3.3.8           Weighting category Accumulation

The enrichment of chemical products in particular environmental compartments is termed accumulation. Organisms assimilate substances by their nourishment (bio-magnification), by the surrounding medium (bio-concentration), or by both ways (bio-accumulation). Ecological magnification, i. e., a substance’ concentration increase in an ecological system or a food chain at transition from a lower to the next higher trophic  level, can result in consequence and, especially, jeopardize the human being situated at the end of the food chain, who mostly himself is the initiator of the immissions of problematic substances.

At the bio-accumulation we do not regard absolute concentrations but the relation of the concentration in the organism to that of its environment. The accumulation of substances in the organism depends on the environmental concentration, the level of the internal assimilation, and the passive (diffusion processes) or active (enzymatical detoxification) segregation. By the help of freely accessible software, logKow-values (octanol/water-distribution coefficients) of substances can be determined simply after input of their structure and used for the estimation of the accumulation instead of BCF-values to be gained expensively in an experimental way. According to the international convention, a substance is classified as accumulating if the logKow > 3 (national logKow > 2.7 in Germany). Therefore, the assignment of logKow-ranges to weighting factors Q in the EATOS program is made starting from the lowKow-value 3 (Table 11) with the function  with  or logKow. The program-internal assignment of the substance-specific weighting factor Q concerning the accumulation is made primarily according to the BCF-value and – if this does not exist – according to the Kow-value. Table 11 represents this assignment.

 

Table 11  Assignment of , resp. logKow-ranges to the weighting factor QAccumulation

Q

 

log(BCF/0.048)- resp. logKow-range

 

1

3.00

to

3.33

2

3.33

to

3.67

3

3.67

to

4.00

4

4.00

to

4.33

5

4.33

to

4.67

6

4.67

to

5.00

7

5.00

to

5.33

8

5.33

to

5.67

9

5.67

to

6.00

10

6.00

to

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