The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals. 137. Ammonia
"Ammonia (NH3) is a colourless gas with a distinctly pungent odour at normal atmospheric temperatures and pressures. The odour threshold is approximately 5 ppm. Ammonia can be liquefied under pressure. In aqueous solution, NH3 acts as a base yielding ammonium (NH4+) and hydroxide (OH-) ions. Be...
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| Institution: | ETUI-European Trade Union Institute |
| Format: | TEXT |
| Language: | English |
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Stockholm
2005
NIWL |
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| Online Access: | https://www.labourline.org/KENTIKA-19138320124919565029-The-Nordic-expert-Group-for-Cr.htm |
| Summary: | "Ammonia (NH3) is a colourless gas with a distinctly pungent odour at normal atmospheric temperatures and pressures. The odour threshold is approximately 5 ppm. Ammonia can be liquefied under pressure. In aqueous solution, NH3 acts as a base yielding ammonium (NH4+) and hydroxide (OH-) ions. Because of the high water solubility ammonia dissolves in moisture on the mucous membranes, eyes and skin, forming ammonium hydroxide, which may cause alkali burns and liquefaction necrosis of the tissues.Ammonia occurs naturally in the environment and is endogenously produced in humans and other mammalians. It is also man-made in vast quantities. Occupational exposures may occur in ammonia plants, fertiliser manufacturing, and animal production. The primary route of occupational exposure to ammonia is inhalation, although dermal exposure may also occur during handling of liquid ammonia or aqueous ammonia solutions.
The critical effect of exposure to ammonia is irritation. In controlled human exposure studies (3-4 hours) clear signs of mild respiratory and eye irritation appear somewhere between 25 and 50 ppm. In one of these studies very slight irritation was seen at 5 ppm. NEG considers 5 ppm as a pragmatic NOAEL and 25 ppm as a LOAEL for irritation. Chronic exposure to average ammonia levels above 25 ppm has been associated with an increase in respiratory symptoms (cough, wheezing, phlegm, and dyspnoea) and bronchial asthma. High acute exposure levels may result in reactive airways dysfunction syndrome (RADS), an asthma-like syndrome with persistent bronchial hyperreactivity but no sensitisation. Massive exposure to ammonia can cause eye damage, skin burns, severe inflammation of the respiratory tract (laryngitis, tracheobronchitis, and pulmonary oedema), and death. With very limited data available, there is no evidence that ammonia possesses genotoxic, carcinogenic or reprotoxic potential." |
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| Physical Description: | 52 p. Digital |