The emissions are tiny, but Greenpeace argues that if all were ingested by humans, 30 million people would receive their entire "tolerable intake", according to international guidelines.

A couple of years ago, the Institute of Medicine issued a report listing "tolerable upper intake level" for all vitamins and minerals - the maximum safe amount that anyone should take.

They determined a tolerable daily intake(TDI) for FB1, FB2, FB3, alone or in combination of 2 g/kg body weight.

In 1970 the world Health Organisation established a 'tolerable weekly intake' of mercury and, although reviewed a number of times, this remains the same.

The recommendation for the highest tolerable intake of daily calcium is 2,500 milligrams of calcium a day.

The color additive can also increase the intake of aluminium beyond the tolerable weekly intake (TWI) of 1 mg/kg/week.

Recent human biomonitoring data shows that the tolerable intake of children is exceeded to a considerable degree, in some instances up to 20-fold.

The Food and Drug Administration did an extensive risk assessment of phthalates in the medical setting and found that neonates may be exposed to five times greater than the allowed daily tolerable intake.

The concept of tolerable daily intake is often used for unwanted contaminants or other chemicals.

This is why the WHO consultation group assessed the tolerable intake so as to prevent a woman from accumulating harmful body burdens before her first pregnancy.