Toxic agents, classes

According to VNIIGINTOKS, potent toxic agents (PTA), where the fated dose (FD, J is less than 50 mg/ kg, are not introduced into agriculture, are not produced in the USSR, and are not imported from abroad [12]. In actual fact, Risk Class I OPPs with an FD for laboratory animals of less than 50 mg/kg were not only actively used, but were also produced in the USSR for many years (including such OPPs as parathion, demeton, octamethyl pyrophosphoramide, methyl ethyl... 

Epidemiology studies are, of course, useful only after human exposure has occurred. For certain classes of toxic agents, carcinogens being the most notable, exposure may have to take place for several decades before the effect, if it exists, is observable - some adverse effects, such as cancers, require many years to develop. The obvious point is that epidemiology studies cannot be used to identify toxic properties prior to the introduction of a chemical into commerce. This is one reason toxicologists were invented ... 

There is a class of curvilinear dose-response relationships in toxicological and epidemiological studies that may be described as U-shaped or J-shaped curves. Other terms such as biphasic, and more recently hormesis, have been used to refer to paradoxical effects of low-level toxicants. In brief, these dose-response curves reflect an apparent improvement or reversal in the effect of an otherwise toxic agent. These... 

The foregoing toxicity figures must be accepted with reservations, as they apply to one set of conditions only, t.c., to one animal (the cat) and to one rate of breathing. While experimental d(>terminalions of toxicity on animals yield valuable relative data as to certain classes of toxic agents, these data caimot always be applied to man, because... 

It would be unreasonable to study the pharmacokinetics of relatively toxic agents, at potentially therapeutic doses, in normal volunteers due to the near-certainty of the adverse events. Typically, this information can be gained in patients with diseases potentially responsive to these agents. Thus, the first-in-man studies in this case are phase II , using the classic nomenclature. Cytotoxic and antiviral drugs are two important classes of agent where this is commonly the case. 

For clinical purposes, toxic agents can be divided into two classes those for which a specific treatment or antidote exists and those for which there is no specific treatment. For the vast majority of drugs and other chemicals, there is no specific treatment symptomatic medical care that supports vital functions is the only strategy. 

Hyperkalemia usually exacerbates the cardiac toxicity of class I drugs. Treatment of overdose with these agents is often carried out with sodium lactate (to reverse drug-induced arrhjThmiasj and pressor sympathomimetics (to reverse drug-induced hypotension) if indicated. 

There are, therefore, three broad classes of toxic agents -... 

Close liaison between Porton s scientists and expert networks elsewhere in Britain and overseas, essential in maintaining a first-class research facility, was to be assured through the Chemical Warfare Committee, which was broadly representative of the wider scientific, military, and business community. To ensure the coordinated production of toxic agents, including those for testing purposes at Porton, the committee recommended the creation of a state-controlled factory for chemical warfare products at Sutton Oak, near St Helens in Lancashire, which later became the Chemical Defence Research Establishment. A representative of Porton liaised with members of the committee about planned field trials. It was this coordinated approach to chemical warfare through an external body of experts and stakeholders that other nations, the United States and Canada especially, began to emulate. 

One of the first steps by the CWS just before World War II was to expand research on the classes of substances that might be suitable for toxic agents. In this program the National Defense Research Committee did much work. Soon after the committee came into existence in 1940, the CWS submitted to it six projects, four of which were concerned wholly or partially with toxic agents. To screen compounds synthesized by hundreds of chemists in universities and industry, the NDRC established in April 1941 a toxicity laboratory at the University of Chicago. In its four years of existence this laboratory screened about seventeen hundred compounds. The most promising of these, including sulphur fluorides,... 

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