Old Kick-off Values (2005)

For chemical substances without a health based OEL but with C&L we established the concept of the so-called Kick-off values, using designated R-phrase(s) assigned of the substances.
Click here to go directly to the table with the Kick-off values.


A Kick-off value of a substance is defined as equal to the 10%-tile lower tolerance limit of the limit value in the highest hazard-class in which the substance is classified on the basis of its R-phrases. The “real” dose-response Health Based Occupational Hygiene Limit Value of the substance is at least with a probability of 90% above this kick-off level.


The advantage of a Kick-off value at a technical and economic feasible level, is that the (expensive) procedure to a to establish a formal limit value can be omitted. If the Kick-off Value is not technically or economically feasible, then the procedure to establish a more accurate and often higher limit, can still be started (a.o. (animal) experimental or epidemiological studies, with extrapolation factors).


The Kick-off values (only as TWA 8 hours) are based on the study of Scheffers and Wieling, published in 2005 (Journal of Applied Occupational Sciences [Tijdschrift voor toegepaste Arbowetenschap (TtA)] vol. 18, 2005, p. 67-75; in Dutch, with English summary). Click here to upload the article (pdf-format).




Derivation of Kick-off Values

The kick-off threshold level of a substance without formal OEL follows from the R-phrases for damage to health and the physical state. Start by selecting in the Table below (Table 8 of the article) the R-phrases of the substance which identifies the highest risk category for the substance. Read in the underlying cells of the hazard class column the derived Kick-off value, depending on whether the dust and aerosols, or gas / vapor level exceeds the kick-off value.

Table:  Kick-off values (TWA 8 hr) based on the TRGS440 Hazard Class Scheme

Hazard Class






36, 37, 38, 65, 66, 67* 20, 21, 22 34, 41, 62, 63, 64 23, 24, 25, 29, 31, 33, 35, 40, 42, 43, 48/21,22,23, 60, 61, 68 26, 27, 28, 32, 45, 46, 48/23,24,25, 49
Kick-off Limit depending per physical state:
Gases and vapors (ppm)





Aerosols (mg/m3)





*: R65, 66 and 67 are only linked to gases and vapors (values in ppm)



Table 1 in the article shows the hazard classification of five classes of ordering schemes based on the R-phrases. As the box plots in Table 3 of the TtA-article are difficult to read, click here the open Table 3 in pdf-format. In the links below you will find the following information for all investigated orderings schemes:

  • the log-probality distributions
  • the scatterplots with regression

Click on the desired classification scheme: