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The DNELator

The DNELator is an on-line tool that facilitates the process of calculating a Derived No Effect Level (DNEL) by guiding the user step-by-step through the official technical guidance published by the European Chemicals Agency (ECHA) as part of the REACH regulation.

Under REACH, DNELs must be established for substances manufactured or imported in quantities exceeding ten tonnes per annum. This information is then declared in the chemical safety report (CSR) and safety data sheet (SDS).

What does the DNELator do?

The DNELator has been programmed to guide you through the current ECHA guidance document R8. It assists with these steps:

  • collecting together typical dose descriptor(s) (NOAEL, NOAEC, Benchmark Dose, etc.)
  • modifying the dose descriptor(s) to the correct starting point
  • applying assessment factors to the correct starting point to obtain the DNEL(s)

What inputs does the DNELator require?

In order to calculate a DNEL, you need some information about the biological effects of the substance in question, about its usage and target population, and about the existing dose descriptors. You will need:

  • At least one dose descriptor. Common types of dose descriptor are benchmark doses (BMDs and BMDLs), NOAELs and LD50s.
  • Knowledge of adverse responses. You need to know, for example, if the substance has carcinogenic or mutagenic effects; if it causes irritability or skin sensitivity; and if the effects are local or systemic.
  • Knowledge of how the substance is used. Is it for workers or the general population? Are there sensitive subpopulations like children or pregnant women? How often and how long is it used for? What are the routes of exposure?

What are the benefits of using the DNELator?

REACH guidance can be complex and becoming conversant with the REACH technical guidance document can be very time consuming. The DNELator guides you step by step through the process;

  • The DNELator is web-based, so does not require any installation.
  • The DNELator is easy to use and requires no specific training. Its step-by-step process only prompts you for the relevant information.
  • In most cases, you will only need a basic understanding of the technical guidance to calculate a DNEL.
  • The DNELator will often speed up the process of calculating DNELs.
  • You can be confident that your DNELs will be calculated in accordance with the official ECHA technical guidance.
  • The DNELator's automated calculation reduces the possibility of human error.
  • The DNELator produces a full report showing you the route taken to perform the calculation, allowing you to demonstrate your derivation process in a consistent and transparent way.

Can I try the DNELator?

Anyone can set up an account and can use the DNELator to work through a scenario up to the point of the actual calculation and result. This allows you to put in your data and to see whether you are able to perform a valid calculation.

Viewing the result and calculation.

 In order to view the result and calculation route, you will be required to purchase the appropriate number of credits from the HSL Store. The DNELator uses the concept of exposure populations and a credit is required for each of the exposure populations you have specified as part of your scenario. There are three possible exposure populations: workers, consumers and humans via the environment. Dependent on your circumstances as a registrant, it may not be necessary to derive DNELs for all the populations. Just before you buy your scenario, you will be informed how many credits you need to buy. If you need to calculate DNELs for more than one scenario or substance, then you can purchase credits in advance which will be stored against your account until required.

Where can I find out more?

For more details on the DNELator and to set up your free account, visit

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