Arsenic excretion in healthy adult Norwegians a randomized controlled seafood diet trial

1
Arsenic excretion in healthy adult Norwegians- a
randomized controlled seafood diet
trial Marianne Molin1, Vibeke H. Telle-Hansen1,
Lisbeth Dahl 2,, Stine M. Ulven1, Marianne
Holck1, Arne Oshaug1, Kåre Julshamn2 and Helle
M. Meltzer3 1 Akershus University College,
Norway 2 National Institute of Nutrition and
Seafood Research (NIFES), Norway 3 Norwegian
Institute of Public Health, Norway
Akershus University College
Background Norwegian adults are exposed to
arsenic (As) mainly through seafood, where it is
mostly present in the non-toxic, organic
arsenobetaine form. In order to assess the
toxicological impact of As intake from seafood on
human health, data on exposure and excretion of
As species are required. Aim The aim of the
present study was to investigate arsenic dietary
intake, metabolism and urinary excretion. The
specific purpose was to investigate whether the
amount of total As (tAs) in urine reflects the
amount in consumed diet and to examine how
rapidly tAs is cleared from urine. Method
Thirty-eight (28 women, 10 men) healthy,
non-smoking Norwegians aged 20-40 years were
included in a controlled diet trial and
randomized into four groups. After a 7-day run-in
period where the subjects refrained from food
items high in As (seafood, mushrooms, rice/rice
products and dietary supplements), each group
consumed an As-rich meal containing either 150
grams of cod (754 µg tAs), salmon (167 µg tAs),
blue mussel (632 µg tAs) or potato (control) (lt 5
µg tAs). All urine was collected for 72 h after
ingestion of the meal and in this period the
participants were given a similar, strictly
controlled diet low in As.
Study design The participants were divided into
four groups. Each group consumed either 150 grams
of cod (Gadus morhua, L.), blue mussel (Mytilis
edulis), salmon (Salmo salar ,L.) or potato
(control) as a breakfast meal (pie). All meals in
the strictly controlled diet the following 72 h
were served at the University College. Collection
of urine Participants were requested to collect
morning urine samples at day -7, 0 and 7. In
addition the participants were requested to
collect 72 h urine (collected in 3 batches on day
0, and 24 h urine on day 1 and 2).
Table 1 Baseline characteristics of the
participants Both genders between 20-40 years
were included and were non-smoking, non-pregnant
or lactating and healthy (CRP lt 10) (Mean SD).
Figure 1 Study design. Between day -7 and day 0,
the participants were randomized into four
groups cod, salmon, blue mussel and potato
(control). The participants kept restrictions
during the whole study period starting on day -7
no seafood, no rice- or rice products, no
mushrooms or dietary supplements. On day 0 the
participants consumed an arsenic-rich meal for
breakfast (pie) containing 150 g seafood or
potato. The following 72 h the participants were
given a strictly controlled diet low in arsenic
and in this period all urine was collected.
Determination of total arsenic in food and urine
Samples of the arsenic-rich meal (pie) and double
portions of all meals in the strictly controlled
diet were homogenized and freeze dried before
digestion with nitric acid and hydrogen peroxide
in a microwave oven. The determination of total
arsenic (tAs) in food and urine was carried out
by inductively coupled plasma-mass spectrometry
(ICP-MS).

Figure 2 Mean concentrations of total arsenic
excreted in urine from baseline (day -7) and 72h
after intake of an arsenic-rich meal. The first
24 h after the arsenic-rich meal urine was
collected in 3 batches (from the arsenic-rich
meal until 2 pm, 2 pm-7 pm, 7 pm until morning
urine), the following 48 h 24h urine were
collected.
Results Amount tAs from the As-rich meal and the
strictly controlled diet and the amount tAs
excreted in urine during 72 h after the meal was
ingested are given in Table 2. The excretion of
tAs in urine in the different samples analyzed
during 72 h after the meal is given in Table 3.
Figure 2 shows how the concentration of tAs in
urine changed during 72 h after intake of the
arsenic-rich meal.
Table 2 Total arsenic ingested and excreted
during 72 h. The tAs from the analyzed samples of
the double-portions from the strictly controlled
diet is included in the ingested tAs
(contributing 118 µg total As).
Analyzed values (uncertainty in the ICP-MS
method).
Conclusion The results show that the amount
excreted tAs in urine reflects the amount tAs in
the consumed diet. However, the percentage
excreted was substantially lower than expected,
which warrants further investigation. We also
conclude that most arsenic is cleared from urine
within 72 hours.
Table 3 Excretion of total arsenic in urine
after intake of an arsenic-rich meal (breakfast
pie) (Mean ( SD)).
This study was funded by the Norwegian Research
Council (project no. 142468/140)