Toxicity irreversible effects

Toxic danger of very serious irreversible effects through inhalation... 

Very toxic danger of very serious irreversible effects through inhalation, in contact with skin and if swallowed... 

Substances, which after very limited exposure cause death or major irreversible effects, even if prompt medical treatment is undertaken. Also included in this category are substances that easily go through protective rubber clothing and those that, under normal conditions or in a fire, release extremely dangerous vapour, whether they are toxic or corrosive by inhalation or skin contact. 

Toxicity endpoint AEGL-2 values were based upon a 3-fold reduction in the AEGL-3 values. This estimate of a threshold for irreversible effects was justified because of the absence of exposure-response data related to irreversible or other serious, long-lasting effects and the steep dose-response relationship indicated by the data that was available on monomethylhydrazine... 

Exposures resulting in nonlethal, irreversible effects of dimethylhydrazine were not well defined. For most studies, responses were described in terms of no visible signs of toxicity or lethality. However, Weeks et al. (1963) described nonlethal (but reversible) effects in dogs exposed to 1,1-dimethylhydrazine at varying concentrations. In this study, dogs were exposed to 1,1-dimethylhydrazine at 1,550 ppm or 4,230 ppm for 5 min or 360, 400, or 1,530 ppm for 15 min. The highest cumulative exposures at each of two exposure periods (Ct =352-383 ppm-h) were associated with marked tremors, convulsions and death, while the lower concentration exposures at each of two periods caused behav... 

Although it is generally considered that response to a toxicant is determined by the availance J Cdt, it must clearly also be expected that there is some threshold of concentration below which the toxicant can be tolerated indefinitely the toxicant arrives so slowly that replacement and repair reactions can compensate for any damage. At the other extreme if the pulse is too rapid the temporary disruption of the vital process may be too short to produce irreversible effects. There is thus likely to be only a defined range of pulse forms producing the specified biological response for any applied dose and since pulse form depends so strongly on P. an optimum value for the partition coefficient within a series of related compounds. 

The nature of an effect includes the adversity of the toxicity expressed as the level of and the basis for NOAEL and LOAEL values (Section 4.2.2), and the severity of the specific endpoint or key event (Section 4.2.3), for example judging skin irritation less severe than teratogenicity. An additional assessment factor for severe and/or irreversible effects has been proposed by various groups. This section gives an overview of such proposals and evaluations. Then, the key issues are summarized and our recommendations are presented. 

An additional assessment factor, of up to 10, has been apphed in some cases where the NOAEL has been derived for a critical effect, which is considered as a severe and irreversible effect, such as teratogenicity or non-genotoxic carcinogenicity, especially if associated with a shallow dose-response relationship. The principal rationale for an additional factor for nature of toxicity has been to provide a greater margin between the exposure of any particularly susceptible humans and the dose-response curve for such toxicity in experimental animals. 

In the EU pure cadmium sulfide is labelled with the symbol T (Toxic) and the Risk phrases 22-40-48/23/25 - Harmful if swallowed. Possible risks of irreversible effects. Toxic Danger of serious damage to health by prolonged exposure by inhalation and if swallowed. 

SUSPECTED CANCER AGENT, EXTREMELY FLAMMABLE, VERY TOXIC BY INHALATION, DANGER OF VERY SERIOUS IRREVERSIBLE EFFECTS... 

Sublethal doses of most toxic substances are eventually eliminated from an organism s system. If there is no lasting effect from the exposure, it is said to be reversible. However, if the effect is permanent, it is termed irreversible. Irreversible effects of exposure remain after the toxic substance is eliminated from the organism. Figure 6.7 illustrates these two kinds of effects. For various chemicals and different subjects, toxic effects may range from the totally reversible to the totally irreversible. 

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