I am sending a copy of an article about sea weeds and heavy metals: i
think there are a lot of factors that affect the level of heavy metals
present in seaweeds..one important factor is the location or
environment where the seaweeds are grown, hence most research
activities are done with specific sites. this is only one article but
you can find more.
J. Agric. Food Chem., 50 (4), 918 -923, 2002. 10.1021/jf0110250
S0021-8561(01)01025-1
Web Release Date: January 19, 2002
Copyright © 2002 American Chemical Society
Heavy Metal, Total Arsenic, and Inorganic Arsenic Contents of Algae Food Products
C. Almela, S. Algora, V. Benito, M. J. Clemente, V. Devesa, M. A.
Suner, D. Velez, and R. Montoro*
Instituto de Agroquimica y Tecnologia de Alimentos (CSIC), Apartado
73, 46100 Burjassot (Valencia), Spain
Received for review August 1, 2001. Revised manuscript received
November 2, 2001. Accepted November 5, 2001. V.D. and M.A.S. received
Spanish Research Personnel Training Grants from the Generalitat
Valenciana (Conselleria de Cultura, Educacio i Ciencia) and Ministerio
de Educacion y Cultura, respectively.
Abstract:
The total arsenic, inorganic arsenic, lead, cadmium, and mercury
contents of 18 algae food products currently on sale in Spain were
determined. The suitability of the analytical methodologies for this
type of matrix was confirmed by evaluating their analytical
characteristics. The concentration ranges found for each contaminant,
expressed in milligrams per kilogram of dry weight, were as follows:
total arsenic, 2.3-141; inorganic arsenic, 0.15-88; lead, <0.05-1.33;
cadmium, 0.03-1.9; and mercury, 0.004-0.04. There is currently no
legislation in Spain regarding contaminants in algae food products,
but some of the samples analyzed revealed Cd and inorganic As levels
higher than those permitted by legislation in other countries. Given
the high concentrations of inorganic As found in Hizikia fusiforme, a
daily consumption of 1.7 g of the product would reach the Provisional
Tolerable Weekly Intake recommended by the WHO for an average body
weight of 68 kg. A more comprehensive study of the contents and
toxicological implications of the inorganic As present in the algae
food products currently sold in Spain may be necessary, which might
then be the basis for the introduction of specific sales restrictions.
During recent decades the eating patterns of the Spanish population
have undergone marked changes. Innovations in food technology,
together with the globalization of markets, have resulted in a
significant increase in the number of new foods, both fresh and
processed or semiprocessed, available to consumers. Among these
products, edible algae have come to form a common part of Spanish
diets. A very wide variety of products derived from macroalgae or
microalgae can be bought in Spanish stores, with over 30 products of
this type already available in 1993 (1).
Although macroalgae species are used as a source of hydrocolloids
(agar, carrageenans, and alginates), they are mainly used for food,
with the great advantage that they need minimum processing after
harvest (2). No data are available about the consumption of algae in
Spain, but this country does seem to be following trends seen in other
Western countries, which show an increase in the consumption of these
products in recent years (3), mainly among groups that could be
considered to be extreme consumers, such as people on macrobiotic
diets. Consumer interest in these products is due to their nutritional
properties, which, although varying from one type of alga to another,
can be said to have the following characteristics in general: a high
protein content, which in some species, Porphyra tenera and Palmaria
palmata, is almost as high as that of soybean (4); an amino acid
profile similar to those of leguminosae and eggs (4); high levels of
dietary fiber, which can be between 33 and 50% of the total product
(5); and high contents of minerals [calcium, potassium, sodium, iron,
iodine, magnesium, and phosphorus (3)] and of certain vitamins [A, B1,
B2, C, and folic acid (6)]. Furthermore, medical properties have been
described (anti-HIV and antitumor activities and potential
contraceptive effects) in relation to numerous edible algae (7).
Despite the nutritional properties associated with algae, there is
another aspect that should not be forgotten: their capacity to
bioaccumulate not only essential elements but also toxic elements such
as certain heavy metals and arsenic. This characteristic has
encouraged the use of algae as indicators of marine ecosystem
pollution (8, 9). The species of alga considered also affects the
metal content detected to a considerable extent, although variations
have also been demonstrated that are associated with both the origin
of the product, which reflects the pollution found in its natural
habitat (7), and the growth phase and time of year when the samples
are gathered (10, 11). As a result, in order to evaluate edible algae
and the dietary supplements derived from them, it is necessary to
quantify the contaminants (heavy metals and arsenic) they contain as a
preliminary step to evaluating their toxicological considerations.
Nevertheless, these products do represent a sample type that has been
studied very little from the standpoint of chemical safety, and their
contaminant content is regulated in very different ways by different
legislation around the world. In the European Community, Regulation
(EC) 466/2001 of the European Commission, dated March 8, 2001, which
stipulates the maximum content of certain contaminants in food
products (12), does not include algae food products; however, some
countries, such as France (5), do have specific regulation concerning
the use of seaweeds for human consumption. There is currently a lack
of legislation in this field in Spain.
Most research into macroalgae has focused on the study of minerals
rather than on toxic elements. What little information is available
about the lead and cadmium contents of such products sold in Spain is
restricted to certain specific aspects (1, 8), but none covers mercury
content. With respect to arsenic, algae are a primary accumulator in
the marine environment and represent an important stage in arsenic
metabolism through the food chain (13). Information on this
contaminant is also sparse and generally refers to levels of total
arsenic, which are not useful for evaluating the toxicological risks
associated with consumption. The safety of edible algae with respect
to this metalloid can be evaluated only after determining the content
of inorganic arsenic, a term that includes the most toxic species of
arsenic [As(III) + As(V)], based on which the WHO has established a
Provisional Tolerable Weekly Intake (15 g of inorganic arsenic/week/kg
of body weight) (14).
The quantification of inorganic arsenic in edible algae products is
faced with the problem of a lack of specific methodologies. Our
laboratory has developed a methodology involving the solubilization of
the sample with hydrochloric acid and extraction by means of organic
solvents (15) that has been applied successfully to a wide range of
fish products (16). One of the main objectives of the present study
was to assess the suitability of this methodology for determining
inorganic arsenic in edible algae products. The contents of lead,
cadmium, mercury, total arsenic, and inorganic arsenic in a range of
samples of algae sold in Spain were therefore determined. The results
obtained have been analyzed from legislative and health safety
viewpoints.
Materials and Methods
Instruments. Determination of total lead and cadmium was performed by
graphite furnace atomic absorption spectroscopy (GF-AAS) with a
Perkin-Elmer (PE) longitudinal AC Zeeman (Analyst 600) atomic
absorption spectrometer, equipped with a transversely heated graphite
atomizer and a built-in, fully computer-controlled AS-800 autosampler
(Perkin-Elmer Hispania, S.A., Madrid, Spain). Pyrolitic graphite
coated tubes with an integrated L'vov platform were used.
The determination of total and inorganic arsenic was performed with an
AAS model 3300 (PE) equipped with an autosampler (PE AS-90) and a flow
injection system (PE FIAS-400) in order to provide hydride generation
in continuous flow mode. The determination of mercury was performed
with a flow vapor generation-atomic fluorescence spectrometer (AFS;
Millennium Merlin PSA 10.025, PS Analytical).
Other equipment used included a Moulinex Optiquick Duo domestic
microwave oven (Moulinex, Valencia, Spain), with a maximum power of
900 W; a PL 5125 sand bath (Raypa, Scharlau, S.L.); a K 1253 muffle
furnace equipped with a Eurotherm Controls 902 control program
(Heraeus S.A., Madrid, Spain); a KS 125 basic mechanical shaker (IKA
Labortechnik, Merck Farma y Quimica, S.A., Barcelona, Spain); and an
Eppendorf 5810 centrifuge (Merck).
Reagents. Deionized water (18 M cm) was used for the preparation of
the reagents and standards. All chemicals were of at least pro analysi
quality or better. Commercial standard solutions (1000 mg L-1) of
As(V), Pb, Cd, and Hg were used (Merck). Calibration standard
solutions of As(III) were prepared from a reduced standard solution of
As(V).
As a reducing solution for arsenic hydride generation, sodium
tetrahydroborate(III) solution (1% m/v) was prepared by dissolving
NaBH4 powder in 0.7% m/v NaOH solution and filtering through Whatman
No. 42 paper. Fresh NaBH4 solution was prepared daily. As a reducing
solution that converts Hg(II) into Hg(0) vapor, 2% m/v SnCl2 was
prepared by dissolving SnCl2 powder in 33% v/v HCl (17). The matrix
modifier used for determining Cd and Pb was a mixture of H2PO4NH4 and
Mg(NO3)2 in 1% HNO3.
All glassware was treated with 10% v/v HNO3 for 24 h and then rinsed
three times with deionized water before use. The following certified
reference materials were employed: Fucus sp. (International Atomic
Energy Agency, Analytical Quality Control Services, Vienna, Austria);
BCR 060 (aquatic plant Lagarosiphon major) and BCR-279 (sea lettuce
Ulva lactuca), both from the Institute for Reference Materials and
Measurements (IRMM), Brussels, Belgium.
Sample Collection and Preparation. In Spain, macroalgae are rarely
sold fresh; most of them have undergone some form of processing
varying from simply drying in the sun to being baked in an oven or
flame-dried. These products tend to be sold under a specific name that
refers to a certain alga processed in a particular way. In this study,
18 products derived from samples of brown algae (12 samples), red
algae (4 samples), and green algae (2 samples), bought in stores in
the city of Valencia (Spain), were analyzed. The following derived
products were included: wakame and kombu, obtained respectively by
drying and cooking the brown algae Undaria pinnatifida and Laminaria
japonica; hijiki (Hizikia fusiforme) and arame (Eisenia bicyclis),
obtained by drying fresh algae; nori and yakinori, obtained
respectively by drying and baking the red alga Porphyra sp.; dulse,
obtained by drying the red alga Palmaria palmata (2); and AO-nori,
obtained by drying the green alga Ulva pertusa. The samples are sold
in a dried form, and therefore they were not freeze-dried. They were
crushed in a mill and stored at 4 C until analysis.
Determination of Total Arsenic (16). The samples (0.25 g) were treated
with an ashing aid suspension (20% m/v MgNO3 + 2% m/v MgO) and nitric
acid (5 mL of 50% v/v), evaporated to dryness, and mineralized at 450
C with a gradual increase in temperature. The ash was dissolved in
hydrochloric acid (6 mol L-1) and prereduced (5% m/v ascorbic acid +
5% m/v KI). The analytical conditions used for arsenic determination
by flow injection-hydride generation-atomic absorption spectrometry
(FI-HG-AAS) were the following: loop sample, 0.5 mL; reducing agent,
0.2% (m/v) NaBH4 in 0.05% (m/v) NaOH, 5 mL min-1 flow rate; HCl
solution 10% (v/v), 10 mL min-1 flow rate; carrier gas argon, 100 mL
min-1 flow rate; wavelength, 193.7 nm; spectral band-pass, 0.7 nm;
electrodeless discharge lamp system 2; lamp current setting, 400 mA;
cell temperature, 900 C.
Determination of Inorganic Arsenic (15). Water (4.1 mL) and
concentrated HCl (18.4 mL) were added to 0.50 g of sample. The mixture
was left overnight. The reducing agent was then added (1 mL of 1.5%
m/v hydrazine sulfate solution and 2 mL of HBr), and the sample was
agitated for 30 s. CHCl3 (10 mL) was then added, and after 3 min of
shaking and 5 min of centrifuging (2000 rpm), the chloroform phase was
separated. The extraction process was repeated two more times, and the
chloroform phases were combined and filtered. The inorganic arsenic in
the chloroform phase was back-extracted by shaking for 10 min with 10
mL of 1 mol L-1 HCl. The phases were separated by centrifuging at 2000
rpm, and the aqueous phase was then aspirated and poured into a
beaker. This stage was repeated once again, and the back-extraction
phases obtained were combined. The inorganic arsenic in the
back-extraction phase was determined by means of the following
procedure: 2.5 mL of ashing aid suspension and 10 mL of concentrated
HNO3 were added to the combined back-extraction phases, dry-ashed, and
quantified by FI-HG-AAS in the conditions described previously for the
determination of total arsenic.
Determination of Lead and Cadmium. The sample (0.20 g) was placed in a
high-pressure poly(tetrafluoroethylene) (PTFE) vessel. Two milliliters
of 65% HNO3 and 1 mL of 35% H2O2 were added. The vessel was sealed
with a screw cap and placed inside the microwave oven. Samples were
irradiated at a 700 W power setting for three cycles of 1 min. After
digestion, the vessel was cooled in an ice bath. The solutions were
filtered and diluted with water to a final volume of 50 mL. The
quantification of Pb and Cd in GFAAS was performed using the standard
additions method. The oven program employed is described in Table 1.
Determination of Mercury. The sample (0.20 g) was placed in a
high-pressure PTFE vessel. Two milliliters of 65% HNO3 and 1 mL of 35%
H2O2 were added. The vessel was sealed with the screw cap and placed
inside the microwave oven. Samples were irradiated at a 700 W power
setting for three cycles of 1 min. After digestion, the vessel was
cooled in an ice bath. The solutions, filtered and diluted with water
to a final volume of 25 mL, were left for 12 h to eliminate nitrous
vapors. The analytical conditions used for mercury determination by
continuous flow vapor generation AFS were the following: reducing
agent, 2% m/v SnCl2 in 15% v/v HCl, 4.5 mL min-1 flow rate; 5% v/v
HCl, 9 mL min-1 flow rate; carrier gas argon, 0.3 L min-1 flow rate;
sheath gas argon, 0.3 L min-1 flow rate; dryer gas, air, 2.5 L min-1
flow rate; specific Hg lamp; fixed 254 nm filter.
Results and Discussion
Methodologies. The suitability of each of the methodologies used was
checked by evaluating their analytical characteristics (limit of
detection, precision, and accuracy). Fucus sp., L. major, and U.
lactuca were used as reference materials to quantify total As, Pb, Cd,
and Hg. In the case of inorganic As there are currently no certified
materials, and therefore recovery tests were carried out on the
certified reference materials specified and on samples bought in shops
to evaluate accuracy. In the case of commercial samples, samples of
high and low inorganic arsenic contents were selected for the recovery
test. The additions carried out were in accordance with the level of
inorganic arsenic present in the samples.
The analytical characteristics of the methodologies used to determine
Pb, Cd, Hg, and As are shown in Table 2. The results obtained were
satisfactory and demonstrate that it is possible to employ these
methodologies to quantify the contaminants mentioned in commercial
samples of macroalgae. Table 3 shows the contents of total arsenic and
inorganic arsenic, lead, cadmium, and mercury in each of the samples
analyzed (mean of three independent analysis). The category to which
each of the samples belongs is also indicated, together with its
scientific and commercial names.
Total Arsenic. The contents of total arsenic found varied over a wide
range of concentrations [2.3-141 mg kg-1, dry weight (dw)]. The
highest values were found in products derived from brown algae, with
hijiki, from H. fusiforme, showing the highest results (115-141 mg
kg-1 As dw). After hijiki, the samples of F. vesiculosus (50 mg kg-1
As dw) and kombu (L. japonica: 47-53 mg kg-1 As dw) show the next
highest levels of arsenic content. The remaining products derived from
brown algae present lower contents: wakame (U. pinnatifida), 32-42 mg
kg-1 As dw; and arame (Eisenia bicyclis), 23.8-30 mg kg-1 As dw.
In general, analyses of red algae revealed total arsenic contents of
<30 mg kg-1 dw. Mention must be made of the differences observed in
the total arsenic contents found in the two types of red algae
studied. P. tenera has arsenic concentrations similar to those found
in brown algae (23.7-30 mg kg-1 dw), whereas P. palmata has far lower
values (7.56 mg kg-1 dw). The samples of green algae analyzed in this
study have the lowest contents of all the algae studied (2.3-5.17 mg
kg-1 dw).
In general it can be said that, of the products analyzed, those
derived from brown algae have higher total arsenic contents than the
products derived from red algae, results similar to those of Morita
and Shibata (13). The total arsenic contents described in the
bibliography for edible algae range between 2.0 and 172 mg kg-1 dw
(6-8, 13, 18-24), levels similar to those found in this study.
As mentioned above, Spain does not have any legislation concerning
algae food products, so that there is no legal impediment to the sale
of the products analyzed. With respect to health considerations, the
absence of data concerning the consumption of macroalgae food products
in Western countries makes it difficult to calculate intake levels,
and most estimates are based on the consumption of the population of
Japan, with a daily average consumption of brown algae of 2-3 g and a
maximum consumption of 12 g, dw (25).
Although total arsenic is not a useful parameter in the study of the
toxicological implications derived from the consumption of edible
algae, it is nevertheless still used today. Consumption of 3 g of
algae per day would give total arsenic intake for each of the samples
analyzed ranging from 7 to 423 g/day. This consumption is similar to
data obtained in studies of total diet in which intake was evaluated
on the basis of all the food consumed by the population studied
(12-345 g/day) (26, 27), which show that the highest arsenic content
is ingested by eating fish and shellfish. When a consumption of 12 g
of edible alga/day is considered, intake ranges from 29 to 1763
g/day-a higher level than that recorded in total diet studies. One may
therefore say that even if algae is a product that is not very widely
consumed by the general public, regular consumers of edible algae
would be considered as a particular group with respect to contaminant
arsenic, something that should be studied in more detail.
Inorganic Arsenic. The inorganic arsenic contents found range from
0.15 to 88 mg kg-1 dw, levels that are similar to those described by
other authors (0.030-62 mg kg-1 dw) (19, 23, 28). A high proportion of
the samples analyzed show inorganic arsenic contents of <1 mg kg-1
(0.15-0.57 mg kg-1 dw). However, products derived from the brown alga
H. fusiforme have very high contents of inorganic arsenic (83-88 mg
kg-1 dw), which constitute 60-72% of the total arsenic present in the
sample. These results coincide with the data reported in the
literature, which reveal that inorganic arsenic represents between 50
and 70% of the total arsenic in H. fusiforme (13) and between 28 and
63% in ribbon kelp (24).
The sale of edible algae is permitted in Spain regardless of its total
or inorganic arsenic content. The situation is very different in other
countries in the European Union and elsewhere in the world, where
arsenic contents are limited on the basis of the inorganic arsenic
contents. Thus, regulations in France and the United States has
maximum permissible limits of 3 mg kg-1 dw inorganic arsenic (5),
whereas in New Zealand and Australia the limit is as low as 1 mg kg-1
dw (29). These values were exceeded by the three samples of H.
fusiforme analyzed, and therefore they could not be sold in the
countries mentioned. In this respect, McSheehy and Szpunar (23) state
that algae from Brittany, China, Iceland, Japan, and Spain were
withdrawn from the French market because their inorganic arsenic
content was >3 mg kg-1 dw. The absence of legislation on this point in
Spain means that this country is likely to receive products that are
denied entrance into other markets owing to legislation.
With respect to the evaluation of risks, previous studies are rare. A
study carried out on kelp supplements (tablets, capsules, and powder)
sold in the United Kingdom (19) estimated the intake of reducible
arsenic by assuming a daily intake based on the manufacturer's
recommended maximum dose, which ranged from 4 to 14 g, according to
the product. The results showed an intake of <1 g/day in most of the
samples analyzed. However, there was one exception, with a sample of
kelp capsules in which a very high content of reducible arsenic was
found (50 g g-1). The authors (19) estimated the intake from such kelp
samples to be ~700 g/day, a level 5 times higher than the Tolerable
Daily Intake (TDI) recommended by the WHO for a body weight of 68 kg
(0.146 mg of inorganic arsenic/day) (14). Our study analyzed a wider
variety of products, and the results obtained indicate that, in order
to evaluate intake levels, the best solution is to consider two groups
of algae. With respect to algae with an inorganic arsenic content of
<1 mg kg-1 dw (84% of the samples analyzed), both the average
consumption (3 g/day) and the maximum consumption (12 g/day) give rise
to inorganic intake levels of less than the TDI. However, the
consumption of samples of H. fusiforme, with an inorganic arsenic
concentration of >80 mg kg-1 dw, would mean intake levels of between 2
(consumption of 3 g/day) and 7 times (consumption of 12 g/day) the
TDI.
The effects that continuous high intake of arsenic due to algae may
have on consumers' health have not been studied. A toxicological
evaluation carried out by Watanabe et al. (18) did not find that
arsenic produced adverse effects in rats fed with diets containing
species of Hizikia. However, the metabolic differences between species
mean that the conclusions cannot necessarily be extrapolated to
humans. Furthermore, it should be borne in mind that epidemiological
and clinical studies indicate that arsenic is a paradoxical human
carcinogen that does not easily induce cancer in animal models (30).
Because no toxicological studies are available as yet, it would seem
to be a priority to protect the consumer by carrying out a monitoring
program to establish maximum limits of inorganic arsenic content at an
international level. The advisability of withdrawing from the market
products that systematically have very high contents of the
contaminant should not be ruled out.
Lead. The products derived from the brown algae L. japonica and U.
pinnatifida had lead contents below the detection limit of the test
method used (0.05 mg kg-1 dw). In the other samples the lead content
varied between 0.15 and 1.33 mg kg-1 dw. The lowest values were found
in three samples of arame, made from the brown alga E. bicyclis
(0.15-0.19 mg kg-1 dw), whereas the highest content was found in green
nori from the green alga Enteromorpha sp. The products derived from H.
fusiforme varied more (0.53-0.89 mg kg-1 dw) than the other brown
algae products analyzed. Finally, in the products made from red algae
the lead content varied between 0.289 and 1.1 mg kg-1 dw.
The differences in lead content are not very pronounced, and it cannot
be said that particular types of algae have higher lead contents:
green algae, 0.93-1.33 mg kg-1 dw; red algae, 0.289-1.1 mg kg-1 dw;
brown algae, 0.05-0.89 mg kg-1 dw. We must remember that the
differences recorded for arsenic were as high as 100 mg kg-1 dw. The
existing data in the bibliography indicate contents that vary from
<0.01-163 mg kg-1 dw (1, 6-8, 21, 31, 32), with levels generally much
higher than those found in this study.
The lead content in the samples analyzed in this study did not exceed
the content permitted by specific legislation, such as that enacted in
France, which limits the concentration of Pb to 5 mg kg-1 dw (5). With
respect to the estimate of intake, assuming a daily consumption of 3 g
and the maximum content of the contaminant found in this study (1.3 mg
kg-1 dw), lead ingestion would be 2% of the TDI established by the WHO
(0.24 mg of lead/day for a body weight of 68 kg). If the maximum
consumption (12 g/day) is considered, the TDI would also not be
exceeded.
Cadmium. The concentrations of cadmium found in this study range
between 0.03 and 1.9 mg kg-1 dw. The lowest concentration was found in
the green algae. Two samples of wakame had the highest concentrations
in this study (1.5-1.9 mg kg-1 dw), followed by the products made from
H. fusiforme (1.0-1.46 mg kg-1 dw), E. bicyclis (0.67-0.75 mg kg-1
dw), and the sample of Atlantic dulse (0.70 mg kg-1 dw). These values
fall within the range found by other authors, 0.020-21 mg kg-1 dw (1,
6-8, 21, 32). As with arsenic levels, the contents were higher in the
brown algae tested (0.13-1.9 mg kg-1 dw) than in the red algae
(0.18-0.70 mg kg-1 dw) and green algae (0.03-0.17 mg kg-1 dw).
In 10 of the samples analyzed the Cd content was higher than the
amounts permitted by specific regulations, such as those enacted in
France, which limit the concentration of Cd to 0.5 mg kg-1 dw (5), and
14 samples exceeded the limit of 0.2 mg kg-1 dw imposed in Australia
(33).
In a worst-case scenario in terms of contaminant intake, that is, a
maximum Cd level of 1.9 mg kg-1 dw, a consumption of 3 g of this alga
would mean an ingestion of 0.006 mg/day of cadmium. This is 8% of the
amount established by the WHO (0.068 mg of cadmium/day for a body
weight of 68 kg). If consumption of 12 g/day is considered, the intake
of Cd would be 34% of the TDI, a very high percentage given that this
is the amount received from a single food product. Perhaps it would be
advisable to study the toxicological risks related to intake of Cd to
which population groups who eat substantial quantities of algae food
products are exposed, because, as they are mainly extreme edible algae
consumers, most of whom follow macrobiotic diets, they also eat large
quantities of vegetables, a food group that also makes a considerable
contribution to Cd intake.
Mercury. The algae food products analyzed have mercury levels ranging
from 4 to 42 g kg-1 dw. The lowest concentration was found in a sample
of nori (P. tenera) and the highest in a sample of arame (E.
bicyclis). The level in brown algae (12-42 g kg-1 dw) was higher than
in red algae (4-14 g kg-1 dw) and green algae (18-20.6 g kg-1 dw).
These contents are lower than those previously described (7, 21) and
do not exceed the maximum limit permitted by French regulation (0.1 mg
kg-1 dw) (5). A consumption of 3 or 12 g/day of the alga with the
highest mercury content would mean an ingestion 500 and 100 times
lower, respectively, than the TDI recommended by the WHO (0.049 mg of
mercury/day for a body weight of 68 kg).
Conclusions. A significant number of the macroalgae food products
analyzed exceed the contents of cadmium and inorganic arsenic
permitted by the few specific laws that have been enacted with respect
to these products. The high contents of inorganic arsenic found in H.
fusiforme, much higher than those of the other edible algae analyzed,
demonstrate the need to carry out a more in-depth, tailor-made study
of the toxicological implications of inorganic arsenic in algae, which
could give rise to specific restrictions on their sale. |
