Cookware Cookware in which<unk>  is the main structural element (as opposed to<unk>  clad,<unk>  sandwiched or<unk>  colored) is sometimes manufactured without a lining when intended to be used for any of a number of specific culinary tasks, such as preparing preserves or meringues. Otherwise,<unk>  cookware is lined with a non-reactive metal to prevent contact between acidic foods and the structural<unk>  element of the cookware. Excepting for acute or chronic conditions, exposure to<unk>  in cooking is generally considered harmless. According to Paracelsus, dosage makes the poison; as this pertains to<unk>  "a defense mechanism has apparently evolved as a consequence of which toxicity in man is very unusual." Acute exposure and attendant<unk>  is possible when cooking or storing highly acidic foods in unlined<unk>  vessels for extended periods, or by exposing foodstuffs to reactive<unk>  salts<unk>  corrosion, or verdigris). Continuous, small ("chronic") exposures of acidic foods to<unk>  may also result in toxicity in cases where either surface area interaction potentials are significant, pH is exceptionally low and concentrated (in the case of cooking with, for example, vinegar or wine), or both, and insufficient time elapses between exposures for normal homeostatic elimination of excess<unk> . Exceptions to the above may be observed in the case of jam, jelly and preserve -making, wherein unlined<unk>  vessels are used to cook (not to store) acidic preparations, in this case of fruit. Methods of jamming and preserving specify sugar as chemically necessary to the preserving (antibacterial) action, which has the additional effect of mediating (buffering) the interaction of fruit acid with<unk> , permitting the use of the metal for its efficient thermal transfer properties. Non-sparking tools OSHA has set safety standards for grinding and sharpening<unk>  and<unk>  alloy tools, which are often used in nonsparking applications. These standards are recorded in the Code of Federal Regulations 29 CFR 1910.134 and 1910.1000. Note: The most important nonsparking<unk>  alloy is beryllium<unk> , and can lead to beryllium poisoning. Drinking water With an of 30 mg/kg in rats, "gram quantities" of<unk>  sulfate are potentially lethal in humans. The suggested safe level of<unk>  in drinking water for humans varies depending on the source, but tends to be pegged at 1.3 mg/l. Birth control There are conditions in which an individual's<unk>  metabolism is compromised to such an extent that birth control may cause an issue with<unk>  accumulation. They include toxicity or just increased<unk>  from other sources, as well as the increased<unk>  level of the individual's mother via the placenta before birth.
Copper toxicity
Zinc toxicity
Fluoride toxicity
Lead poisoning
Chromium toxicity
Boron deficiency 
Mercury poisoning
Metal toxicity