Why We Chose It
The Bonham Conclusion
We chose Frontier Co-op Baking Soda because it holds the strongest purity specification available for a consumer baking soda product — USP Grade #1, the United States Pharmacopeia's highest commercial purity standard — sourced from naturally mined nahcolite with no chemical synthesis, no additives, and never treated with ethylene oxide or irradiation.
We want to be fully transparent about what we do not know: no US baking soda brand currently has published independent third-party heavy metals testing with non-detect results from Lead Safe Mama, Mamavation, or any comparable independent program. This category has not been independently tested the way salt, flour, or rice has been. That is reflected in the Verified score. Within the constraints of what is currently verifiable, Frontier Co-op's USP Grade #1 specification is the strongest quality claim available — and their 50-year track record as a member-owned cooperative with documented commitments to purity gives us confidence in what they say about their product.
Who They Are
Frontier Co-op — 50 Years as a Member-Owned Cooperative
Frontier Co-op has been a member-owned cooperative since 1976 — nearly 50 years of operation owned by the stores and organizations that buy and sell their products. That structure matters. A cooperative's financial incentives are fundamentally different from a conventional brand's. The members own it and hold it accountable.
Their standing commitment across their entire product line is that products are never irradiated and never treated with ethylene oxide — a chemical sterilant that has been found as a contaminant in some supplement and spice products in recent years. This is not a label claim on a single product. It is a documented company-wide policy.
Their baking soda is sourced from naturally mined nahcolite — sodium bicarbonate in its natural mineral state, extracted from underground deposits using a hot water solution process with no chemical alteration. The same Colorado nahcolite deposits that supply Frontier also supply USP pharmaceutical-grade sodium bicarbonate to the medical and pharmaceutical industries. The raw material source is among the purest natural sodium bicarbonate deposits in the world.
Claims & Certifications
What Frontier Co-op Claims — And What Each One Means
Independent Research & Lab Testing
What We Know — And What We Don't
Honest transparency note: No published independent third-party heavy metals testing results are publicly available for Frontier Co-op Baking Soda. The entire US baking soda category has not been independently tested for lead, cadmium, mercury, and arsenic by Lead Safe Mama, Mamavation, or comparable investigators as of May 2026. We evaluated every option available and found no brand in this category with published non-detect results. This is reflected in the Verified score on the product page.
USP Grade #1 is a meaningful specification. The United States Pharmacopeia sets limits for arsenic, heavy metals, and other impurities in sodium bicarbonate as part of the USP monograph. Meeting USP Grade #1 means the product has been tested against those limits — but individual results by specific metal are not published publicly for consumer products. The full USP monograph for sodium bicarbonate is publicly available at usp.org.
Frontier Co-op's sourcing from Colorado nahcolite deposits is relevant context. Natural Soda LLC — the primary producer of nahcolite sodium bicarbonate in North America — holds USP Grade, USDA Organic certified, Non-GMO Project Verified, Halal, and Kosher certifications for their raw material. The Piceance Creek Basin deposit in northwestern Colorado is considered among the purest natural sodium bicarbonate deposits in the world, with over 5 billion tons of high-purity nahcolite reserves.
We review published certifications and available documentation. We are not a laboratory and do not conduct our own testing. If independent heavy metals testing results become available for this product category, we will update this evaluation accordingly.
The Broader Picture
Why Baking Soda Source and Manufacturing Standard Matter
Most baking soda on the market is produced through chemical synthesis — trona ore is mined, heated into soda ash, then reacted with carbon dioxide and water. This is not inherently dangerous, but it is industrial chemical processing rather than natural mineral extraction.
Naturally mined nahcolite skips chemical conversion entirely. The sodium bicarbonate already exists in its final form underground. Hot water dissolves it, brings it to the surface, and recrystallization produces the finished product. No chemical reactions required.
The ethylene oxide issue is worth understanding in context. ETO has been found as a contaminant in sesame seeds, spices, and some supplement products — it can remain as a residue after treatment and has been classified as a human carcinogen by the International Agency for Research on Cancer. Frontier Co-op's policy of never using ETO or irradiation across their entire product line directly addresses this risk.
The USP Grade specification is also worth understanding fully. Food-grade sodium bicarbonate must meet basic purity standards. USP Grade #1 requires meeting pharmaceutical-grade purity thresholds — the same standard used for sodium bicarbonate in medical applications. It is a meaningfully higher bar.
"USP Grade #1 is the same purity standard required for sodium bicarbonate used in intravenous medical solutions. It is the highest commercial purity specification available — and it is the standard Frontier Co-op's baking soda meets."
