Disability and even deaths from excessive use of these products have been claimed.The U.S. Food and Drug Administration (FDA) states that zinc damages nerve receptors in the nose, causing anosmia. Reports of anosmia were also observed in the 1930s when zinc preparations were used in a failed attempt to prevent polio infections. On June 16, 2009, the FDA ordered removal of zinc-based intranasal cold products from store shelves. The FDA said the loss of smell can be life-threatening because people with impaired smell cannot detect leaking gas or smoke, and cannot tell if food has spoiled before they eat it.Recent research suggests that the topical antimicrobial zinc pyrithione is a potent heat shock response inducer that may impair genomic integrity with induction of PARP-dependent energy crisis in cultured human keratinocytes and melanocytes. Poisoning
In 1982, the US Mint began minting pennies coated in copper but containing primarily zinc. Zinc pennies pose a risk of zinc toxicosis, which can be fatal. One reported case of chronic ingestion of 425 pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal sepsis. Another patient who ingested 12 grams of zinc showed only lethargy and ataxia (gross lack of coordination of muscle movements). Several other cases have been reported of humans suffering zinc intoxication by the ingestion of zinc coins.Pennies and other small coins are sometimes ingested by dogs, requiring veterinary removal of the foreign objects.
The main physiological requirement for ω-6 fatty acids is attributed to arachidonic acid. Arachidonic acid is the major precursor of prostaglandins, leukotrienes that play a vital role in cell signaling, and an endogenous cannabinoid anandamide. Metabolites from the ω-3 pathway, mainly from eicosapentaenoic acid, are mostly inactive, and this explains why ω-3 fatty acids do not correct the reproductive failure in rats where arachidonic is needed to make active prostaglandins that cause uterine contraction. To some extent, any ω-3 or ω-6 can contribute to the growth-promoting effects of EFA deficiency, but only ω-6 fatty acids can restore reproductive performance and correct the dermatitis in rats. Particular fatty acids are still needed at critical life stages (e.g. lactation) and in some disease states. In nonscientific writing, common usage is that the term essential fatty acid comprises all the ω-3 or -6 fatty acids. Conjugated fatty acids like calendic acid are not considered essential. Authoritative sources include the whole families, but generally only make dietary recommendations for LA and ALA with the exception of DHA for infants under the age of 6 months. Recent reviews by WHO/FAO in 2009 and the European Food Safety Authority have reviewed the evidence and made recommendations for minimal intakes of LA and ALA and have also recommended intakes of longer chain ω-3 fatty acids based on the association of oily fish consumption with a lower risk of cardiovascular disease.