>>319667
From Grok:
One standard can of tuna contains roughly 10–13 µg (micrograms) of mercury if it’s light tuna (the most common type), or about 30–35 µg if it’s albacore/white tuna. This is based on official FDA testing data. The imageboard guy’s diet (1 can tuna + 3 cans sardines daily) would deliver a total of roughly 16 µg mercury per day with light tuna—or ~39 µg/day with albacore—which exceeds the EPA’s recommended reference dose for most adults and is not advisable long-term.
Exact FDA Mercury Levels
Here are the authoritative numbers from the FDA’s monitoring program (1990–2012 data, hundreds of samples per category):
Canned light tuna (skipjack, the usual “chunk light” or “light tuna” in cans): Mean 0.126 ppm (µg/g). Median 0.077 ppm. Range: not detected up to 0.889 ppm (545 samples).
Canned albacore (white) tuna: Mean 0.350 ppm. Median 0.338 ppm. Range up to 0.853 ppm (451 samples).
Sardines (for reference, from your previous question): Mean 0.013 ppm. Median 0.010 ppm. Range up to 0.083 ppm (90 samples).
These are among the most reliable large-scale U.S. government figures. Light tuna averages about 10 times more mercury than sardines; albacore averages about 27 times more.
Typical Can Sizes and Mercury per Can
Canned fish weights refer to the drained solids (edible fish after pouring off liquid/oil):
Standard sardine can (e.g., 3.75 oz / ~106 g net weight): ~92 g drained fish → ~1.2 µg mercury per can (using the 0.013 ppm mean).
Standard tuna can (5 oz / 142 g net weight, the most common size): ~85–99 g drained fish (typically ~3–3.5 oz / 85–99 g). Using ~100 g for a realistic average:
Light tuna: ~12.6 µg mercury per can.
Albacore/white tuna: ~35 µg mercury per can.
For the described diet (1 tuna can + 3 sardine cans daily, assuming ~95–100 g fish per can):
Light tuna version: ~12.6 µg (tuna) + 3.6 µg (3× sardines) = ~16.2 µg total mercury/day.
Albacore version: ~35 µg (tuna) + 3.6 µg = ~38.6 µg total mercury/day.
Is This Safe? Comparison to Guidelines
The EPA’s reference dose (RfD) for methylmercury—the toxic form in fish—is 0.1 µg per kg of body weight per day. This is a conservative daily limit with built-in safety margins:
60 kg (132 lb) person: 6 µg/day max.
70 kg (154 lb) person: 7 µg/day max.
80 kg (176 lb) person: 8 µg/day max.
Your guy’s diet exceeds this by 2–2.7× (light tuna) or 5–6× (albacore) every single day.
The FDA/EPA joint fish advice chart classifies:
Canned light tuna as a “Best Choice” — safe at 2–3 servings per week (a serving = 4 oz / 113 g drained) for pregnant/breastfeeding people and children. General adults can have more but should vary their fish.
Canned albacore/white tuna as a “Good Choice” — limited to 1 serving per week.
Daily tuna (even light) goes well beyond these recommendations. Chronic intake at these levels raises the risk of subtle neurological or cardiovascular effects over months/years, though individual tolerance varies (body weight, genetics, overall diet, and selenium intake all matter). Sardines are excellent here—they’re very low in mercury and rich in selenium, which can help bind and reduce mercury’s effects.
Other Factors
Variability: Not every can is average. Some light tuna tests have hit near 0.9 ppm; albacore can be higher. Brands that test every fish (rare) or source carefully are better.
The diet overall: Nutritionally solid in protein, omega-3s, and (from sardines) calcium/vitamin D if bones are eaten. But the daily tuna is the weak point for mercury. Better versions: Rotate tuna with other “Best Choice” fish (salmon, sardines only, anchovies, etc.), or do tuna only 2–3×/week max.
Who should be extra cautious: Pregnant/breastfeeding people, young children, and anyone planning long-term high-fish diets. The rest of the population has more buffer, but “only tuna + sardines forever” isn’t ideal.
Bottom line: One can of light tuna has about 12–13 µg mercury on average; albacore has ~35 µg. The full daily diet the guy described delivers 16+ µg (light) or 39 µg (albacore)—well above prudent daily limits. It’s probably fine short-term for a healthy adult but not a sustainable long-term plan without rotation or monitoring. If he’s doing this, suggest he switch to all sardines (or add other low-mercury options) most days and save tuna for occasional variety. For personalized advice, a doctor or a mercury exposure calculator based on exact body weight/fish brands can help.