Chronic toxins

Chronic toxicity refers to a chemical s ability to inflict systemic damage as a result of repeated exposures over a prolonged time period, to relatively low levels of the chemical. Some chemicals are extremely toxic and are known primarily as acute toxins (e.g., hydrogen cyanide) some are known primarily as chronic toxins (e.g., lead). Other chemicals, such as some chlorinated solvents, can cause either acute or chronic effects. 

The suitability of arthropods as prey or as hosts of insect predators and parasitoids has been repeatedly shown to be affected by host plant chemistry. The mechanisms by which plant chemical factors mediate suitability of herbivores as hosts (prey) for their natural enemies fall into two broadly overlapping categories. The first involves host plant compounds ingested, and in some cases sequestered, by the herbivores that are toxic or distasteful to parasitoids or predators (4-6). Such compounds may be active as repellents or as acute or chronic toxins ( 5, 7-10). The second category involves the nutritional quality of the host plant mediating herbivore utilization by parasitoids and predators (11-14). Changes in herbivore size due to host plant effects, for example, have been associated with differences in size and sex ratio of parasitoids (13, 12), and differences in functional responses of parasitoids and predators (16). 

Major Hazards Highly flammable chronic toxin affecting the blood-forming organs OSHA "select carcinogen."... 

Major Hazards Chronic toxin affecting the kidneys and central and peripheral nervous systems reproductive and developmental toxin. 

Chronic toxins can cause severe injury after repeated exposure. Examples of chronic toxins include the following ... 

Acute and chronic toxins Irritants Corrosives Sensitizers... 

Usually, it takes years of toxin exposure to cause the pathological alterations seen in COPD. In most cases, the disease is already well-progressed when COPD is diagnosed. Reversal of established chronic inflammatory disease is always extremely difficult to achieve and at present healing of COPD is impossible. Smoking cessation is the single most effective and cost-effective... 

Microbial risks are mostly due to single exposures (except for microbial toxins) chemical risks are affected by chronic duration of exposure. Responses to infective pathogens are probably more variable as compared to chemical agents due to different subpopulations and depending on immune status. 

It has been postulated that Chlamydia may produce a heat shock protein that causes tissue damage through a delayed hypersensitivity reaction. C. trachomatis may also possess DNA evidence of toxin-like genes that code for high-molecular-weight proteins with structures similar to Clostridium difficile cytotoxins, enabling inhibition of immune activation. This may explain the observation of a chronic C. trachomatis infection in subclinical PID. 

Alfano M, Vallanti G, Biswas P, et al. The binding subunit of pertussis toxin inhibits HIV replication in human macrophages and vims expression in chronically infected promonocytic U1 cells. J Immunol 2001 166(3) 1863-1870. 

Jefferys, J. G. Whittington, M. A. (1996). Review of the role of inhibitory neurons in chronic epileptic foci induced by intracerebral tetanus toxin. Epilepsy Res. 26,... 

The TCAs are used most often for prophylaxis of tension headache. Injection of botulinum toxin into pericranial muscles has demonstrated efficacy in prophylaxis of chronic tension-type headache in two studies. 

Infection 1. Invasion and multiplication of microorganisms in body tissues, which may be clinically unapparent or result in local cellular injury due to competitive metabolism, toxins, intracellular replication, or antigen-antibody response. The infection may remain localized, subclinical, and temporary if the body s defensive mechanisms are effective. A local infection may persist and spread by extension to become an acute, subacute, or chronic clinical infection or disease state. A local infection may also become systemic when the microorganisms gain access to the lymphatic or vascular system. 2. An infectious disease. [EU]... 

---