Hawaiian microalgae cultivator Cyanotech analyzed dozens of leading spirulina and greens products across U.S. retail and e-commerce channels and found that nearly half initially exceeded California’s Proposition 65 limits for lead exposure. Follow-up third-party testing across multiple production lots reinforced the findings, with consistent results pointing not to isolated manufacturing issues but rather a broader supply chain problem.
When elevated lead appears consistently across multiple production lots… it points to a systemic exposure occurring upstream.
Collette Kakuk, chief strategic and chief commercial officer, Cyanotech
The results
Cyanotech conducted an initial screening of 37 top-selling spirulina and greens products, which were selected based in their “top-selling” status based on data from SPINS, Amazon sales and review volume, market visibility on Google and social listening. Subsequent third-party testing by Eurofins confirmed the presence of lead in nearly half of the samples. The company then expanded the analysis to a second phase, in which Alkemist Labs tested 19 products across multiple lots, with a greater focus on organic-labeled products.
While Cyanotech also evaluated other heavy metals internally, the company said lead emerged as the most consistent and concerning contaminant.
“Our initial screening found that 18 of the 37 products exceeded California Prop 65 lead exposure limits,” said Collette Kakuk, chief strategic and chief commercial officer, Cyanotech. “While the magnitude of the results was concerning, it was not entirely surprising,” adding that over the past few years, Cyanotech had observed an “escalating combination of offshore ‘organic’ claims, unrealistic pricing and increasing ingredient inquiries tied to clear quality issues.”
According to Kakuk, all of the high lead levels in the testing can allegedly be traced back to offshore sourcing in APAC regions, where long-term environmental stewardship of land and water resources and regulatory oversight vary significantly.
Kakuk added that price points and claims that do not align with reality raised red flags: “What was particularly concerning is that this study was comprised of top-selling products, not obscure or limited-distribution brands, that are being sold across major retail and e-commerce channels today. These are products consumers trust.”
The findings confirmed that this is not an isolated situation, she said, pointing to “a systematic, persistent and deeply concerning issue within the spirulina supply chain.”
Spirulina is complicated
Because spirulina is a bio-accumulator, it absorbs not only nutrients but also any contaminants present in the water where it is cultivated. Since it is grown in aquatic systems, the quality of that environment directly determines the ingredient’s purity.
“What makes this especially important is how spirulina is consumed. It is harvested, dried and delivered in a highly concentrated form,” Kakuk explained. “A single serving of powder represents a large amount of original biomass, so everything in it is concentrated as well, including all the beneficial nutrients–but also any contaminants present.”
With daily use often measured in grams, exposure can compound over time. Combined, these factors make the conditions spirulina is grown in a critical determinant of its safety.
The risk can be even greater in multi-ingredient greens powders, where multiple inputs from different sourcing regions introduce additional opportunities for contamination. Greater ingredient complexity can mean greater risk for exposure.
The organic issue
Increased awareness around plant-based diets, veganism and clean-label products has surged spirulina’s popularity, however, “Organic labeling alone is not a reliable indicator of environmental purity for spirulina,” Kakuk said.
According to testing conducted by Alkemist Labs, organic products did not offer better protection when compared to conventional spirulina.
Kakuk explained that USDA organic framework was developed for terrestrial, soil-based agriculture, not spirulina, which is grown in controlled aquatic systems, where water quality and environmental conditions determine its purity and safety.
“Because of this fundamental difference, the standards do not fully translate to spirulina cultivation,” she said. “In the U.S., spirulina producers cannot currently qualify for USDA organic certification under this framework. At the same time, imported ‘organic’ spirulina enters the market with organic claims obtained through international certification pathways, where standards are not always interpreted or applied consistently with USDA regulation.”
Adding to the confusion are organic seals combined with other signals that suggest safety or domestic origin. Kakuk said consumers are being misled with labels that reference U.S. packaging, distributor addresses or terms like “lab tested” or “responsibly sourced” and “pure,” with practitioner recommendations, influencer content and brand storytelling only adding to potential consumer confusion.
Price: under pressure
Producing spirulina in a controlled environment requires significant investment in water quality, environmental monitoring and cultivation infrastructure, Kakuk said, and because spirulina reflects its growing environment, these controls are essential to ingredient purity.
“At our farm in Kona, for example, spirulina is grown using potable water from deep Hawaiian aquifers, naturally filtered, protected, and continuously monitored,” she said. “In contrast, lower-cost production regions often rely on surface water sources that are more exposed to environmental contamination.”
As a result, these differences contribute to a wide price gap, with responsibly-produced spirulina often costing multiple times more than imported material.
Awareness
Asked about how widespread the awareness is among spirulina producers, Kakuk noted the scope of the work, emphasizing that the products tested were not obscure or fringe brands, but rather leading spirulina and greens products across U.S. retail and e-commerce channels purchased in significant volume.
“As one of the largest commercial spirulina producers in the United States, we have longstanding relationships across the category and have spoken with a large number of companies that formulate or market spirulina products,” she said. “We also regularly receive inbound inquiries from brands navigating sourcing and quality challenges.”
Through those interactions, Kakuk said awareness of potential contamination risks does exist, with about a third of top brands having encountered known quality inconsistencies in their spirulina supply chains.
With the hope of raising the bar across the category, Cyanotech said it has actively shared its findings to encourage more rigorous sourcing and testing practices, but the industry response remains uneven.
“With the data now public and consistent across multiple lots, that distinction is becoming much harder to overlook,” she said. “The risks are no longer theoretical—they are clearly visible in the market.”
