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There are a number of sources that claim 18th century aristocrats contracted lead poisoning from eating tomatoes off of pewter plates:

Because tomatoes are so high in acidity, when placed on this particular tableware, the fruit would leach lead from the plate, resulting in many deaths from lead poisoning

This is presented as one reason for the slow adoption of tomatoes in European cuisine.

There are a couple of things I question about this claim:

  1. There are plenty of common foods that are more acidic than tomatoes, e.g. vinegar, red wine, apples. If this was happening with tomatoes, it should be happening quite frequently;
  2. My understanding is that lead poisoning takes time to develop, which would make the attribution "eating tomatoes makes me sick" difficult or impossible.

The CDC recommends adults stay below 10 µg/dl blood lead - how much would need to be eaten daily over a long period of time to reach those levels? Alternatively, how much lead would need to be eaten in a single sitting to cause symptoms of acute lead toxicity?

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Poisoning from acute exposure will depend on the form of the lead. Elemental lead is poorly absorbed, whereas lead salts are much more likely to cause toxicity, so 0.5g of elemental lead in the form of a salt can be fatal. (Source: UK National Poisons Information Service via Toxbase website).

UK legal limits in occupational exposure are slightly higher - action is needed if blood levels reach 50mcg/dl (25mcg/dl in 'women of child bearing age' and 40mcg/dl for young people). As Ian Campbell pointed out in the comments, US guidance is tighter with treatment advised in children levels over 35mcg/dL.

Chronic exposure is trickier to work out. Absorption for lead salts is reported to be higher in children (50-80%) than adults (3-10%). In the steady state, most lead is stored in bone whereas the toxic level is based on the blood concentration. Ingestion, movement between compartments, and excretion occur at different rates; models have existed for a long time but also show significant variability between individuals.

Also worth noting that absorption of lead is highly variable - depending on particle size, inhaled lead may be better absorbed than ingested, and deficiency of calcium or zinc, and some genetic variations, also lead to higher uptake.

An ingested dose of 100mcg/day for a year was modelled to give an increase in steady state lead levels of 3.3-8.4 mcg/dl. While this is not entirely 'safe' it would still be below the limit you discussed in the question, and would suggest that a daily ingested dose of around 120-300mcg would reach that blood concentration.

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    I think "action is needed if blood levels reach ... 40mcg/dL for young people" might be a bit misleading. At least in my municipality here in the US, we start intervening in a child's environment if venous blood is greater than 3.5mcg/dL and start chelation therapy at 45mcg/dL.
    – Ian Campbell
    Dec 22, 2023 at 17:01
  • @IanCampbell I've rechecked the references. Accept they are UK based, but chelation started in children if encephalopathic or blood level above 70mcg/dL (3.3 micromol/L). 40mcg/dL relates to occupational exposure - in a domestic setting would be less reason for any significant exposure and would aim to control more tightly.
    – Michael
    Dec 22, 2023 at 17:44
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    The American Academy of Pediatrics is where the 45mcg/dL threshold comes from.
    – Ian Campbell
    Dec 22, 2023 at 19:30
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    Difficult to impossible to cover rules in every country but I have included you link alongside the UK one to show that variation exists.
    – Michael
    Dec 22, 2023 at 20:37

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