Short-term effects exposures

Short-term effects — Exposure to high concentrations of diesel exhaust may cause these short-term effects irritation of the eyes, nose, and throat dizziness heartbiun headache weakness, numbness, and tingling in the extremities tightness in the chest wheezing and nausea or vomiting. 

Acute Toxicity Studies. These studies should provide the following information the nature of any local or systemic adverse effects occurring as a consequence of a single exposure to the test material an indication of the exposure conditions producing the adverse effects, in particular, information on dose—response relationships, including minimum and no-effects exposure levels and data of use in the design of short-term repeated exposure studies. 

Subchronic Studies. Although short-term repeated exposure studies provide valuable information about toxicity over this time span, they may not be relevant for assessment of ha2ard over a longer time period. For example, the minimum and no-effects levels determined by short-term exposure may be significantly lower if exposure to the test material is extended over several months. Also, certain toxic effects may have a latency which does not allow their expression or detection over a short-term repeated-exposure period for example, kidney dysfunction or disturbances of the blood-forming tissues may not become apparent until subchronic exposure studies are undertaken. 

Primary Irritancy Studies. These studies are employed to determine the potential of materials to cause local inflammatory effects in exposed body surfaces, notably skin and eye, following acute or short-term repeated exposure. In general, the approach involves applying the test material to the surface of the skin or eye, and observing for signs of inflammation, their duration, and resolution. Reviews have been written about the conduct of primary eye irritation (58,86,87) and primary skin irritation studies (88,89). 

Chronic Health Effect A chronic health effect is an adverse health effect resulting from long-term exposure to a substance. The effects could be a skin rash, bronchitis, cancer, or any other medical condition. An example would be liver cancer from inhaling low levels of benzene at your workplace over several years. The term is also applied to a persistent (months, years, or permanent) adverse health effect resulting from a short-term (acute) exposure. Chronic effects from long-term exposure to chemicals are fairly common. Recognize the PEL (permissible exposure level) for each substance in your workplace and minimize your exposure whenever possible. 

Animal studies show effects of methyl parathion similar to those seen in people. In addition, short-term high exposure of animals to methyl parathion caused decreased heart rate. This may be the result of methyl parathion s effects on the nerves that control the heart. Methyl parathion decreased the ability of animals to fight infections in some studies, but not in others. It is not known whether any of these effects occur in people. It is not known whether methyl parathion affects the ability of animals to reproduce. Studies in animals have not shown that methyl parathion causes cancer. 

Most of the materials used in the manufacture of chemicals are poisonous, to some extent. The potential hazard will depend on the inherent toxicity of the material and the frequency and duration of any exposure. It is usual to distinguish between the short-term effects (acute) and the long-term effects (chronic). A highly toxic material that causes immediate injury, such as phosgene or chlorine, would be classified as a safety hazard. Whereas a material whose effect was only apparent after long exposure at low concentrations, for instance, carcinogenic materials, such as vinyl chloride, would be classified as industrial... 

The period of the test depends on whether long- or short-term effects are of interest. Acute toxicity is the effect of a single exposure or a series of exposures close together in a short period of time. Chronic toxicity is the effect of multiple exposures occurring over a long period of time. Chronic toxicity studies are difficult to perform because of the time involved most toxicological studies are based on acute exposures. The toxicological study can be complicated by latency, an exposure that results in a delayed response. 

Filipov, N. M. et al.,. Immunotoxic effects of short-term atrazine exposure in young male C57BL/6 mice, Toxicol. Sci., 86, 324, 2005. 

In environmental exposure tests, the changes in properties are normally monitored at ambient temperature. This is often the case even when the accelerated tests are extrapolated back to an elevated service temperature, rather than to normal ambient. Where the service temperature is elevated the properties should be monitored at that temperature to take into account the short-term effects of temperature on the properties in question. 

A number of effects from breathing phenol in air have been reported in humans. Short-term effects reported include respiratory irritation, headaches, and burning eyes. Chronic effects of high exposures included weakness, muscle pain, anorexia, weight loss, and fatigue effects of chronic low-level exposures included increases in respiratory cancer, heart disease, and effects on the immune system. Virtually all of the workplace exposures associated with these effects involved exposures to other chemicals, thus it is difficult to determine whether these are solely due to phenol, or are the result of mixed, multiple, or other chemical exposures. 

Exposure-response data, using short-term biomarkers or surrogate endpoints, can sometimes make further exposure-response studies from clinical endpoints xmnecessary. For example, if it can be shown that the short-term effect does not increase beyond a particular dose or concentration, there may be no reason to explore higher doses or concentrations in the clinical trials. Similarly, short-term exposure-response studies with biomarkers might be used to evaluate early (i.e., first dose) responses seen in clinical trials. 

Fairchild and Graham, Stokinger et and Stokinger showed that the toxic effect of ozone in experimental animals is cumulative. They found that the effective dose depends on the product of ozone concentration and exposure duration for short-term single exposures. 

The effect of any chemical at a biological target depends on its ability to attain a target site concentration that exceeds the threshold required to ehcit the response. The intensity and duration of the response depends on the toxicokinetic properties of the compound (absorption, distribution, metabolism, and excretion) and the nature of the target site interaction (reversible, irreversible). If recovery is complete between successive exposures, no cumulative toxicity is to be expected. However, a short-term acute exposure could potentially add to the long-term burden of a persistent chemical and be relevant for the magnitude of the chronic effect. 

It should be noted that in humans opportunities for exposure to acutely lethal doses of chlorodibromomethane are remote. In animals, no direct effects of oral exposure to chlorodibromomethane have been noted for the respiratory, cardiovascular, hematologic, or musculoskeletal systems or on the skin or eyes. One study indicated that short-term oral exposure of mice to doses of 125mg/kg/day could produce significant changes in both the humoral and the cell-mediated immune systems. ... 

Savolainen H, Pfaffli P Neurochemical effects of short-term inhalation exposure to vinyltoluene vapor. Arch Environ Contam Toxicol 10 511-517, 1981... 

Solvents are common around the home and workplace. As with most toxic substances, the best policy is to substitute less toxic products whenever possible, and reduce exposure via ventilation or protective equipment if substitutes are not available. Inhalation of solvents is particularly dangerous because of the rapid exchange in the lungs and quick access to the nervous system. Solvent inhalation produces predictable short-term effects but the long-term effects of repeated solvent exposure are not well characterized. 

Immediate versus 24 hr Effects upon Amino Acid Utilization Following Short-Term Ozone Exposure. To work with appreciable differences between control and ozonated discs, the respective seedlings were ozonated for 90 min at 45 5 pphm ozone, and... 

As long as radiation dose equivalent exposures are low, radiation damage is non-detectable. General effects of short-term radiation exposure are summarized in Table 17.5. The dose equivalents in Table 17.5 are listed in rems. These values are several orders of magnitude greater than what humans received in a year. Annual human exposure... 

Description of Effects The health effects resulting from short-term human exposure to food containing specific levels of isophorone are not known. 

LoxCD. 1987. The effects of short term diazinon exposure on blood clotting activity in the rat. J Environ Pathol Toxicol Oncol 7 67-71. 

Since water exposure has been shown 86) to have no substantial short-term effect on adhesive bonds in which a large degree of mechanical interlocking is present, these pretreatments have the potential to enhance the durability of aluminum/polymer adhesion systems. 

Haas-Jobelius, M., Coulston, F. Korte, F. (1992) Effects of short-term inhalation exposure to 1-nitropropane and 2-nitropropane on rat liver enzymes. Ecotoxicol. environ. Saf. 23,253-259... 

Toxicology and Registration. The toxic nature of some dyes and intermediates has lung been recognized. Acute, or short-term, effects are generally well known. They are controlled by keeping the concentration of the chemicals in the workplace atmosphere below prescribed limits and avoiding physical contact with the material. Chronic effects, on the other hand, frequently do not become apparent until after many years of exposure. 

The health effects resulting from short-term human exposure to food containing specific levels of BCME are not known. However, because BCME is rapidly destroyed when it comes into contact with other substances, it is unlikely that BCME would be found in food. 

Animal studies conducted via the inhalation, oral, and dermal routes of exposure for this duration period would be useful since the potential short-term effects of such exposure as well as effects that could emerge years later, such as cancer, are not known. 

Short-term oral exposures to levels of DEHP much higher than those found in the environment interfered with sperm formation in mice and rats. These effects were reversible, but sexual maturity was delayed when the animals were exposed before puberty. Short-term exposures to low levels of DEHP appeared to have no effect on male fertility. 

Few studies have investigated the reproductive toxicity of DEHP in female animals. When female mice were exposed to a dietary dose of 420 mg/kg/day DEHP for 105 days and mated with unexposed males, combined weights of the ovaries, oviducts, and uterus were reduced, and no litters were produced. When female mice exposed to 14 or 140 mg DEHP/kg/day were mated with males given these same doses, there was a dose-related decline in the number of litters, live pups per litter, and live pup weight. Short-term gavage exposure to a very high level of DEHP (2,000 mg/kg/day), particularly with respect to possible human exposure, had clear effects on estradiol synthesis, manifested as decreased serum estradiol levels and anovulatory cycles and polycystic ovaries, in female rats. These data indicate that oral exposure to DEHP can affect reproductive processes in female rodents. 

Acute toxicity The short-term effects of a one-time exposure to a chemical substance. 

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