← Back to Stage 1 · The Window
STAGE 2 The Frame · the math the journey runs on
Parts per billion is a chemistry unit. Dose is what crosses to your kid.
Two multiplications. That's the whole skill. Once you can convert ppb to micrograms-per-day in your head, every label in stages 3 and 4 of this journey reads itself. This is the page everything else uses.
2.2 µg
FDA child IRL · per day
8.8 µg
FDA adult IRL · per day
5×
kids absorb more lead per bite
µg/day Pb · what reaches a developing brain
The two multiplications.
Take two numbers off the label or the lab report: how many grams in a serving, and how many parts-per-billion of lead in the food. Multiply. Divide by a thousand. That's the daily dose in micrograms. Then compare to the FDA's daily reference. Done.
µg/day = grams_per_serving × ppb ÷ 1,000
1. Grab the ppb from the lab report or a label.
2. Multiply by the serving size in grams.
3. Divide by 1,000.
4. Compare to 2.2 µg/day (child) or 8.8 µg/day (adult).
If the result is more than 5% of either reference, the label is hiding something the dose math is not.
FDA Child IRL
2.2 µg/day
Daily lead intake from food and drink that, under the FDA's Interim Reference Level framework, is below the threshold of measurable population-level harm. Children under 7. Not weight-based.
FDA Adult IRL
8.8 µg/day
Same framework, women of childbearing age. Pregnant women's lead crosses the placenta. The reference is set at the level above which fetal blood lead becomes measurable.
4×
Kid IRL is 4× lower because gut absorption is 4–5× higher
Try the conversion right now.
Type any serving size and any ppb number from a label. Watch the dose update. Tap a preset to see the worked examples without doing the math yourself.
grams × ppb ÷ 1,000 × servings
0.13 µg/day
5.9% of FDA reference
Watch · daily use is borderline
Try a real product →
The conversion in action.
Same two multiplications, four products from elsewhere in this journey. Click through to the proof page for each one.
Stage 1 · Baby toothpaste
250 mg blob of Colgate Baby Toothpaste, twice a day
0.25 g × 257 ppb = 64 ng/brushing
× 2 brushings = 0.13 µg/day
× 2 brushings = 0.13 µg/day
≈6%of FDA child IRL · per day
→ See it on Stage 1 / The Window
Stage 3B · Infant formula
122 g/day of Bobbie Whole Milk Formula
122 g × 0 ppb = 0 µg/day
The cleanest brand in the dataset.
The cleanest brand in the dataset.
0%of FDA child IRL · per day
→ See the 38-formula sortable table
Stage 3A · Prenatal · Lactation tea
28 g cup of Mother's Milk Lactation Tea
28 g × 160 ppb = 4.48 µg/cup
One cup, once a day.
One cup, once a day.
51%of FDA adult IRL · per cup
→ See Track A · Prenatal Supplement Truth
Stage 3A · Wellness supplement
30 g daily serving of Bryan Johnson Supplement
30 g × 388 ppb = 11.6 µg/day
Per the labeled serving.
Per the labeled serving.
132%of FDA adult IRL · before food, water, dust
→ See Track A · Prenatal Supplement Truth
Want every food in one shot?
The full database is over here.
The calc above is one food at a time. bloodleadcalculator.com has every food in the FDA Total Diet Study. Build your whole day, add non-food exposure, watch your dose move against the FDA reference.
Open the full database →
What "% of IRL" actually means when you're standing in the aisle.
A single number can sound abstract until you know what to do with it. Here's how to read the percentage you compute, in four bands. Use them on every label.
< 5%
Acceptable
Daily use is fine. The dose your kid is getting from this product, in isolation, is small. Stack it with the rest of their day.
5–15%
Watch
Notable. Daily use is borderline; rare or occasional is OK. If you have a cleaner alternative, switch.
15–50%
High
Daily use should stop. One product shouldn't deliver this much of the daily reference on its own. Switch brands, switch type, or eliminate.
> 50%
Critical
Stop. Audit the rest of the diet for stacking. This single product is consuming the FDA daily reference budget your kid has for everything else. Get a blood lead test for the kid if there's been ongoing exposure.
Small daily doses × 6 years = permanent IQ math.
The 0–6 brain-development window doesn't reset. Lead doesn't pass through. It binds to bones, crosses the blood-brain barrier, and disrupts the synapse pruning that's actively happening in those years. A 5%-of-IRL daily dose looks small in isolation. Multiplied by 365 days × 6 years, it's a meaningful body burden. The dose math is daily; the consequences are lifetime.
This is the case for stacking the brand-named, dose-converted view of every label. A single small-dose source isn't worth panicking about. Several stacking small-dose sources, every day, for the entire window your child's brain is being built — that's the picture this whole journey is pointing at.
110 µg
Toothpaste alone · 6 yrs
+ ~48 µg
Tap water · pre-1986 home
+ ~70 µg
Snacks & baby food · 6 yrs
+ ?
Paint dust · environmental
FAQ.
What does ppb mean in food safety testing?
PPB (parts per billion) measures the concentration of a metal in food — how many micrograms per kilogram of food. It does not tell you the dose your child actually consumes per day. To get the dose: multiply grams_per_serving × ppb ÷ 1,000 = µg/day. Then compare to the FDA Interim Reference Level for the audience eating it.
What is the FDA Interim Reference Level for lead in children?
The FDA Interim Reference Level (IRL) for dietary lead is 2.2 µg/day for children under 7 and 8.8 µg/day for women of childbearing age. These are not legal limits — they are the daily intakes above which population-level blood-lead increases become measurable. The child IRL is 4× lower than the adult IRL because children's gastrointestinal absorption is roughly 5× higher.
Why does body weight matter for cadmium, arsenic, and mercury but not lead?
Cadmium (ATSDR MRL 0.1 µg/kg/day), arsenic (EPA RfD 0.3 µg/kg/day), and mercury (EPA RfD 0.1 µg/kg/day) use weight-based reference levels because their toxicity scales with body burden relative to body size. Lead's reference level is biology-based rather than weight-based because children absorb 4–5× more lead from food than adults regardless of size — the 4× kid/adult IRL ratio bakes that absorption multiplier in.
Why does this page use 2.2 µg/day instead of 3 µg/day for the child IRL?
Different FDA documents have used slightly different values over the years; 2.2 µg/day is the most widely cited current FDA Interim Reference Level for children, and is the value used across the rest of the DetectLead journey for consistency. The 3 µg/day figure appears in some older guidance documents. The methodology is the same; the threshold is calibrated slightly differently.
Is cadmium in food dangerous?
Yes. Cadmium accumulates in the kidney cortex with a biological half-life of 10–30 years and causes tubular dysfunction that worsens silently over decades. The ATSDR Minimal Risk Level is 0.1 µg/kg/day. For a 20 kg child this means a ceiling of 2 µg/day; for a 70 kg adult, 7 µg/day. The primary danger from dietary cadmium is kidney disease, not cancer, though cadmium is an IARC Group 1 carcinogen.
How many Americans are on dialysis for kidney disease?
Approximately 808,000 Americans are currently on dialysis. 37 million Americans have chronic kidney disease. Cadmium is a recognized dietary nephrotoxin that accumulates in the kidney cortex and contributes to tubular dysfunction that can precede kidney failure by decades.
You finished Stage 2. Three proof tracks ahead.
Now apply this conversion to the things in your house. Pick a track based on where you are: trying to conceive (3A), feeding a baby (3B), feeding solids (3C). All four lead to Stage 4.
i made these. they are free.
six tools my family uses to keep our kid under the fda action threshold. type your email. you get all six on this page in two seconds.
- 1. Baby-Proof Lead Risk Calculatoran 8-question read of your house. returns a risk band you can defend to a pediatrician.
- 2. Blood Lead Calculator1,370 foods scored by purity labs with icp-ms. type what your kid ate this week, get µg/day vs the fda irl.
- 3. Baby Food Database18,000 lots, updated daily. search by brand, ingredient, lot.
- 4. Baby Bottle Review Sheetevery bottle on the market scored on lead and the substances that show up next to it.
- 5. Leaducational Pages2,165 dishes scanned with a niton xl5 plus, sorted by brand and pattern.
- 6. Lead Framework Book106 pages. learn, examine, abate, detox, live. the parent protocol that runs the whole house.
here you go. six things, one tab each.
i copied your email to the list. the first email lands in a couple minutes. open the pack below now.
- 1. Baby-Proof Lead Risk Calculatoran 8-question read of your house and a band you can defend to a pediatrician.open →
- 2. Blood Lead Calculator1,370 foods scored by purity labs with icp-ms.open →
- 3. Baby Food Database18,000 lots. search by brand, ingredient, lot.open →
- 4. Baby Bottle Review Sheetevery bottle on the market scored on lead.open →
- 5. Leaducational Pages2,165 dishes scanned with a niton xl5 plus.open →
- 6. Lead Framework Book106 pages. learn, examine, abate, detox, live.open →
bookmark this page. the database and the leaducational pages update almost every day. the bottle sheet and the dish list grow as the lab finishes new runs.
or, if you want, grab a kit.
the information is free. the kit is for parents who, after reading the framework, decide they want to walk around the nursery with a drop bottle tonight. one drop of fluoro-spec on the painted side of a plate. if it's lead, it glows green in seconds. no lab.
see the drip kit, $50 →