Hazards acute effects

Diseased subjects Few covariates Vulnerable persons Cause-effect Acute effects only Hazards Public acceptance... 

Further information gained from accidental human exposures could be utilized in defining the lowest air level that affects humans. Similarly, studies on the acute effects of dermal exposure to trichloroethylene in animals may be useful in determining the risk for these exposures in humans at hazardous waste sites. However, there appear to be sufficient data available on neurological effects after acute inhalation exposure. 

Considerable controversy continues to exist as to what concentration of HC1 is hazardous to man. Although numerous studies of the acute effects of HQ have been conducted with rodents, it is questionable whether lethality data from rodents can be directly extrapolated to man because of anatomical differences in the respiratory tract... 

As studies in human volunteers are performed under standardized conditions with well-defined exposure concentrations or doses, but only for a short duration, such studies are most relevant for hazard assessment of mild acute effects, mild irritation, sensitization, toxicokinetics, and mode of action(s). 

Where information is available on toxic signs of acute toxicity and the dose levels at which these signs occur, then this is useful information that can aid in the hazard and risk assessment for acute toxicity. Equally, dose levels leading to no acute effects can provide useful information. 

Acute effects often involve the central nervous system, because of the rapid absorption of the solvent from the lungs and direct distribution to the brain. The immediate effects may result in mild impairment of judgment or drowsiness. In most situations these effects are not serious and will end quickly once exposure stops. In some circumstances a slight lapse of judgment could be disastrous. A person responding to a hazardous material spill or perhaps a fire must take appropriate precautions to limit exposure to any solvents that could impair judgment and thus increase risk of injury. 

Lead is an acute and a chronic toxicant. Acute effects are ataxia, headache, vomiting, stupor, hallucination, tremors and convulsions. Chronic symptoms from occupational exposure include weight loss, anemia, kidney damage and memory loss. (Patnaik, P. 1999. A Comprehensive Guide to the Hazardous Properties of Chemical Substarwes, 2nbrain damage has been noted among children. Lead bioaccumulates in bones and teeth. The metal is classified as an environmental priority pollutant by the US EPA. 

Phosphine is a highly toxic and flammable gas. Acute effects are irritation, tightness of chest, painful breathing, and lung damage. High concentration can be fatal. A fire hazard. 

Potassium cyanide is a dangerously toxic substance. Ingestion of 100 to 150 mg can cause collapse and cessation of breathing in humans. At lower doses, the acute effects are nausea, vomiting, headache, confusion and muscle weakness (Patnaik, P. 1999. A Comprehensive Guide to the Hazardous Properties of Chemical Substances, ed. pp. 292-294. New York John Wdey Sons). Contact with acid can liberate highly toxic vapors of hydrogen cyanide. Sodium thiosulfate and sodium sulfate have shown antidotal activity to KCN toxicity. 

It is quite clear that traditional risk assessment and risk management approaches are not working sufficiently well in the field of chemicals policy, in particular not in cases of high uncertainty. The traditional approach could hardly deal with the early chemical problems, characterised by evident impacts such as acute effects, and is even less effective in the present situation, with globalised flows of articles that contain hazardous chemicals and the resulting complex chemical cocktail, which may cause diffuse but significant adverse effects on human health and the environment. 

The reason for setting a TLV varies depending on the nature of the effect it may cause. For this reason, they cannot be used to compare the relative hazards of materials. For instance, one substance may cause an acute effect such as eye and respiratory irritation while another may cause chronic carcinogenic effects. Clearly, these effects are very different, and thus the substances TLVs are likely to be dissimilar as well. 

Benzene can have both chronic and acute toxic effects. The risk of acute effects is low, since acute symptoms occur only at 1000 ppm or higher. Chronic vapor inhalation at the level of 25 to 50 ppm can cause changes in blood chemistry, and co/ rmoa7 exposure at 100 ppm can cause severe blood disorders. The OSHA exposure limits for benzene vapor are 1 ppm as an 8-hour time-weighted average and a ceiling of 50 ppm for no more than 10 min. In order to reach the level of 10 ppm in a laboratory of 750 m volume, 23 g of liquid benzene would have to evaporate into a closed atmosphere. Thus the hazards associated with the infrequent use of liquid benzene in a well-ventilated laboratory are very low. 

The most important route of asbestos exposure is inhalation, but acute effects are not of primary concern as the major health hazards that are associated with chronic exposure, and can have latencies of more than 30 years. Public health initiatives have therefore focused on reducing initial exposure rather than reducing postexposure absorption. 

No acute effects have been reported in humans. By analogy to effects reported with structurally similar compounds and in animals, cyclohexene is regarded as a mild respiratory irritant and CNS depressant. When ingested, it represents a low to moderate pulmonary aspiration hazard. 

While the emphasis in the 1980 revision of this Standard in defining health hazard is principally upon acute effects, the fire-fighting community is seriously concerned with chronic health effects. Epidemiologic studies demonstrate that firemen pay a significant health toll in protecting society from the devastation of uncontrolled fire. Thus the residual injury that may result from exposure to toxic chemicals or their decomposition and/or combustion products should be a consideration when evaluating health hazard. 

The acute effects referred to most frequently are those defined by the American National Standards Institute (ANSI) standard for Precautionary Labeling of Hazardous Industrial Chemicals (Z129.1-1982)—irritation, corrosivity, sensitization and lethal dose. Although these are important health effects, they do not adequately cover the considerable range of acute effects which may occur as a result of occupational exposure, such as, for example, narcosis. 

A. Acute effects. Because arsine gas is not acutely irritating, inhalation causes no immediate symptoms. Those exposed to high concentrations may sometimes detect a garlic-like odor, but more typically they are unaware of the presence of a significant exposure. In most industrial accidents involving arsine, the hazardous exposure occurred over the course of 30 minutes to a few hours. 

I. Health hazard information. The health hazards section of Table IV-4 focuses primarily on the basic hazards associated with possible inhalation of or skin exposure to chemicals in a workplace. It Is based almost entirely on the occupational health literature. Most of our understanding of the potential effects of chemicals on human health is derived from occupational exposures, the levels of which are typically many times greater than those of environmental exposures. Moreover, the information in Table IV-4 unavoidably emphasizes acute health effects. Much more is known about the acute effects of chemicals on human health than about their chronic effects. The rapid onset of symptoms after exposure makes the causal association more readily apparent for acute health effects. 

Safety hazards related to the physical characteristics of a chemical can be defined in terms of testing requirements, such as ignitability however, health hazard definitions are less precise and more subjective. There have been many attempts to categorize effects and to define them in various ways. Generally, the terms acute and chronic are used to delineate between effects on the basis of severity or duration. Acute effects occur rapidly as a result of short-term exposures. Chronic effects occur as a result of long-term exposures. 

Health hazards. Acute and chronic health hazards are hsted, togetha- with the signs and symptoms of exposure. The primary routes of entry of the substance into the body must also be described. In addition, potential carcinogens are explicitly identified. In some MSDSs, this list of toxic effects is quite lengthy and may include every possible harmful effect the substance can have under the conditions of every conceivable use. 

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