Sulfur (Sulphur)
The amino acids cysteine and methionine contain sulfur, as do all polypeptides,
proteins, and enzymes which contain these amino acids. This makes sulphur a
necessary component of all living cells.
Although sulfur dioxide is sufficiently safe to be used as a food additive in
small amounts, at high concentrations it reacts with moisture to form sulfurous
acid which in sufficient quantities may harm the lungs, eyes or other tissues.
In creatures without lungs such as insects or plants, it otherwise prevents
respiration.
Hydrogen sulfide is highly toxic (more toxic than cyanide). Although very pungent
at first, it quickly deadens the sense of smell, so potential victims may be
unaware of its presence until it is too late.
