Aflatoxin Group (B1, B2, G1, G2): What the Number on a Urine Mycotoxin Panel Means

At a Glance

This line is not one substance. Aflatoxins are a family, and the panel reports four of them together as one group result in parts per billion.

They come from crops: "a family of toxins produced by certain fungi that are found on agricultural crops such as maize (corn), peanuts, cottonseed, and tree nuts." Diet is the main source for the general population, while significant airborne exposure is described in industrial and agricultural work.

That matters for reading a urine result. This is a single spot sample, so the figure describes one moment. How much an exposure shows up in urine, and for how long, the panel's documentation does not establish.

The range printed beside your result is the laboratory's own reporting cutoff, not a health threshold. A 2024 review by the Navy and Marine Corps Force Health Protection Command states plainly that "no urine mycotoxin reference ranges have been established" and that "there is no FDA-approved test for mycotoxins in human urine."

The practical meaning is narrow: which of the laboratory's three reporting categories your spot sample fell into.

What the panel measures, and how

The RealTime Laboratories panel "screens for 16 mycotoxins using competitive ELISA" from a urine sample. "Results are reported in parts-per-billion (ppb)" and indicate "whether each toxin was present, not present, or equivocal."

Two features of that design shape what your result can say.

It is a group result. B1, B2, G1 and G2 are reported together as one figure, so the report does not give a separate value for each. The documentation does not describe how the group concentration is derived, so the number should not be read as a breakdown of which member was present.

It is an antibody method, not a separation method. A competitive ELISA detects what its antibody binds, which is a different kind of measurement from one that separates and identifies each compound individually.

Where the number beside your result comes from

A reference interval is built by measuring a population and describing where its values fall. No such interval exists here: "no urine mycotoxin reference ranges have been established."

What the laboratory publishes instead is three categories, and its sample report sets them for the aflatoxin group as:

There is a band where the laboratory declines to call the result either way, so 0.9 is not the same finding as 2. Each toxin on the panel has its own thresholds: ochratoxin A is called present at 2 ppb or above, zearalenone at 0.7, the trichothecene group at 0.09.

The same word on two mycotoxin panels is therefore not the same finding — the aflatoxin pages on this site carry thresholds from three laboratories in two different units.

What a urine aflatoxin result reflects

Something that got into the body — with diet the main route for people not exposed at work.

The Navy review is direct about the inference the test invites, and it scopes the claim: "Except in such acute poisonings, mycotoxin tests reflect ingestion (food contamination) rather than inhalation." It lists ordinary dietary sources — "fruits, vegetables, cheese, or grain products with mold growth, and drinking coffee or wines." On routes generally it is precise: adverse exposure "generally occurs only by ingestion (e.g., aflatoxin in peanuts or heavily contaminated foodstuffs) or with significant airborne exposures in industrial (e.g., waste processing) or agricultural settings (e.g., grain silos)."

Aflatoxin M1 specifically is a metabolite that appears in milk, and it is produced when the liver processes the parent compounds.

This is the part worth sitting with if the test was ordered because of a building. A urine aflatoxin does not trace the toxin to its source, and a home is neither setting where significant airborne exposure is described. What the sources do not establish is how much an ordinary diet should put in a urine sample, so the result cannot tell you whether your value is the expected consequence of eating normally.

How to read your result

Read this against the category printed on your own report.

No row here is a diagnosis, and no row identifies a source.

If you remember only one thing

The thresholds beside your result were set by the laboratory, not established from a population — and there are three of them, not one, with a band in the middle the laboratory declines to call.

That limits what a single spot sample can carry. Take it to the clinician who ordered it, with what you have been eating and any symptoms, and ask what it changes.

Two people, same result

Two people both have an aflatoxin group result reported as Present on the same panel.

The first eats peanut butter in the mornings and corn products through the week. Diet is an important source, so that is a plausible route — though the assay cannot establish whether an ordinary diet accounts for this value.

The second had the test run after finding mold in a basement and feeling unwell. The number does not distinguish the two. It measures what reached the urine, not where it came from.

Same figure, same panel, and no cause identified either way.

What this result cannot tell you

Where the aflatoxin came from. A urine result carries no information about source.

Whether a building made you ill. This is the inference the test is sold to support — RealTime describes it as measuring "your exposure to mold toxins that standard blood tests miss" — and the evidence does not carry it. The AAAAI and the Institute of Medicine "have concluded that the evidence does not support the position that mycotoxin-mediated disease (mycotoxicosis) occurs through inhalation in non-occupational settings", and the CDC "does not recommend biologic testing of persons who work or live in water-damaged buildings."

Which aflatoxin was detected. The result is a group figure.

How much exposure you have had over time. This is one spot sample; the literature uses the serum aflatoxin-albumin adduct for that question.

Whether your symptoms are explained. Nothing about this number speaks to symptoms.

How your result compares with someone else's. Different laboratories use different methods, units and cutoffs.

Common interpretation mistakes

Reading the thresholds as a reference range. None has been established; they are the laboratory's own.

Reading a detection as a diagnosis. Detecting a compound above a reporting level establishes that it was detected.

Treating the result as evidence about a building. The test measures urine, and outside rare acute poisonings the Navy review states that mycotoxin tests reflect ingestion rather than inhalation.

Comparing a result to another laboratory's. Two panels can use different methods, units and thresholds for the same name.

Reading the group number as one substance. Four are reported together.

Assuming a Not Present result clears anything. It is one sample.

Questions your doctor may ask

What have you been eating — corn products, peanuts, tree nuts, dried fruit?

Who ordered this panel, and what question was it meant to answer?

What symptoms are you having, when did they start, and what makes them better or worse?

Have your liver enzymes been checked, and do you have any known liver condition?

Have you started any supplements or treatments because of this result?

Has anyone else in your household been tested or become unwell?

Read together with

Ochratoxin, Zearalenone, Trichothecene Group and Gliotoxin — the other toxins on the same panel, each with its own thresholds.

Aflatoxin M1 — the metabolite that also appears in milk, reported separately on some panels.

ALT, AST, GGT, Alkaline Phosphatase, Bilirubin and Albumin — liver chemistry that helps assess liver injury and function, and that this panel does not measure.

Alpha-fetoprotein — ordered in liver-cancer surveillance for people who already have a known risk, not as a response to a mycotoxin panel.

Clinical pearls

There is no LOINC code for this result. Codes exist for individual aflatoxins in animal tissue and feed; none covers a grouped aflatoxin in human urine.

The long-term exposure question is answered with a different specimen. The aflatoxin-albumin adduct in serum is the biomarker the literature uses for exposure over extended periods.

Aflatoxin exposure at population scale is a real food-supply concern. The National Cancer Institute notes that "exposure to aflatoxins is associated with an increased risk of liver cancer", while recording that "no outbreak of human illness caused by aflatoxins has been reported in the United States, but such outbreaks have occurred in some developing countries." US food is monitored: the FDA "tests foods that may contain aflatoxins, such as peanuts and peanut butter."

The Navy review notes a specific harm from acting on unvalidated results: they "can lead to misinformation, fear, and unnecessary or inappropriate medical interventions."

Clinical Takeaway

The aflatoxin group line reports B1, B2, G1 and G2 together as one result in parts per billion, from a competitive ELISA on a single spot urine sample. Three properties of that design limit interpretation: it is a group figure giving no separate value per constituent; the specimen is one point in time, with no exposure window established for the assay; and the thresholds are the laboratory's own, because no urine mycotoxin reference ranges have been established and no FDA-approved test for mycotoxins in human urine exists. The sample report sets three categories rather than one boundary — Not Present under 0.8 ppb, Equivocal 0.8 to under 1, Present at 1 or above — so an equivocal value is not a positive. Diet is the main source for people not exposed at work, with significant airborne exposure described in industrial and agricultural settings, and, outside rare acute poisonings, the Navy review states that mycotoxin tests reflect ingestion rather than inhalation — so a result does not attribute exposure to a building. The AAAAI and the Institute of Medicine have concluded the evidence does not support mycotoxin-mediated disease through inhalation in non-occupational settings; the CDC separately does not recommend biologic testing of people who work or live in water-damaged buildings. Aflatoxin exposure is a genuine food-safety concern associated with liver cancer at population scale, monitored in the United States food supply. A result the laboratory reports as Present is a measurement, not a diagnosis, and belongs with the clinician who ordered it alongside diet, symptoms and liver chemistry.

In one sentence

This line reports four aflatoxins together as one group result from a single urine sample, sorted into three categories the laboratory defined, because no reference range for mycotoxins in urine exists.

Bottom line

Your report shows four aflatoxins reported together as one number. They come from fungi on crops — corn, peanuts, tree nuts, cottonseed — and diet is the main source for people who do not work around grain or waste processing.

The figures beside your result are the laboratory's own categories: Not Present under 0.8 ppb, Equivocal from 0.8 to under 1, Present at 1 or above. No reference range for mycotoxins in urine exists and no FDA-approved test for them exists, so those are the laboratory's decisions rather than validated health thresholds. An equivocal value is the laboratory declining to call it, not a positive.

This is one spot sample. It does not say which of the four was found, how much exposure you have had over time, or where it came from — and it cannot connect a result to a building. It also cannot tell you whether ordinary eating explains your value; nothing in the documentation maps diet onto these thresholds.

If the panel was ordered because you are unwell, the symptoms are still worth taking seriously — this number just is not the thing that explains them. Take the report to the clinician who ordered it, with what you have been eating, your symptoms and your liver enzymes, and ask what it changes before starting anything on the strength of it.