Heavy metal limits on a supplement label are written in ppm, and 1 ppm means 1 microgram of a metal in every gram of finished product. That is a concentration, not a dose, and what you actually swallow depends on how many grams you swallow. Two bottles can print the same ppm and deliver different amounts.
How heavy metal limits are written
ppm is parts per million, and a lab report often prints the same result as mg/kg, since a kilogram holds a million milligrams. Either way the reading is the same.
Some reports use ppb for contaminants that get watched closely. A ppb is one thousandth of a ppm, and labs switch to it when the ppm value would otherwise be a long run of zeros after a decimal point. Units are not doses. Neither one says anything about exposure until you have a weight to apply it to.
Turning ppm into micrograms per serving
A concentration becomes a dose only when you know the serving mass. Take a 500 mg serving, which is half a gram. At 1 ppm that serving carries 0.5 mcg of the metal in question, and at 0.5 ppm it carries 0.25 mcg. The arithmetic is the entire point of the unit.
Here is where labels stop helping. Plenty of bottles state the serving in milligrams of an extract or a blend and never print the gram weight of the finished gummy or capsule. You can still do the conversion, but you are supplying the serving mass yourself. Say that out loud when you do it, rather than presenting the result as if the label had printed it.
Why organ ingredients get the closer look
Liver and kidney are the organs that filter and store what an animal takes in, so beef liver and beef kidney are the raw materials where a testing line carries the most weight. That is a property of the tissue, not a judgment about one bottle.
The grass fed beef liver gummies list naturally occurring vitamin A, B12 and iron, all of them tied to the liver itself. The desiccated beef liver bottle states 60 gummies at 2 per day for a 30 day supply, and the second half of that sentence is the part shoppers skip: a per serving limit gets multiplied by 2 every day, and by 60 across the bottle. Daily total is the number that almost never gets calculated.
What a third-party COA covers
Third party means a laboratory that does not work for the seller ran the assay. The report should carry the lab name, a batch or lot number, the method used, and a result measured against a stated limit. A page that says tested, with no lot number anywhere on it, is a claim rather than a document.
The coverage is also narrow. A heavy metals panel usually covers lead, arsenic, cadmium and mercury, and it says nothing about potency, nothing about microbial counts, and nothing about whether the contents match the label. Those are separate lines that live on separate reports.
GMP certification is a third thing again. It speaks to how a facility is run, not to what any single batch measured, and the two get conflated constantly on product pages.
Where California Prop 65 fits
California maintains a public framework of limits for listed chemicals, and Prop 65 is the name most American shoppers recognise. The list, the way a limit is set for a given chemical, and the point at which a warning becomes necessary all work in their own way, and they change over time. I won't quote a section number here, because a section number pulled out of context is worse than no number at all.
What is safe to say is narrower than most people assume. A Prop 65 warning is notice about exposure to a listed chemical under that state's rules. It is not a statement that a product broke a federal limit, and a bottle can sit on one side of one line and the other side of the other.
Reading the numbers before you buy
Work in a fixed order. Find the gram weight of a serving. Multiply by the ppm figure to get micrograms per serving. Multiply again by the number of servings you take in a day. If step one is missing, count everything after it as an estimate and write it down as one.
The beef kidney gummies put 500 mg of bovine kidney into a 2 gummy serving as a 5:1 extract, and the label doesn't say whether that 500 mg is the weight of the extract or of the tissue it was concentrated from. The ambiguity bites twice, once for how much kidney you are getting and once for which mass a ppm result would be calculated against. That same listing sits in the digestive health collection, because kidney tissue is the source usually named when DAO comes up.
Across the wider beef liver supplement range and the general adult supplement shelves, a batch number should be available on request. If a seller can't produce one for the lot you are holding, that answer is itself information.
Are heavy metal limits the same in every state?
No. Federal limits for supplements are set one way, California's Prop 65 runs as a separate warning framework, and most bottles print neither number. Ask the seller for the batch report instead.
Does third-party tested mean zero heavy metals?
No. It means a lab measured that batch against a stated limit, and most natural ingredients return a small nonzero result. What matters is where the number falls relative to the limit.
How do I turn ppm into something I can compare?
Multiply the ppm figure by the serving weight in grams, and the answer is micrograms per serving. Multiply once more by servings per day to get your daily figure.