We regret to say that we can no longer guarantee correct functioning of ETX 2.2 under current versions of Windows 10.

ETX 2.2 needs to be updated to make it compatible with modern versions of Windows. This update is currently ongoing and will hopefully be finished within the coming months. We apologize for any inconvenience this may cause.

This software program calculates a (log) normal distribution through toxicity data entered by the user.

This gives a species sensitivity distribution (SSD). This distribution is subsequently tested for statistical criteria on normality. The estimated 5th percentile and median of the calculated distribution are presented, each with their respective two-sided 90% confidence interval. With the calculated SSD the fraction of affected species at a given environmental concentration can be estimated, or an expected ecological risk (EERexpected ecological risk ) at a series of environmental concentrations. The program also offers the opportunity to estimate the 5th percentile of very small data sets using the so called small sample method.


The techniques offered with ETX are used in risk assessment and in derivation of environmental quality standards (EQSEnvironmental Quality Standards ) in the Netherlands and Europe. The techniques are frequently used in the field of ecotoxicology. The purpose of ETX 2.2 is to offer the user the calculation methods as described in the scientific literature. You can find an overview of the underlying literature in the Manual.

Download ETX

Download the program ETX 2.2

To install the program, download the file named ETX 2.2 onto your computer. Double clicking the file will invoke the program installer, which takes you through the installation process in just a few steps.
It is strongly advised to uninstall the previous ETX version before installing ETX 2.2. The Microsoft .NET framework is a prerequisite for installing ETX 2.2. However, this software package is already preinstalled with Windows. In case it is not, the .NET framework version can be downloaded for free from the Microsoft website. 

Please note the following:
With this update (september 2017) issues with the decimal separator that occurred in the previous version (2.1) are solved. The program also contains an automatic update warning. If you run ETX 2.2 on a computer with an internet connection, a message will appear in the top of the ETX window, indicating that an update can be downloaded.


Download the Manual ETX 2.0

The technical and scientific description in the manual still apply to ETX 2.2 as the content of the software was not changed since version 2.0. Only the section of the manual pertaining to the installation procedure described in the manual of ETX 2.0 is outdated.

Citing ETX

The current version of ETX can be cited as ETX 2.2. The preferred citation can be found in the manual.


The current version (ETX 2.2) of this program was released in September 2017. The previous version ETX 2.1 was released in February 2015 and the first version (ETX 2.0) was released in 2004. The current update does not concern any technical, scientific changes.

Tips, wishes and comments

There is no helpdesk to answer questions of users. However, we welcome your comments on the program and its functioning at