3.3.3           Weighting category human toxicity

The acute toxicity of chemical substances can be judged by the assistance of three impact categories: MAK  (workplace threshold value, Maximale Arbeitsplatzkonzentration), hazard sign, or LD50-, LC50-values, respectively. Using logarithmic functions, similarly to the methodology in ‘claiming of resources’ (impact category substance price), weighting factors Q were assigned to MAK-, LD50-, LC50-value-ranges, respectively, which will be produced from the pair of value indicated.

Table 3         f(MAK) and f(LX50-value) with X = C or D and (x/y)-pairs of value 1 and 2 for the calculation of functions f(Q). (‘[]’ is the integer function of Gauß, i.e., e.g. [2.3] = [2.98] = 2)

f(MAK) and f(LX50-Wert)

Pair 1 (Q / LX50)

Pair 2 (Q / LX50)

Q = [ln(MAK/28284)/-1.3246]

Q = 2 / MAK 

= 2000 mg/m3

Q = 10 / MAK 

= 0.05 mg/m3

Q = [ln(LC50 inhal../68.39)/-0.6148]

(Q = 2 /  20 mg/l /4h)

(Q = 8 /  0.5 mg/l /4h)

Q = [ln(LD50 oral/8615)/-0.7303]

(Q = 2 /  2000 mg/kg)

(Q = 8 /  25 mg/kg)

Q = [ln(LD50 dermal/17230)/-0.7303]

(Q = 2 /  4000 mg/kg)

(Q = 8 /  50 mg/kg)

f(MAK) and f(LX50-value) result from the exponential functions f(Q) = MAK = 28284 × e-1.3246×Q LC50 inhal. = 68.39 × e-0.6148×Q, LD50 oral = 8615 × e-0.7303×Q, and LD50 dermal= 17230 ×e-0.7303×Q. The hazard sign (Xn, T, or T+) were assigned to the values Q = 4, 7, and 10 (Table 4). The value-ranges for the workplace threshold value and the LD50-, the LC50-values, resp., are shown in Table 4 and Table 5.

 

Table 4         Assignment of MAK-value-ranges and symbols of danger to the weighting factor QHuman toxicity (acute)

Q

 

MAK-range [mg/m3]

 

hazard sign

1

7520.98

to

1999.90

 

2

1999.90

to

531.79

 

3

531.79

to

141.41

 

4

141.41

to

37.60

Xn

5

37.60

to

10.00

 

6

10.00

to

2.66

 

7

2.66

to

0.71

T

8

0.71

to

0.19

 

9

0.19

to

0.05

 

10

0.05

to

0.00

T+

             

 

Table 5         Assignment of LD50-, resp. LC50-value-ranges to a weighting factor Q

Q

hazard sign

 

way of intake

 

 

 

LC50 inhal. [mg/l /4h]

LD50 oral [mg/kg]

LD50  dermal [mg/kg]

1

 

36.98

to

20.00

4150.40

to

1999.52

8300.80

to

3999.03

2

Xn »

20.00

to

10.81

1999.52

to

963.30

3999.03

to

1926.59

3

Xn »

10.81

to

5.85

963.30

to

464.08

1926.59

to

928.16

4

Xn »

5.85

to

3.16

464.08

to

223.58

928.16

to

447.16

5

Xn, T »

3.16

to

1.71

223.58

to

107.71

447.16

to

215.42

6

T »

1.71

to

0.92

107.71

to

51.89

215.42

to

103.78

7

T »

0.92

to

0.50

51.89

to

25.00

103.78

to

50.00

8

T+ »

0.50

to

0.27

25.00

to

12.04

50.00

to

24.09

9

T+ »

0.27

to

0.15

12.04

to

5.80

24.09

to

11.60

10

T+ »

0.15

to

0.00

5.80

to

0.00

11.60

to

0.00

                           

The weighting factors Q of the value-ranges presented in Table 5 fairly well agree with the assignment (made in Table 4) of the weighting factors Q to the hazard signs Xn, T, and T+, which were listed in the column ‘hazard signs’ according to the legal restraints from Table 6.

Table 6         Classification criteria and selection of hazard sign according to 67/548/EEC Appendix 6(2)

hazard sign

 

way of intake

 

 

inhal. [mg/l /4h]

oral [mg/kg]

dermal [mg/kg]

T+

 

 

LC50

<

0.5

 

 

LD50

<

25

 

 

LD50

<

50

T

0.5

<

LC50

<

2

25

<

LD50

<

200

50

<

LD50

<

400

Xn

2

<

LC50

<

20

200

<

LD50

<

2000

400

<

LD50

<

2000

The sequence of priorities prefers the program-internal use of MAK-values instead of the symbols of dangers and the symbols of dangers instead of the LD50-, resp. LC50-values.

 

Back to Main Menu Next Chapter