Release of nickel and chromium in common foods during cooking in 18/10 (grade 316) stainless steel pots.

Background. Literature data on the release of nickel and chromium from stainless
steel cookware during food preparation are contrasting, have often been obtained with
uncommon foods and/or procedures, and are thus not widely applicable.
Objectives. To assess the release of nickel and chromium from 18/10 (grade 316)
stainless steel pots in cooking conditions that are common in an urban lifestyle.
Methods. Tomato sauce and lemon marmaladewere cooked for 1 h, alone orwith added
EDTA, in used or unused stainless steel pots from different manufacturers. Additionally,
aqueous solutions at pH 2.3, 7.7 and 9 were boiled for 1 h in the same pots. Metal release
was assessed with inductively coupled plasma mass spectrometry.
Results. The release of nickel and chromium increased with cooking/boiling time, was
higher with unused pots, at low pH or with EDTA, and was sometimes remarkably
different between manufacturers. In all experiments, the amounts released were below
known allergy-triggering thresholds.
Conclusions. Under common conditions, the use of 18/10 stainless steel pots is considered
to be safe for the majority of nickel-allergic and/or chromium-allergic subjects. However,
the total amount of nickel contained in foods and released from potsmay exceed the
individual threshold for triggering allergy, potentially causing problems for highly sensitive
patients, or, conversely, contribute to induction of immunotolerance by oral low-dose
exposure.