1. Toxicity

Chemicals can be toxic, by which we usually mean that they are, to a greater or lesser extent, toxic to humans. This toxicity can have consequences, both in the short and the long term. In the first case we speak of acute toxicity and in the second case of chronic toxicity. In the latter case we think of e.g. carcinogenic, mutagenic or reprotoxic (CMR) effects.

Is a toxicity rating available?
Two simple rough-and-ready rules to get a first impression of the toxicity of chemicals are : watching their classification on the label or in the SDS (SDS), or looking at already established limits. 

On the basis of the classification
Through a critical look at the classification of the hazardous product according to DSD / DPD (Dangerous Substances directive / dangerous preparations directive) or CLP / GHS(classification, labeling and packaging / globally harmonized system), you can quickly assess the dangers. Where severe acute or chronic effects are possible, the risk is the greatest. Early 2012, The FPS ELSD published a poster (Dutch and French) in which the old and new system are compared to each other and one gets an overview of all hazardousproperties, based on the classification. If an MSDS is not available, you may have to check the websites of the suppliers, or paying databases. A free alternative are the International Chemical Safety Cards (ICSC) where a lot of basic information, also about the toxicity, is summarized, per substance.

On the basis of limit values
In the table below, there are two commonly used, simple interpretations of the toxic characteristics of a product, on the basis of defined limit values:

Toxicity class Method 1   Method 2
  as gas/vapor (in mg/m³) as aerosol (in mg/m³) as gas/vapor (in ppm)
low toxicity >1000 >10 >500
average toxicity 100-1000 1-10 10-500
high toxicity 10-100 0,1-1 0,1-10
very high toxicity <10 <0,1 <0,1

There is no toxicity assessment available?
Do not worry, there are many (free) databases in which you can search for the toxic properties of substances and products. You can make your own assessment in for instance threesteps:
Step 1: Collect toxicity information: Patchwork (Dutch) is here a great tool. In this PDF flowchart there are hyperlinks to all major free Internet databases
Step 2: on the basis of this, establish a critical effect (for example, on the basis of the lowest DNEL, NOAEL, ... for a specific effect)
Step 3: on the basis of this, determine the toxicity class, such as:

  • class 0: little toxic, effect only occurs on excessive exposure
  • class 1: slightly toxic, effect is reversible, but some nuisance
  • class 2: moderately toxic, effect occurs but the damage is not permanent
  • class 3: very toxic, effect occurs and damage is permanent
  • class U: unknown, no data on occurrence of the effect


  • AEGLs concentration guidelines of the American EPA for a single exposure to acute toxic substances with high priority (emergency planning)
  • ERPGs concentration guidelines of the American AIHA for a single exposure within the framework of accident prevention and emergency planning
  • EPA IRIS assessments
  • IARC Monographs
  • Intervention values Dangerous Substances 2007 (Dutch) Dutch set of health-based limit values to determine the risk level for social workers


  • BMDS Benchmark Dose Software
  • Demeter (French) INRS database reprotoxic compounds
  • ECHA C&L click "CL Inventory" to find the classification of a substance
  • GESTIS Substance Database
  • MIXIE Canadian platform to assess toxicological effects of combinations of dangerous substances (some 700), on the basis of literature data
  • Patchwork (Dutch) helps you to choose the right databases to get an answer to your question