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Zinc Chloride - Hazards Identification

EMERGENCY OVERVIEW: White odorless, granular crystals or crystalline powder; deliquescent (absorbs moisture from the air and forms wet solid or solution). Will not burn or support combustion. During a fire, corrosive and toxic hydrogen chloride gas and zinc oxide fume may be generated by thermal decomposition or combustion. CORROSIVE to the eyes and skin. May cause blindness, severe burns and permanent scarring.
POTENTIAL HEALTH EFFECTS:
Effects of Short-Term (Acute) Exposure
INHALATION:
Zinc chloride powder is unlikely to become airborne because it rapidly absorbs moisture forming a wet solid. Mists formed from solutions are probably severely irritating to the nose and throat, because zinc chloride is corrosive.
Prolonged or severe exposure may lead to a potentially fatal accumulation of fluid in the lungs (pulmonary edema). Symptoms of pulmonary edema (chest pain and shortness of breath) can be delayed up to 24 or 48 hours after exposure.
There is no specific human information available for zinc chloride, but severe lung damage has been observed in animals exposed to very high concentrations of zinc chloride aerosols. The term zinc chloride fume or zinc chloride smoke is often used to refer to the mixture of airborne chemicals produced by a type of smoke bomb used in firefighting exercises and as a screening smoke in the military. Igniting a mixture of zinc oxide and hexachloroethane produces this airborne smoke. While this smoke is generally referred to as "zinc chloride", it is a mixture of many different chemicals including zinc chloride, zinc oxychloride, phosgene, tetrachloroethylene, carbon tetrachloride, carbon dioxide, carbon monoxide and hexachloroethane.(30) The hazards of this smoke are not addressed in this CHEMINFO review. However, the effects include symptoms from slight respiratory distress to pulmonary edema, acute respiratory distress and death. (13,30,32)
SKIN CONTACT:
Contact with the powders or solutions can cause severe irritation or corrosive effects, based on animal information and the pH of solutions. Corrosive materials can cause severe skin injury with ulceration, blistering and permanent scarring. Zinc can be absorbed into the body following application of zinc chloride to the skin, based on animal information. However, there is no evidence that harmful effects can result by this route of exposure.
EYE CONTACT:
Zinc chloride powder or solutions can cause corrosive injury, based on human evidence, limited animal information and the pH of solutions. The degree of injury depends on the concentration of the solution and the duration and extent of contact with the eye. In severe cases, permanent eye injury, including blindness, could result. Very dilute solutions (up to 1%) are non-irritating and have been used as eye drops. Very severe eye injury has been reported in cases where concentrated solutions and pastes were accidentally splashed into the eye. In some cases, the effects were not fully reversible.(2, unconfirmed)
INGESTION:
Zinc chloride is corrosive and ingestion can result in severe injury to the mouth, throat and stomach. Death has reportedly resulted after ingestion of a few grams of zinc chloride, although in another case recovery occurred after ingestion of 90 grams.(27, unconfirmed) Like other zinc compounds, ingestion of large amounts can cause anemia and stomach symptoms (including nausea, vomiting, abdominal pain, diarrhea and, in severe cases, vomiting of blood), based on human and animal information.(18,24,25,32) In one case of accidental ingestion, burning and pain in the throat and mouth, abdominal pain and vomiting, and enzyme levels suggestive of acute pancreatitis resulted from accidental ingestion of 3 ounces of a zinc chloride solution (concentration not specified) by a 24-year old man.(57) Other case studies of ingestion of zinc compounds have also found increases in pancreatic enzymes.(29,32)
Zinc is an essential nutrient to humans and animals. Both zinc deficiency and overexposure to zinc by ingestion have been associated with toxic effects.(18) Ingestion is not a typical route of occupational exposure.
Effects of Long-Term (Chronic) Exposure
Zinc chloride is corrosive and long-term exposure is expected to be limited due to the severe irritant effects of this chemical.
Zinc is a very important trace element for humans. It is an important constituent of many enzymes and other proteins and has an essential role in many processes of normal growth and development. For zinc compounds in general, a number of reversible harmful effects (red and white blood cell deficiencies (anemia and leukopenia), headache and stomach symptoms, and copper deficiency) have resulted from long-term ingestion (doses as low as 2 mg zinc/kg/day), based on non-occupational human reports and animal information.(18,24,29)
RESPIRATORY SENSITIZATION:
There is insufficient information available to conclude that zinc chloride is an occupational sensitizer.
A case report of occupational asthma in a 19-year-old, non-smoking woman who was exposed daily to fumes from solder flux composed of zinc chloride and ammonium chloride was located. All symptoms disappeared when she was removed from exposure. She had no personal history of asthma, but her father and brother had histories of allergies.(28) Two other cases attributable to soft solder flux containing zinc and ammonium chlorides have been described.(60) In all of these cases, exposure was not to zinc chloride alone, but was a combined exposure to the all of the components of the solder flux.
SKIN:
Repeated or prolonged contact may cause dry, red, and cracked skin (dermatitis), due to the corrosiveness of zinc chloride.
SKIN SENSITIZATION:
Zinc chloride is not an occupational skin sensitizer. One non-occupational case report describes sensitization to zinc chloride in a woman who developed dermatitis, headache, excessive sweating and lethargy after receiving a zinc-containing dental filling. Patch testing indicated that zinc chloride was the allergen. However, it is considered a very rare allergen.(23) No occupational case reports were located.
BLOOD/BLOOD FORMING SYSTEM:
Conclusions cannot be drawn from a single historical case report of a 34-year-old man whose hands and forearms were exposed to zinc chloride powder and the 34% water solution, which he made up 3 times a week for 4 years. He was also likely exposed to the zinc chloride by inhalation of a steam that was formed. He experienced leg pains, anemia, fatigue, loss of appetite and loss of weight, which improved when he was removed from the zinc exposure.(22)
CARCINOGENICITY:
Zinc and its compounds are not known to be carcinogenic. There is no human information available for zinc chloride. Zinc chloride did not cause a promoting effect following administration with known carcinogens, based on animal information. No conclusions can be drawn from an unconfirmed, limited study using mice.
The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.
The American Conference of Governmental Industrial Hygienists (ACGIH) has not assigned a carcinogenicity designation to this chemical.
The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.
TERATOGENICITY AND EMBRYOTOXICITY:
There is no human information or relevant animal information available for zinc chloride. In general, zinc compounds are not known to cause developmental toxicity in the absence of maternal toxicity.
REPRODUCTIVE TOXICITY:
There is no human information available for zinc chloride. It is not possible to conclude that zinc chloride is a reproductive toxin, based on the available animal information. The studies are mostly limited by small animal numbers or provide inadequate details for evaluation. In one study, which was limited by small animal numbers, ingestion of zinc chloride caused reduced fertility at doses that caused other significant harmful effects.
MUTAGENICITY:
There is no human information available for zinc chloride. It is not possible to conclude that zinc chloride is mutagenic, based on the available animal information. A negative result was obtained in a test using live mice exposed orally. Other studies with live animals used routes of exposure that are not relevant to occupational situations. Both positive and negative results were obtained in tests with cultured mammalian cells and bacteria. A positive result was obtained in fruit flies (Drosophila).
TOXICOLOGICALLY SYNERGISTIC MATERIALS:
When zinc is absorbed into the body, it interacts with other trace elements, especially copper. It also competes with other metals, such as lead or mercury, which may sometimes reduce the harmful effects of these metals.
POTENTIAL FOR ACCUMULATION:
Zinc can accumulate in the body. Intestinal absorption of zinc can vary widely following oral administration (in animals ranges of less than 10 to over 90% are reported) and is influenced by age and a number of dietary factors. Zinc is stored mainly in the muscle and bone, and also in the prostate, liver, gastrointestinal tract, kidneys, skin, lung, brain, heart and pancreas.(58,59) In humans ingesting normal amounts of zinc, the reported half-lives ranged from 100-500 days.(58) The body regulates the amount of zinc stored by decreasing absorption and increasing excretion when intake is increased.(29) It is excreted mainly in the feces.(58)