Intake of fish-derived compounds in infants

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Scope

What is the intake of fish-derived compounds in infants (below 1 year of age)?

Boundaries:

• Averaging: A random individual
• Spatial: In Finland
• Temporal: Current situation

Definition

Data

There are several possible pathways of intake:

1. Being exposed to the compounds in utero, so that there is a body burden at birth.
2. By breast feeding.
   1. Exposure based on mother's current diet.
   2. Exposure based on mother's body burden (because of previous exposure).
3. Eating fish-containing food.

In utero exposure

Placental concentrations of PCDD/Fs and methyl mercury can be used as proxies of body burdens at birth. Whether these should be transformed into other units (concentrations in child, or steady state daily intake), needs to be discussed.

Breast feeding

Prevalence of breast-feeders

Age (mo)	Additional breast-feeding	Only breast-feeding
1	0.92	0.58
3		0.33
4	0.72	0.21
6	0.58	0.01
Average time	7 mo	1.4 mo

Exposure based on mother's diet

If the infant is only breast-fed, he gets 100 % of his energy intake from mother's milk. It can be reasonably assumed that the infant gets the same proportion of other compounds from mother's milk as what he gets energy. The concentrations of these compounds in mother's milk, on the other hand, are relative to their amounts in mother's diet. Of course, there may be large deviations from this assumption depending on the compound, but these are not dealt with in this phase.

Energy intake recommendations in Finland

Age	Energy (MJ/day)
0-3 mo	1.3-2.2
4-5 mo	2.6-2.7
6-12 mo	2.6-3.7
12-23 mo	3.4-5.5
2-5 a	5.3-6.3
6-9 a	7.2-9.2
Boys
10-14 a	9.4-10.8
15-18 a	11.3-13.4
Girls
10-14 a	8.2-9.5
15-18 a	9.6-9.9

Therefore, fish intake is a product:

Ii = Σt It,m * (Et,i/Et,m) * Ft,i,

where I = annual intake, E = energy intake, F = fraction of the breast milk from the total diet, t = time, i = infant, m = mother. As a first proxy, F is 1 with breast feeding only, 0.5 with additional breast feeding, and 0 otherwise.

Mother's body burden

In the case of PCDD/Fs, the mother may have a large body burden already before pregnancy, and these pollutants are then transferred to the infant during breast-feeding. Even 25 % of mother's PCDD/F body burden may be transferred to the infant during breast feeding .

The average contaminant intake is

Ic,i = C0,m * mm * (1-e-kntn),

where C₀ is the concentration in the beginning, k_n = elimination constant for the compound in the mother due to nursing, t_n = length of the nursing period, c = compound, n = nursing.

For PCDD/F (see above), k_n can be calculated from

1-e-kn*0.5 a = 0.25 ⇔ kn = 0.575364 1/a

Fish-containing food

The recommendation is that infants don't eat fish at all before 6 months of age, and it is gradually added to the diet. Therefore, it can be assumed zero intake until 6 mo, and then a linear shift to the individual fish intake level at 1 year of age.

Unit

g/day (of fish), or g/day (of a specific compound); the matrix must be specified!