EU-SICHERHEITSDATENBLATT Dieselkraftstoff ... - Schmierstoffe

1.2.1.4. Acute aquatic toxicity model
Utilizing an acute toxicity database for guppies, Verhaar et al. (1992) delineated the
classes of inert, less inert, reactive, and specifically-acting chemicals, and provided the
chemical rules for discrimination of the first three groups. Using a broader set of
chemicals tested with fathead minnow in combination with concordant information about
the primary mode of toxic action, Russom et al. (1997) established seven toxicodynamic
categories, including three types of narcosis-acting chemicals, oxidative phosphorylation
uncouplers, reactive electrophiles/pro-electrophiles, acetylcholinesterase inhibitors and
central nervous seizure agents. The two independently developed classification schemes
bear common features. Both systems delineate inert chemicals, or Type I narcotics, less
inert chemicals, or Type II narcotics, and reactive electrophiles/proelectrophiles.
Categorization of chemicals according to their mode of action (MOA) was further
adopted by LMC by postulating the so-called toxic response surface. In this approach 2-
D structural information is used only to identify the MOA of chemicals. Based on
theoretical and empiric knowledge the following seven hierarchically ordered MOA are
distinguished:
Reactive Unspecified
Aldehydes
alpha, beta-Unsaturated alcohols
Phenols and anilines
Esters
Narcotic amines
Basesurface (non-polar) narcotics
The toxicity of chemicals showing different MOA is predicted on the basis of
interspecies models with the following mathematical structure (Dimitrov et al. 2000,
2003 and 2004):
log
Species
1/
C b b BCF
b R
1
0
log
tox
2
where BCF tox is the bioconcentration factor corrected for the effect of internal organisms
water phase [10], R is a global or local reactivity parameter specific for each MOA, C is
the concentration in mol/l causing specific toxic effect, such as 50% lethality,
Species
immobilization, inhibition of bioluminescence, etc., and
b 0
,
b 1 , and
b2
are adjusted
model parameters. Chemicals with an unknown MOA or with insufficient number of
data for model building are classified in the category Reactive Unspecified MOA. For
these chemicals the minimum toxicity is predicted by making use of the model for nonpolar
narcotics:
log
1/
C
log1
C
Re activeUnspecified
/
Non
polarnar cot ics
The applicability domain of chemicals with Reactive Unspecified MOA is not estimated.
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