- Practical Guide -

Page 76 of 153

In conformity with Article 4 (b) in Directive 2002/72/EC, the specific limits expressed in

mg/kg shall be divided by the conventional conversion factor of 6 in order to express them in

mg/dm

2

. For the above additive (Irganox 1076) the specific limit is now 6/6 = 1 mg/dm

2

<

2.8 mg/dm

2

. The sandwiches with fatty substances on the surface belong to the category of

food with the reference number 08.08 in the Directive 85/572/EEC and the reduction factor

X/5 can be used. This means in the above example: (m

F,t

/A)/5 = 0.56 < 1 mg/dm

2

and,

consequently, it is in compliance with the Directive 2002/72/EC.

For the second additive, Irgafos 168 (PM/REF = 74240), with the molecular weight M

r

= 647

a smaller migration rate results (Eq.2) as for Irganox 1076 with M

r

= 531. With the tenfold

higher migration limit (SML = 60 mg/kg) no further investigation of the specific migration is

necessary.

**Example 2:**

A film of LDPE (100

mm) is used in the same way as in example 1 but the origin of the

plastic is unknown.

*Which informations can be obtained from mathematical modelling about the specific*

migration of any additives possibly contained in the film?

From the previous example we know that a reduction factor X/5 can be used. That means the

film is in compliance with the Directive 2002/72/EC if (m

F,t

/A)/5

£ SML/6 = 1 mg/dm

2

because for most additives in table 4 the specific migration limits are SML

³ 6 mg/kg. Let us

start with the additive with the smallest molecular weight, Mr

i

= 214 and SML = 6. As in the

first example an initial concentration of 0.5% (5000 mg/kg) is assumed as an upper limit.

Modelling with the software:

...can be done with the aid of the previous File Ex1 (saved under Example1) and requires to

provide the following informations:

1.

Information about the migrateable substance

® user defined migrateable substance ®

molecular weight **(214)**

® OK

Calculation of migration:

® Estimation ® TDM ® TDM + E1.

Result: m

F,t

/A = 4.7 mg/dm

2

.

Discussion of the result:

With the reduction factor X/5 the final result is (m

F,t

/A)/5 = 0.94 < 1 mg/dm

2

.

Consequently, for all additives in table 4.2.1 with M

r

> 214 and SML

³ 6 the film can

be considered to be in compliance with the Directive 2002/72/EC because the

migration decreases with increasing M

r

.

By repeating the calculations in the same manner for the remaining additives in table

4.2.1 the estimated migration values exceed the corresponding SML values for 5

additives with the following PM/REF: 38560, 38820, 46640, 60320, 95270.

If one decides to extract all the migrants from the LDPE film using an adequate

method, e.g. hot toluene for solving and methanol for re-precipitation, then a quick

semi-quantitative analysis is sufficient for a decision of necessary further investigation.