Zinc is released from food as free ions during its digestion. These freed ions may then combine with endogenously secreted ligands before their transport into the enterocytes in the duodenum and jejunum.. Selected transport proteins may facilitate the passage of zinc across the cell membrane into the hepatic circulation. With high intake, zinc may also be absorbed through a passive paracellular route. The portal system carries absorbed zinc directly into the hepatic circulation, and then it is released into systemic circulation for delivery to various tissues. Although, serum zinc represents only 0.1% of the whole body zinc, the circulating zinc turns over rapidly to meet tissue needs.
Zinc can enter the body through the lungs, skin, and gastrointestinal tract. Intestinal absorption of zinc is controlled by zinc carrier protein CRIP. Zinc also binds to metallothioneins, which help prevent absorption of excess zinc. Zinc is widely distributed and found in all tissues and tissues fluids, concentrating in the liver, gastrointestinal tract, kidney, skin, lung, brain, heart, and pancreas. In the bloodstream zinc is found bound to carbonic anhydrase in erythrocytes, as well as bound to albumin, _2-macroglobulin, and amino acids in the the plasma. Albumin and amino acid bound zinc can diffuse across tissue membranes. Zinc is excreted in the urine and faeces. (L49)
Anaemia results from the excessive absorption of zinc suppressing copper and iron absorption, most likely through competitive binding of intestinal mucosal cells. Unbalanced levels of copper and zinc binding to Cu,Zn-superoxide dismutase has been linked to amyotrophic lateral sclerosis (ALS). Stomach acid dissolves metallic zinc to give corrosive zinc chloride, which can cause damage to the stomach lining. Metal fume fever is thought to be an immune response to inhaled zinc. (L48, L49, A49)
CLASSIFICATION: D; not classifiable as to human carcinogenicity. BASIS FOR CLASSIFICATION: Based on inadequate evidence in humans and animals. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Inadequate. /Zinc and compounds/
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌物分类
对人类无致癌性（未列入国际癌症研究机构IARC清单）。
No indication of carcinogenicity to humans (not listed by IARC).
Chronic exposure to zinc causes anemia, atazia, lethargy, and decreases the level of good cholesterol in the body. It is also believed to cause pancreatic and reproductive damage. (L49)
◉ Summary of Use during Lactation:Zinc is a normal component in human milk. Typical daily doses of 15 mg or less of oral zinc from prenatal vitamins or other multimineral supplements do not alter milk zinc levels in lactating women. Mothers may therefore take zinc supplementation during lactation to achieve the recommended daily intake of 12 to 13 mg. Daily oral doses between 15 and 25 mg have negligible effects on milk zinc levels.
Sublingual zinc lozenges and nasal sprays used to prevent or treat adult viral upper respiratory tract infections have not been studied during lactation. Maternal use of these remedies several times daily for short time periods, as they are typically intended to be used, would not be expected to cause harm to the breastfed infant.
Zinc deficiency in exclusively breastfed infants, whether due to inadequate maternal zinc status or to infant premature birth or other causes, should be treated with direct zinc supplementation of the infant.
Pasteurization by the Holder method does not change the concentration of zinc in milk.
◉ Effects in Breastfed Infants:Zinc deficiency in exclusively breastfed infants can occur. Clinical features include facial and groin rash, diarrhea, hair loss, disinterest in feeding, and failure to thrive. One known cause is below-normal milk zinc levels due to maternal genetic mutations affecting mammary zinc transport proteins. Zinc deficiency may also occur in infants born very preterm who are not supplemented with special human milk fortifiers designed for premature babies. With both causes, direct administration of zinc drops to the infant quickly corrects the deficiency and alleviate the infant’s symptoms.
Acrodermatitis enteropathica is a congenital zinc deficiency disorder caused by genetic mutations affecting the infant’s intestinal zinc transporter proteins. Breastmilk is protective against this disorder, which typically develops after weaning from breastmilk feeding. Resuming breastmilk feeding, if possible, and direct infant supplementation with zinc drops are the recommended treatments.
◉ Effects on Lactation and Breastmilk:Relevant published information was not found as of the revision date.
Zinc is absorbed in the small intestine by a carrier-mediated mechanism. Under regular physiologic conditions, transport processes of uptake do not saturate. The exact amount of zinc absorbed is difficult to determine because zinc is secreted into the gut. Zinc administered in aqueous solutions to fasting subjects is absorbed quite efficiently (at a rate of 60-70%), however, absorption from solid diets is less efficient and varies greatly, dependent on zinc content and diet composition. Generally, 33% is considered to be the average zinc absorption in humans. More recent studies have determined different absorption rates for various populations based on their type of diet and phytate to zinc molar ratio. Zinc absorption is concentration-dependent and increases linearly with dietary zinc up to a maximum rate. Additionally zinc status may influence zinc absorption. Zinc-deprived humans absorb this element with increased efficiency, whereas humans on a high-zinc diet show a reduced efficiency of absorption.
The excretion of zinc through gastrointestinal tract accounts for approximately one-half of all zinc eliminated from the body. Considerable amounts of zinc are secreted through both biliary and intestinal secretions, however most is reabsorbed. This is an important process in the regulation of zinc balance. Other routes of zinc excretion include both urine and surface losses (sloughed skin, hair, sweat). Zinc has been shown to induce intestinal metallothionein, which combines zinc and copper in the intestine and prevents their serosal surface transfer. Intestinal cells are sloughed with approximately a 6-day turnover, and the metallothionein-bound copper and zinc are lost in the stool and are thus not absorbed. Measurements in humans of endogenous intestinal zinc have primarily been made as fecal excretion; this suggests that the amounts excreted are responsive to zinc intake, absorbed zinc and physiologic need. In one study, elimination kinetics in rats showed that a small amount of ZnO nanoparticles was excreted via the urine, however, most of the nanoparticles were excreted via the feces.
A pharmacokinetic study was done in rats to determine the distribution and other metabolic indexes of zinc in two particle sizes. It was found that zinc particles were mainly distributed to organs including the liver, lung, and kidney within 72 hours without any significant difference being found according to particle size or rat gender.
Zinc salts are not equal in solubility, which is important in zinc absorption. The solubility of zinc salts is affected by gastric pH. Healthy subjects were given a single oral dose of 50 mg elemental zinc as the acetate ... under either high (pH > 5) or low (pH < 3) intragastric pH conditions. The mean plasma zinc area under the curve for zinc acetate at low pH (AL) /and/ ... at high pH (AH) ... were 524 /and/ 378 ... ug/hr/dL ...
Oxazolidine and thiazolidine derived carbodithioate compositions useful
申请人：Pennwalt Corporation
公开号：US03943143A1
公开（公告）日：1976-03-09
Oxazolidine and thiazolidinecarbodithioates, and pyridine adducts thereof, are accelerators for the vulcanization of EPDM elastomers, wherein they exhibit non-blooming characteristics.
Novel mercapto-substitued imidazolylporphyrin metal complex monomer, polymer having the same as a repeating unit and method of preparing the same
申请人：——
公开号：US20010027252A1
公开（公告）日：2001-10-04
A mercapto-substituted imidazolylporphyrin metal complex monomer represented by a general formula (1):
1
wherein R
1
represents a group selected from the group consisting of an alkyl group, unsubstituted aryl group, alkyl-substituted aryl group and alkyloxy-substituted aryl group, M represents a metal ion selected from the group consisting of Zn(II), Ga(III), Fe(II), Co(II), and Ru(II), X represents a divalent linking group containing at least one group selected from the group consisting of an arylene group and an alkylene group, R
2
represents a hydrogen atom or an acetyl group, and Im represents Im
1
or Im
2
set forth below:
2
wherein R
3
represents a hydrogen atom or an alkyl group.
Solution for removing thermal grease from electronic cards
申请人：——
公开号：US20010025016A1
公开（公告）日：2001-09-27
A water-free solution and method for dissolving and removing thermal grease from a high frequency logic device (e.g. a microprocessor in the form of a BGA and ASIC in the form of Quad Flat Pack component) assembled onto an electronic card which needs to be reworked. The method and solution of the present invention allow the complete removal of the grease by a simple and fast process, using an alcoholic, inert and cheap solution, without needing a mechanical action (e.g. brushing) and without damaging the card components. Furthermore, given the low surface tension of the alcoholic solution a good diffusion within the small holes and spaces of the card is ensured.
Pyridine adducts of oxazolidine and thiazolidine-derived carbodithioates
申请人：Pennwalt Corporation
公开号：US03976648A1
公开（公告）日：1976-08-24
Oxazolidine and thiazolidinecarbodithioates, and pyridine adducts thereof, are accelerators for the vulcanization of EPDM elastomers, wherein they exhibit non-blooming characteristics.
Inflammatory bowel disease preventive and curative agent containing zinc
申请人：Zeria Pharmaceutical Co., Ltd.
公开号：US05238931A1
公开（公告）日：1993-08-24
An agent for the prevention and treatment of inflammatory bowel disease (IBD) containing at least one of zinc L-carnosine salts and complexes as an active ingredient. A use of the zinc L-carnosine salts or complexes and a therapeutic method of IBD by using the same are also disclosed.
