Lead is a naturally occurring heavy metal in the Earth’s crust, but it is not naturally present in high concentrations in clean food or water. Most problematic lead exposure results from human activity — contaminated water infrastructure, industrial runoff, and poor agricultural practices. It is a toxic heavy metal with no safe exposure level for humans. Chronic ingestion, even in trace amounts, is linked to neurological damage, developmental issues in children, cardiovascular disease, and kidney damage.

Concerns over lead exposure led to the passage of California’s Prop 65, which mandates that any product exposing consumers to more than 0.5 micrograms (mcg) of lead per day must carry a clear warning label.

While California’s Prop 65 is often criticized for being too strict, national standards reflect similar concerns about lead exposure in supplements. Per the NSF/ANSI 173 Standard for 2024, lead content in finished dietary supplement products must not exceed 0.01 mg (10 mcg) per daily dose (Section 5.3.1.2).

Trace levels of heavy metals like lead can be found in soil, water, and even foods like avocados or spinach. A whole avocado grown in healthy soil might contain less than 0.01 mcg of lead — far below health thresholds. But spirulina and greens powders are not whole foods; they are ultra-dense, dehydrated, and concentrated with greens often containing dozens of plant-based ingredients.

A single scoop may represent the equivalent of several pounds of raw material. If those ingredients were grown in contaminated soil or poor-quality water, the concentration effect amplifies the problem — turning “trace” into “toxic.”

Exposing a Problem

Internal audits by Cyanotech over the past three years, corroborated by third-party laboratories, expose a far-reaching industry problem: low-cost, offshore-sourced spirulina and greens products with questionable purity, misleading organic claims, and mounting risks to consumer trust and public health.

Cyanotech undertook an ambitious testing protocol; we systematically procured and analyzed best-selling, conventional and organic-labeled spirulina and mixed greens products containing spirulina from online marketplaces such as Amazon.com and brick-and-mortar retail channels, utilizing both internal and third-party laboratories. Testing focused primarily on heavy metal contamination, with a particular focus on lead.

Between July 2024 and November 2024, Cyanotech systematically procured 37 best-selling spirulina and greens powder products sold to U.S. consumers through Amazon and major national retailers per SPINS natural channel data. All lead analysis was performed via Inductively Coupled Plasma Mass Spectrometry (ICP-MS), following AOAC-approved methods. Importantly, Prop 65 lead limits were scaled to each product’s serving size or recommended daily dosage to accurately reflect real-world consumer exposure.

In internal testing, more than one-third of the spirulina products (8) exceeded California Prop 65 limits for lead, including nearly half (6 of 14) of all organic spirulina products tested. Further, 10 greens powders exceeded Prop 65 limits, including more than half (8 of 13) of organic mixed greens powders, and 2 of 3 conventional greens powders.

Following internal heavy metals testing, new, unopened products from all failing brands were tested by Eurofins, an ISO-certified third-party laboratory, which confirmed every high-lead finding.

Ongoing Quality Issues

Starting in 2025, we conducted third-party validation through Alkemist Labs, another ISO-certified third-party lab, to test new unopened bottles across three distinct lots per product whenever possible.

A total of 19 products were tested by Alkemist Labs, including all 6 organic spirulina products that failed internal lead testing plus one new trending brand (7 total), and all 10 mixed greens powder products that failed lead testing plus two more trending mixed greens powders (12 total).

The testing by Alkemist Labs confirmed all (7 organic spirulina products and 12 mixed greens products) exceeded Prop 65 limits. In addition, the vast majority provided no visible Prop 65 warning to consumers.

• Spirulina Products: 4 of 7 spirulina brands failed to provide any Prop 65 warning, despite exceeding limits by 1.5x to 6x; all failing brands were linked to offshore spirulina sourcing.
• Mixed Greens Products: 10 of 12 mixed greens brands failed to provide any Prop 65 warning, despite exceeding limits by 1.4x to 9.2x; origin of many of the ingredients in these blends is difficult to confirm.

Consumers buy spirulina and greens powders to enhance health, not gamble with it. Spirulina is one of the world’s most nutrient-dense and sustainable superfoods. But low-cost, offshore-sourced spirulina has become a growing problem in the global supply chain—without the transparency or purity consumers deserve.

At our farm in Kona, Hawaii, we lead with high standards, rigorous testing, transparency, and integrity because consumers deserve better, and the future of our category demands it. Our Hawaiian Spirulina is cultivated in one of the world’s cleanest environments, with potable aquifer water and tight control over every input. We test every lot for heavy metals and deliver well below limits, because protecting consumer health isn’t a marketing message, it’s our mission.

About the Author: Collette Kakuk is Chief Strategic & Commercial Officer at Cyanotech Corporation / Nutrex Hawaii, where she leads global marketing, strategy, and ingredient business development for Hawaiian Spirulina and BioAstin Hawaiian Astaxanthin. With over 25 years of experience in branding, marketing, and business development across the natural ingredients, food, and wellness industries, she is a strong advocate for truth in marketing, transparency, and U.S.-grown solutions. Her passion lies in making things better for people, animals, and the planet. A proud U.S. military veteran, Collette also holds an MBA from the University of Michigan’s Ross School of Business.