Boric acid, also called hydrogen borate, boracic acid, orthoboric acid and acidum boricum, is a weak, monobasic Lewis acid of boron often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other chemical compounds. It has the chemical formula H3BO3 (sometimes written B(OH)3), and exists in the form of colorless crystals or a white powder that dissolves in water. When occurring as a mineral, it is called sassolite.
Boric acid, or sassolite, is found natively in its free state in some volcanic districts, for example, in the Italian region of Tuscany, the Lipari Islands and the US state of Nevada. In these volcanic settings it issues, mixed with steam, from fissures in the ground. It is also found as a constituent of many naturally occurring minerals – borax, boracite, ulexite (boronatrocalcite) and colemanite. Boric acid and its salts are found in seawater. It is also found in plants, including almost all fruits.[1]
Boric acid was first prepared by Wilhelm Homberg (1652–1715) from borax, by the action of mineral acids, and was given the name sal sedativum Hombergi ("sedative salt of Homberg"). However borates, including boric acid, have been used since the time of the Greeks for cleaning, preserving food, and other activities.[citation needed]
Based on mammalian median lethal dose (LD50) rating of 2,660 mg/kg body mass, boric acid is poisonous if taken internally or inhaled in large quantities. The Thirteenth Edition of the Merck Index indicates that the LD50 of boric acid is 5.14 g/kg for oral dosages given to rats, and that 5 to 20 g/kg has produced death in adult humans. For comparison's sake, the LD50 of salt is reported to be 3.75 g/kg in rats according to the Merck Index. But this is highly misleading, as humans have been known to die from amounts only a small fraction of the LD50. "The minimal lethal dose of ingested boron (as boric acid) was reported to be 2–3 g in infants, 5–6 g in children, and 15–20 g in adults", according to the Agency for Toxic Substances and Disease Registry.[11]
Long term exposure to boric acid may be of more concern, causing kidney damage and eventually kidney failure (see links below). Although it does not appear to be carcinogenic, studies in dogs have reported testicular atrophy after exposure to 32 mg/kg bw/day for 90 days. This level is far lower than the LD50.[12]
According to boric acid IUCLID Dataset published by the European Commission, boric acid in high doses shows significant developmental toxicity and teratogenicity in rabbit, rat, and mouse fetuses as well as cardiovascular defects, skeletal variations, mild kidney lesions.[13] As a consequence, in August 2008, in the 30th ATP to EU directive 67/548/EEC, the EC decided to amend its classification as reprotoxic category 2 and to apply the risk phrases R60 (may impair fertility) and R61 (may cause harm to the unborn child).[14][15][16][17][18]
At a recent European Diagnostics Manufacturing Association (EDMA) Meeting, several new additions to the Substance of Very High Concern (SVHC) candidate list in relation to the Registration, Evaluation, Authorisation and restriction of Chemicals Regulations 2007 (REACH) were discussed. The registration and review completed as part of REACH has meant the current classification of Boric Acid CAS 10043-35-3 / 11113-50-1 as of 1 December 2010 will be listed as H360FD (May damage fertility. May damage the unborn child.)[19][20]
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กรด boric เรียกว่าไฮโดรเจน borate กรด boracic, orthoboric กรดและ acidum boricum กรดลูอิสอ่อนแอ monobasic ของโบรอนที่มักใช้เป็นยาฆ่าเชื้อ กำจัด แมลง หน่วง วิบากนิวตรอน การสารตั้งต้นกับสารเคมีอื่น ๆ ได้ มี H3BO3 สูตรเคมี (บางครั้งเขียน B(OH)3) และอยู่ในรูปของผลึกไม่มีสีหรือผงสีขาวที่ละลายในน้ำ เมื่อเกิดเป็นแร่ มันคือ sassoliteกรด boric, sassolite จะพบวิธีในสถานะอิสระในเขตภูเขาไฟบาง เช่น ในแคว้นทัสคานี เกาะ Lipari และรัฐเนวาดาสหรัฐอเมริกาอิตาลี ในภูเขาไฟตั้งค่าเหล่านี้มันออก ผสมกับไอน้ำ จาก fissures ในพื้นดิน นอกจากนี้ยังพบเป็นวิภาคหลายเกิดขึ้นตามธรรมชาติแร่ – borax, boracite, ulexite (boronatrocalcite) และ colemanite กรด boric และเกลือที่พบในน้ำทะเล นอกจากนี้ยังพบในพืช การรวมผลไม้เกือบทั้งหมด [1]กรด boric ได้ก่อนเตรียม โดยวิลเฮล์ม Homberg (1652 – 1715) จาก borax โดยการกระทำของกรดแร่ และให้แซลชื่อ sedativum Hombergi ("sedative เกลือของ Homberg") อย่างไรก็ตาม borates กรด boric รวมทั้งมีการใช้ตั้งแต่เวลากรีกสำหรับทำความสะอาด รักษาอาหาร และกิจกรรมอื่น ๆ [ต้องการอ้างอิง]Based on mammalian median lethal dose (LD50) rating of 2,660 mg/kg body mass, boric acid is poisonous if taken internally or inhaled in large quantities. The Thirteenth Edition of the Merck Index indicates that the LD50 of boric acid is 5.14 g/kg for oral dosages given to rats, and that 5 to 20 g/kg has produced death in adult humans. For comparison's sake, the LD50 of salt is reported to be 3.75 g/kg in rats according to the Merck Index. But this is highly misleading, as humans have been known to die from amounts only a small fraction of the LD50. "The minimal lethal dose of ingested boron (as boric acid) was reported to be 2–3 g in infants, 5–6 g in children, and 15–20 g in adults", according to the Agency for Toxic Substances and Disease Registry.[11]Long term exposure to boric acid may be of more concern, causing kidney damage and eventually kidney failure (see links below). Although it does not appear to be carcinogenic, studies in dogs have reported testicular atrophy after exposure to 32 mg/kg bw/day for 90 days. This level is far lower than the LD50.[12]According to boric acid IUCLID Dataset published by the European Commission, boric acid in high doses shows significant developmental toxicity and teratogenicity in rabbit, rat, and mouse fetuses as well as cardiovascular defects, skeletal variations, mild kidney lesions.[13] As a consequence, in August 2008, in the 30th ATP to EU directive 67/548/EEC, the EC decided to amend its classification as reprotoxic category 2 and to apply the risk phrases R60 (may impair fertility) and R61 (may cause harm to the unborn child).[14][15][16][17][18]
At a recent European Diagnostics Manufacturing Association (EDMA) Meeting, several new additions to the Substance of Very High Concern (SVHC) candidate list in relation to the Registration, Evaluation, Authorisation and restriction of Chemicals Regulations 2007 (REACH) were discussed. The registration and review completed as part of REACH has meant the current classification of Boric Acid CAS 10043-35-3 / 11113-50-1 as of 1 December 2010 will be listed as H360FD (May damage fertility. May damage the unborn child.)[19][20]
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