Maine Coast Sea Vegetables

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Testing & Purity

Radiation Testing Results and Update

March 2014

For the 2013 harvest (products to be sold mostly in 2014), we again had samples of a selection of sea vegetables tested and the results are consistent with previous years, showing only background radioactivity. To see these most recent results, click here 2013 harvest results.

Since the tsunami and nuclear catastrophe at Fukushima, Japan, in March 2011, we have had samples of nearly all of our products tested for radioactivity. This includes samples from the 2011 harvest, the 2012 harvest and the 2013 harvest. All results to date have shown only background radioactivity—no evidence of fallout from Fukushima. For example, there is a natural radioactive isotope of potassium (K-40) that is found in most if not all land and sea plants, as well as in seawater, soils, etc., and accounts for nearly all of the radioactivity observed in our seaweeds. See past results below.

Click here to see 2011 harvest results report dated June 2012

Click here to see 2012 harvest results report dated Oct 2012 and the report dated March 2013

Going forward, we plan to test samples of a selection of sea vegetables at least annually. We are grateful that we haven’t seen evidence of fallout radionuclides in our samples, and hope that trend continues.

If you’d like more information about how our samples are tested, see the letter from the UMaine lab describing methods and equipment used and details about Professor Thomas Hess, the scientist who runs the UMaine lab. Feel free to contact us at with questions.

Here are also links to resources on radioactivity we’ve found helpful:

Woods Hole Oceanographic Institution:
The ABCs of Radioactivity (plus associated links)

More resources from WHOI’s Center for Marine and Environmental Radioactivity:
About Radiation
Our Radioactive Ocean

Health Physics Society: Geiger Counters and Sea Vegetables

US Food and Drug Administration:
Derived Intervention Levels for Radionuclides (PDF file)

Information is Beautiful:
Radiation Dosage Chart

Product Testing for Possible Contaminants
Results Report for Harvest Period 2013 (Products for 2014)

Why We Test:
Although we harvest in remote areas of the Gulf of Maine, we cannot control the ocean currents. And although seaweeds have been consumed safely for centuries, we want to make sure there are no significant changes in a plant's analysis from season to season, particularly regarding trace metals.

When We Test:
Frequent and extensive microbiological testing is conducted throughout the year on a range of products, but most of our other tests are done with a sampling protocol after the harvest is completed at the end of the year. Therefore, the results in this report refer to plants/products that will be sold mostly in 2014.

What We Test:What We Test For:
  • Kelp leaf (Saccharina latissima)
  • Dulse leaf (Palmaria palmata)
  • Laver leaf (Porphyra umbilicalis)
  • Alaria leaf (Alaria esculenta)
  • Sea Lettuce leaf (Ulva lactuca)
  • Toasted nori sheets (Porphyra yezoensis)
  • Dulse powder (Palmaria palmata)
  • Kelp powder (Laminaria digitata)
  • Rockweed powder (Ascophyllum nodosum)
  • Pesticides
  • Herbicides
  • Petroleum Residues
  • PCBs
  • Heavy Metals
  • Microbiological Contaminants
  • Radioactivity (see above)

Who Does the Testing?
Our testing is performed or coordinated by Katahdin Analytical Services, Scarborough, Maine, a NELAP accredited laboratory. Our radioactivity testing is done by the University of Maine.

General Notes on Product Testing:
The seaweeds we sell are wild, uncultivated marine algae. Specific analysis may vary from the above typical analysis. Naturally occurring fluctuations in the sea plants occur due to season, weather conditions, tidal flow and time of harvest. The information presented above is believed to be accurate and reliable, but represents averages and is not guaranteed as a condition of sale. Maine Coast Sea Vegetables makes no warranty, either express or implied, and assumes no liability for this information or the products described.

We believe that traditional whole foods such as seaweeds are well suited for nourishing human cells. Worldwide, seaweed is and has been consumed with healthy results. However, we are unable to predict your body’s response. There may be elements of these plants not suitable for your particular biochemistry or condition. Only you can determine what's best for you, in consultation with your healthcare practitioner.

Please see the Table of Results for Heavy Metal Testing and Table of Results for Microbiological Contaminants below.

2013 Testing Results:
  • Pesticides (21 compounds): None detected
  • Herbicides (10 compounds): None detected
  • Petroleum Residues (17 polycyclic aromatic hydrocarbons): None detected
  • PCBs (polychlorinated biphenyls): None detected
  • Heavy Metals (see table below)
  • Microbiological Contaminants (see table below)

Table of 2013 Results for Heavy Metal Testing

PQLs (Practical Quantification Limits) for each metal are the lowest detection limits, taking into account the method, instrumentation and matrix being tested. Undetected indicates the metal was not detected above its PQL.

For more information on the presence of arsenic and other heavy metals in sea vegetables, see "Trace Elements and Heavy Metals in Maine Coast Sea Vegetables" as well as the Arsenic Update below.

Mercury (Hg)
PQL= .040 ppm
Arsenic (As)*
Cadmium (Cd)
PQL= 0.5 ppm
Lead (Pb)
PQL= 0.5 ppm
KELP whole leafUndetected*1.60 ppmUndetected
DULSE whole leafUndetected*0.7 ppm
0.7 ppm
LAVER whole leafUndetected*
3.60 ppmUndetected
ALARIA whole leafUndetected*
3.05 ppmUndetected
SEA LETTUCE whole leafUndetected*
NORI sheets (toasted)
3.79 ppmUndetected
DULSE powderUndetected*
0.643 ppmUndetected
KELP powderUndetected*
0.625 ppmUndetected
ROCKWEED  powderUndetected*
1.13 ppmUndetected


Table of 2013 Results for Microbiological Contaminants

All results preceded by a < (less than) indicate that none were detected above the given limit of detection. CFU = colony-forming unit; CFUs/g is a unit of microbial numbers in a sample.

E. coli
Aerobic Count
KELP whole leaf<2.5<2.5<2.541
DULSE whole leaf<2.5<2.5<2.5420
LAVER whole leaf<10<1033020400
ALARIA whole leaf<2.5<2.52.6
SEA LETTUCE whole leaf<2.5<2.5<2.5260
NORI sheets (toasted)
DULSE powder<10<2.57.8
KELP powder<2.5<2.5<2.577
ROCKWEED  powder<10<2.5<2.5<2.5


*ARSENIC UPDATE (February 2014):
We continue to work on identifying the most appropriate testing protocols and labs for analysis of arsenic in the sea vegetables we sell. Here are some of the variables we have discovered in our research so far:

  1. Various protocols used to determine total and inorganic arsenic in seaweeds and other samples
  2. Limited availability of methods appropriate for the unique nature of seaweeds, and experience with seaweeds among labs
  3. Various methods for arsenic speciation (determining the different kinds of arsenic, organic and inorganic)
  4. Differing results depending on harvest seasonality, species of seaweed, annual or perennial growth, etc.
  5. Few of the seaweeds studied so far are species we harvest, making it difficult to extrapolate
  6. Incomplete information about how different forms of arsenic are metabolized
  7. Several models used to assess bioavailability, and within these, many variables including: pH, temperature, time, agitation, enzymes and acids, gut microbes




Trace Elements and Heavy Metals in Maine Coast Sea Vegetables

The presence of certain elements in sea vegetables causes alarm to some consumers. The following information addresses those fears. Critical to evaluating this question are 1) what form are these elements in, 2) the amounts, and 3) the historical or epidemiological evidence. Because sea vegetables are as low on the scientific research priority list as they are on the food chain, we have to infer in part from studies of other food groups, as well as use our native intelligence and intuition.

Sea vegetables contain a wide array of major minerals and trace elements, including lead, cadmium, arsenic, aluminum, zinc, chromium and many more. Small quantities in the right "organic" form are proven or estimated to be essential to human health. In the straight "inorganic" form and in excessive quantity, they can be toxic. Let's look at arsenic as an example.

Arsenic occurs in two basic forms, inorganic and organic. Inorganic arsenic occurs naturally (20th most abundant element in the earth's crust), and is found in pesticides, paint, and a host of manufactured chemical compounds. Inorganic arsenic is known to be toxic, causing skin lesions, organ damage, and promoting tumor growth, and, in acute overdose, is fatal.

Organic arsenic is presumed to be found in all living organisms. Vegetation absorbs the mineral from the soil (or in the case of sea vegetables, from the ocean) and transforms it into one of many forms of organic or colloidal arsenic. When creatures higher on the food chain eat these plants, this organic arsenic is further processed ("methylated") by the liver into further non-toxic forms, most of which is excreted through the urine. It is only when inorganic arsenic enters the body and lodges in organ tissue that toxic symptoms are observed. Though research is on-going, chronic toxicity from organic arsenic is unlikely, even in the instance of high shellfish consumption, where arsenic levels are briefly but dramatically elevated before being excreted.1

On the other hand, recent studies suggest that low levels of arsenic in human blood serum are correlated with central nervous disorders, vascular disease, and cancer. Animal studies have shown organic arsenic to be essential to heart and skeletal muscle function in goats, and beneficial in small amounts to a variety of laboratory animals. Recent work indicates that arsenic may have a role in methionine metabolism. Therefore, it is plausible to suggest that humans have an essential need for arsenic, at a computed requirement of 12 to 50µg (micrograms) per day.

Scientists looking at Japanese sea vegetables and consumption habits concluded that eating seaweed provided on average about 100 to 150µg arsenosugar (a form of organic arsenic) per day.2 Even with this high intake, there are no reports that the Japanese population demonstrates chronic symptoms of arsenic toxicity due to sea vegetables.

Furthermore, the World Health Organization (WHO) Tolerable Weekly Intake for inorganic arsenic (As) is 50µg per kg of adult bodyweight.3 This would mean that someone weighing 150 lbs could tolerate up to 3409µg of inorganic As per week or 487µg per day. So hypothetically, if a seaweed tested at 3µg/g or ppm of inorganic As, one would have to eat 162g or almost 6 oz daily to exceed this WHO limit. Even the Japanese average much less than this. We believe it's a reasonable conclusion that normal seaweed consumption does not pose a risk in terms of arsenic.

The same sort of reasoning applies to the other metals. They occur naturally; they are taken up and transformed by land or sea vegetation, and are utilized or excreted as needed by mammals and other animals. For example, aluminum is a very abundant metallic element, about 12% of the earth's crust and in the organic form is commonly found in vegetation. Beans contain 20-250 ppm, peppers and peanuts contain 50-200 ppm, corn and wheat contain 20-300 ppm. We can eat these without toxic consequences because metallic aluminum has been transformed by the plants' metabolic process into its non-toxic organic, colloidal form. It's even logical to suspect that our bodies, which evolved from the earth's elements, might have a use for this very common element in its organic form. Inorganic aluminum, however, is known to be toxic, and is implicated in Alzheimer's and breast cancer.

In 1989, a conversation with Dr. Ernest Foulkes, heavy metal researcher at the University of McGill in Montreal, focused on whether the bound organic metallic compounds in the human stomach (pH 1) are broken down at all - and, if so, how they may recombine in the small intestine (pH 6) with hundreds of chelating substances (proteins, amino acids, bile salts, complex carbohydrates) and pass harmlessly through the gut - just as studies show how arsenosugars are excreted in the urine after ingestion of arsenic in seafood.4

As there's much yet to learn, we recommend that you consult a healthcare professional if you have any questions about your intake of heavy metals. (Dietary deficiencies and genetic variability, for instance, can effect how well an individual's metabolism changes arsenic to more organic forms, with implications for tissue distribution and toxicity.5 Furthermore, vocational or environmental exposure may impact one's body load of metals and effect metabolic capacities.)

Please refer to our annual "Statement of Product Testing" at the top of this page, for specific amounts of certain trace metals in our sea vegetables.


  1. Speciation of Six Arsenic Compounds in Korean Seafood Samples by HPLC-ICP-MS, Kyung Su Park et al, Ky Engineering Materials, Vols. 277-279 (2005) pp.431-437
  2. Study of in vitro cytotoxicity of a water soluble organic arsenic compound, arsenosugar, in seaweed, Sakurai et al, Toxicology, 122 (1997) 205-212
  3. WHO Tolerable Weekly Intakes for other inorganic elements: CD (cadmium) 7µg/kg adult weight; Hg (mercury) 5µg/kg adult weight; Pb (lead) 50µg/kg adult weight
  4. Organoarsenical Species Contents in Fresh and Processed Seafood Products, M. Angeles Suner et al, J. Agric. Food Chem, 2002, 50, 924-932
  5. FDA website: Center for Food Safety and Applied Nutrition (re: arsenic & shellfish)




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