How Products were Selected:Products tested represent those commonly sold and/or available nationally in the U.S. ConsumerLab.com purchased products on the open market through retail stores, on-line retailers, and direct sales companies. Products were not accepted directly from manufacturers.
- Quantitative analyses for iodine and mercury using inductively coupled plasma — mass spectroscopy (ICP- MS) or atomic absorption spectroscopy (AA).
- Quantitative analyses for lead, arsenic, and cadmium using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS).
ConsumerLab.com may modify or use other appropriate test methods if necessary to test special product formulations.
Identities of products were not disclosed to laboratories performing the testing whenever possible without affecting product integrity.
Passing Score:*To achieve a "Pass" in the testing, a product had to:
- Contain a minimum of 100% and no more than 130% of its labeled amount of elemental iodine and not exceed the Tolerable Upper Intake Level (UL) for children or adults. Tolerable Upper Intake Levels (ULs) established by the Institute of Medicine for iodine are 200 mcg for children 1 to 3 years; 300 mcg for children 4 to 8 years; 600 mcg for children 9 to 13 years; 900 mcg for teens 14 to 18 years; and 1,100 mcg for adults.
- Heavy Metals: Products must not exceed the following limits:
- Products marketed for use by children or as a snack may not exceed the State of California's Prop 65 limits for lead contamination of 0.5 mcg of lead per daily serving [above which California requires a "reproductive harm" warning due to developmental toxicity and male and female reproductive toxicity], with an additional allowance of 0.8 mcg for supplements containing more than 1,000 mg/day of calcium.
- Products with a single serving weight of less than 5 grams that are not marketed for use by children or as a snack, may not exceed the State of California's Prop 65 limits for lead of 0.5 mcg per recommended daily serving, with an additional allowance of 0.4 mcg if containing 250 to 999 mg/day of elemental calcium, potassium and magnesium or 0.8 mcg if containing 1,000 mg/day of any combination of these minerals. An additional allowance of 0.5 mcg is provided if containing 250-999 mg/day of whole herb (not extract) ingredient or 1.0 mcg for products containing 1,000 mg/day or more of whole herb (not extract). However, total lead allowance will not exceed 2 mcg per daily serving. [Note: In Canada, the limit, in a natural health product, is 10 mcg per day for an adult, but is based on body weight and would be lower for most children.]
- Products with single serving weights of 5 grams or more that are not marketed for children or as a snack may not exceed 2.5 mcg per serving nor 4.0 mcg per daily serving.
- If marketed for use by children or as a snack, may not exceed 3.0 micrograms of cadmium per recommended daily serving (based on Canada's limit for a child weighing 75 lbs.). If not marketed for use by children, may not exceed 4.1 micrograms of cadmium per recommended daily serving (above which California requires a "reproductive harm" warning due to developmental toxicity and male reproductive harm toxicity based on the State of California's Prop 65 limit).
- May not exceed 2.1 micrograms of inorganic arsenic per daily serving (Canadian limit in natural health products) and will be flagged if exceeding 10 micrograms of total arsenic (also a limit in Canada in natural health products. [Note: The Canadian limits apply to natural health products. Seaweed snacks and foods would not necessarily be considered natural health products, but ConsumerLab chooses to use these as science-based reference points. Most of the arsenic in seaweed is in the form of asenosugars, which are potentially toxic, while the inorganic arsenic is a known carcinogen.(Cherry, Nutr Rev 2019).]
- May not exceed 2 micrograms of mercury per daily serving (based on EPA limit for mercury in 1 liter of water).
- Be in compliance with FDA labeling requirements.
* Passing scores allow for specific margins of technical error associated with each analysis. ConsumerLab.com reserves the right to disqualify a product at any time from passing its testing if it considers such product to display unacceptable variation, present a safety risk or to provide misleading or inaccurate information in its labeling.
** Based on the State of California's Prop 65 law requires products exceeding this limit to bear a warning label.