Term Effects

Long-term effects can be divided into three types carcinogenic, teratogenic, and mutagenic. All three types of effects take, from the time of exposure, up to 15 years or longer to develop symptoms. Effects can be aggravated by exposures to other materials or unrelated health problems. 

Teratogens cause one-time birth defects in offspring resulting from maternal or paternal exposure to toxic materials. The word teratology is derived from the Latin meaning the study of monsters. It is actually the study of congenital malformations, which started with the study of the correlation of German measles to birth defects. 

Examples of teratogens include thalidomide, ethyl alcohol, and o-benzoic sulfim-ide (the artificial sweetener saccharin). Thalidomide is a drug that was used in the 1960s as a treatment for morning sickness in pregnant mothers. However, the toxic effects were discovered too late for 10,000 babies who were bom with various malformations. In Japan, where fish is a staple food, mothers ate fish contaminated with mercury compounds, causing children to be bom with cerebral palsy. 

Ethyl alcohol is found in alcoholic beverages and is a known teratogenic material, which is the reason doctors tell pregnant women not to drink alcohol. When a mother drinks, the unborn child drinks as well. Ethyl alcohol causes growth failure and impaired brain development. Unborn children exposed to alcohol may suffer the effects of Eetal Alcohol Syndrome when they are bom. Symptoms of Fetal Alcohol Syndrome include sleep disturbance, jitteriness, a higher incidence of impaired vision and hearing, lack of motor coordination, balance problems, abnormal thyroid function, and a decrease in immune system effectiveness. Additional teratogens include heavy metals, methyl mercury, mercury salts, lead, thallium, selenium, penicillin, tetracyclines, excess Vitamin A, and carbon dioxide. 

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Fig. 10. Long-term effect of aging in vacuum on flexibiUty of Parylenes C, D, and N at elevated temperature. Failure = 50% loss in tensile strength.

Many studies have reported a link between consumption of sunburned potatoes, ie, those exposed to the sun and having an accumulation of chlorophyll and solanine under the skin, with incidences of teratogenic effects and even death (59—61). Because sunburned potatoes in the commercial marketplace are relatively rare, and because the long-term effects of consumption of potatoes at the maximum estabUshed limits of solanine concentration are uncertain, there is equal uncertainty of the tme incidence of human toxicity (62). 

Acute toxicoses, as well as potential long-term effects of aflatoxki ingestion, have been extensively reported (93). Autopsy reports have noted a positive correlation between aflatoxki B and victims of Reye s Syndrome ki Thailand (94), but this evidence should only be considered as suggestive and preliminary (95). 

The long-term effects of CECs and HCECs leaking into the environment have been discussed. Combustion where aU ceUular plastics can evolve smoke containing carbon monoxide and in certain cases cyanide and other toxic gases from various constituents involved in thein manufacture is also a consideration. 

Workers in the metals treatment industry are exposed to fumes, dusts, and mists containing metals and metal compounds, as well as to various chemicals from sources such as grinding wheels and lubricants. Exposure can be by inhalation, ingestion, or skin contact. Historically, metal toxicology was concerned with overt effects such as abdominal coHc from lead toxicity. Because of the occupational health and safety standards of the 1990s such effects are rare. Subtie, chronic, or long-term effects of metals treatment exposure are under study. An index to safety precautions for various metal treatment processes is available (6). As additional information is gained, standards are adjusted. 

For extended, noncyclic exposures, it can be assumed that the entire piece teaches the temperature of the heating medium and is, therefore, subject to permanent strength losses throughout the piece, regardless of size and mode of stress application. Because dry wood is a good insulator, it often does not teach the daily extremes in temperature of the air around it in ordinary constmction thus, estimates of long-term effects should be based on the actual wood temperatures experienced by critical stmctural parts. 

Effects in Humans. In chlorophenol production, irritation symptoms of the nose, eyes, respiratory tract, and skin resulting ia chloroacne have been observed. The results of epidemiology studies on the long-term effects of chlorophenols are quite contradictory and have not allowed the experts to reach any firm conclusions (54). 

Under conditions of normal use, detergent products are not lia2ardous to users. Nonetheless, surfactants possess some toxicity, and they are mild irritants. Particularly under conditions of misuse, such as accidental ingestion or spillage, they can produce irritation and discomfort in the form of nausea and vomiting, as well as irritation to skin and eyes. The long-term effects, however, are minimal (134). 

A cocurrent evaporator train with its controls is illustrated in Fig. 8-54. The control system applies equally well to countercurrent or mixed-feed evaporators, the princip difference being the tuning of the dynamic compensator/(t), which must be done in the field to minimize the short-term effects of changes in feed flow on product quality. Solid concentration in the product is usually measured as density feedback trim is applied by the AC adjusting slope m of the density function, which is the only term related to x. This recahbrates the system whenever x must move to a new set point. 

What Can Be Said About the Long-term Effects of Nitrogen Fertilizer ... 

The full extent of the toxicity of pesticides to aquatic life is not known. Although chronic toxicity testing is required for new substances, little is known about the long-term effects of older pesticides. Also, very little is known about the toxicity and occurrence of the products formed when pesticides break down (metabolites) or the many non-pesticidal additives (co-formulants and adjuvants) used in pesticide formulations. However, the future is looking brighter. New modelling techniques, EQS development, and the involvement of the NRA in the pesticide registration process, coupled with the development of newer, less persistent pesticides with lower dose rates, all should help to reduce the risk of pesticide pollution. 

Nelson, I., Constitutive Models for Use in Numerical Computations, in Proceedings of the Dynamical Methods in Soil and Rock Mechanics, Vol. 2, Plastic and Long-Term Effects in Soils (edited by Gudehus, G.), A.A. Balkema, Rotterdam, 1978, pp. 45-99. 

CFCs represent only one class of chemicals being released to the atmosphere which have long-term effects. Replacement chemicals will be re-... 

Check the toxicity of process materials, identify short and long term effects for various modes of entry into the body and different exposure tolerance Identify the relationship between odour and toxicity for all process materials Determine the means for industrial hygiene recognition, evaluation and control Determine relevant physical properties of process materials under all process conditions, check source and reliability of data... 

Acute (short-term) effects and chronic (long-term) effects. 

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