Thiocyanate

Warning

H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]

P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

The GHS information provided by 1 company from 1 notification to the ECHA C&L Inventory.

In cases of thiocyanate exposure, get fresh air and medical attention. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. If swallowed, do not induce vomiting but give large quantities of water. Immediately flush skin with plenty of water for at least 15 minutes in case of exposure to skin or the eyes. (L217)

Thiocyanates are known to affect the thyroid glands, reducing the ability of the gland to produce hormones that are necessary for the normal function of the body. Exposure to high levels of cyanide for a short time harms the brain and heart and can even cause coma and death. (L191)

Thiocyanate (sulphocyanate or SCN) is believed to be a goitrogenic compound. It is a competitive inhibitor of the human thyroid sodium/iodide symporter NIS. Thus, the adverse effects of thiocyanate overload are especially noticeable when iodine availability is low. Intake of goitrogenic substances causes an adaptive increase in T3‰ЫЄs binding to brain nuclear receptors and in the activity of type II 5'-deiodinase, which generates T3 from T4. This altered function and availability of T3 is detrimental to the developing brain. Thiocyanate is also known to modulate activity of mammalian peroxidases. For instance, eosinophil peroxidase has been implicated in promoting oxidative tissue damage in a variety of inflammatory conditions, including asthma. Thiocyanate also acts as inhibitor to carbonic anhydrase, which catalyzes the rapid conversion of carbon dioxide to bicarbonate and protons. (A139, A143, A149) Organic nitriles decompose into cyanide ions both in vivo and in vitro. Consequently the primary mechanism of toxicity for organic nitriles is their production of toxic cyanide ions or hydrogen cyanide. Cyanide is an inhibitor of cytochrome c oxidase in the fourth complex of the electron transport chain (found in the membrane of the mitochondria of eukaryotic cells). It complexes with the ferric iron atom in this enzyme. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted and the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Cyanide is also known produce some of its toxic effects by binding to catalase, glutathione peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, succinic dehydrogenase, and Cu/Zn superoxide dismutase. Cyanide binds to the ferric ion of methemoglobin to form inactive cyanmethemoglobin. (L97)

Thiocyanates can appear in the body after metabolization of cyanides by rhodanese. When thiocyanates enter the body, they normally breaks down in aqueous solution to yield sulfate ions. However, thiocyanates are also found in the thyroid fluids. Immediately following exposure to thiocyanate containing solutions, the cystic fibrosis conductance regulator Cl‰ЫТ channel exhibits high unitary SCN‰ЫТ conductance and anomalous mole fraction behaviour. Thiocyanates is normally excreted in urine. (A140, A142, A143, A144) Organic nitriles are converted into cyanide ions through the action of cytochrome P450 enzymes in the liver. Cyanide is rapidly absorbed and distributed throughout the body. Cyanide is mainly metabolized into thiocyanate by either rhodanese or 3-mercaptopyruvate sulfur transferase. Cyanide metabolites are excreted in the urine. (L96)

Exposure occurs from breathing air and drinking water, touching soil or water containing thiocyanate, or eating foods that contain thiocyanate. Thiocyanates are present in water primarily because of discharges from coal processing, extraction of gold and silver, and mining industries. Thiocyanate is the major product formed from cyanide that passes into the body as the body attempts to rid itself of cyanide, thus exposure to cyanide also results in exposure to thiocyanate. (L191)