APROBA-Plus is a user friendly excel tool that facilitates probabilistic risk assessment of substances, including uncertainty analysis. The use of APROBA-Plus is recommended for practically all substance risk assessments. Its outcome helps risk managers to make decisions. The tool compares a high exposure to the dose which causes a particular adverse health effect in sensitive individuals. Rather than comparing (conservative) point estimates for the effect dose and exposure, the entire uncertainty distribution of both inputs is included in the analysis. The resulting plot transparently visualizes the uncertainty about the distance between hazard and exposure.


The tool is developed as an addition to the WHO-IPCS tool APROBA, which is a part of the guidance on “Evaluating and expressing uncertainty in hazard assessment” (2017). APROBA can do probabilistic calculations in an approximate but quick and easy way assuming that the uncertainties in the different aspects of the hazard characterization (such as Point of Departure, inter-, and intraspecies extrapolation) are lognormally distributed. This results in a probabilistic health-based guidance value rather than the usual deterministic point estimate (such as RfD, ADI). In the extended APROBA-plus, exposure estimates with an uncertainty range can be included to create a single plot, which visualizes the uncertainties in exposure and hazard.

By making the uncertainties visible, the outcome from a risk assessment becomes more transparent and informative than the more usual deterministic approaches, so that risk managers can make better informed decisions, e.g. directly taking measures or asking for refinement of the risk assessment. If the latter, APROBA-Plus can help in showing which aspects in the risk assessment contributed most to the overall uncertainty, as an indication what type of refinement would be most effective.


APROBA-Plus is a free tool and comes with absolutely no warranty. Adequate use and interpretation of the results is required when used as a basis of risk assessment. RIVMNational Institute for Public Health and the Environment is not responsible for the consequences of the operational use of APROBA-Plus.

System requirements

The APROBA-Plus tool is a Microsoft Excel file, and does not require installation, macros or administrator rights to get it working.  Using APROBA-Plus requires Microsoft Excel 2010 or higher.  

Contact information

Questions, comments and suggestions to improve APROBA-Plus can be send to  aproba-plus@rivm.nl