1	1

Despite the RQ of the most important compound being under- or over-estimated by a factor of 10 (see boldfaced values), MAF_exact remains unchanged, in contrast to MAF_90% (which consistently leads to a residual risk exceeding 1)