Don't overlook that although less is always better, levels of heavy metals should be seen in relation to the intake (of a dietary supplement or another food) and the bodyweight of the individual consuming it. For a baby 1ppm of whatever compound might be toxic, whereas for an adult man it is perfectly safe. The danger is in the dosage !!
Below are the official EU and World Health Organisation / Joint Expert Committee on Food Additives (WHO / JECFA) guidelines. The amounts are in mcg (micrograms).
- Arsenic: (Adult, 70 kgs: 150 mcg = daily limit)
- Cadmium: (Adult, 70 kgs: 70 mcg daily = daily limit)
- Lead: (Adult, 70 kgs: 250 mcg daily = daily limit)
- Mercury: (Adult, 70 kgs: 16 mcg daily = daily limit)
Of course it is also interesting to know how much heavy metals are present in common everyday foods.
To compare, in 2007 the FDA conducted a survey to determine levels of heavy metals such as lead in typical foods. The majority of foods were free or almost free of any heavy metals, but not all. There was no difference between 'organic' and standard.
Their most striking results (levels per serving, per day):
- fresh collard greens: 30 microgram of lead
- dry roasted mixed nuts: 20 microgram of lead
- Brussels sprouts 15 microgram of lead
- Sweet potatoes : 16 microgram of lead
- Spinach: 15 microgram of lead
These are all considered normal and safe levels.