Long-term effectiveness

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). 

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. 

The number of cancers over the next 70 years firom this exposure, was estimated using the conservative linear model to be 160 which should be compared with 27,000 cancers the evacuees will get from natural causes over 70 years. Thus, the long-term effect of the accident will be... 

Beryllium Be High toxicity, long-term effects... 

TCDD is the most potent inducer of chloracne. This has been well known since the accident in Seveso, Italy, in 1976 in which large amounts of TCDD were distributed in the environment subsequent to an explosion in a factory that produced a chlorophenoxy herbicide, 2,4,5-T. TCDD is an impurity produced during the production of 2,4,5-T. The most common long-term effect of TCDD exposure was chloracne. Exposed individuals also suffered increased excretion of porphyrins, hyper-pigmentation, central nervous system effects, and liver damage and increased risk of cancer was a long-term consequence of the exposure. In addition to TCDD, polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans, and polychloronaphthalens cause chloracne as well as other effects typical of TCDD. 7i... 

After the use of a chemical becomes widespread, new deleterious effects on human health may be observed. In such situations, the occupational limit values will have to be modified. Usually the OELS tend to decrease when more information on the toxicity of a chemical is obtained. Knowledge of the specific features of various chemicals is thus extremely important for planning ventilation of industrial premises. It is important to be especially aware of those chemicals that may cause long-term effects without causing any acute effects. There are also compounds such as isocyanates that are extremely irritating at concentrations as low as 0.5 ppm. However, some workers may become sensitized to isothiocyanates at a concentration of 10 ppb, and therefore this has to be taken into consideration when planning the industrial ventilation. Thus, one has to plan against compounds that can cause serious health effects at concentrations at which their presence cannot be observed by the human senses, i.e., irritation or odor. 

The necessary containment or transport capability of a local ventilation sy stem depends on the type of contaminant present and its health risks. There could be different demands for gases and particles, for contaminants that have immediate health risks and those that have long-term effects, for contaminants that affect the breathing system and those that affect the skin and eyes, for infectious contaminants, fot contaminants that follow the air streamlines closely and those that fall out on floor and work surfaces, etc. (See Chapter 5 for physiological and toxicological considerations.)... 

Since the resources for data collection systems will be provided by senior management it is essential that information from the system is fed back to policy makers at this level. It is also important that the system indicates the problem areas as well as the successes. Many organizations have drifted to a state where safety standards have fallen to below acceptable levels over time as a result of suppression of information feedback to senior managers. This may be carried out with good intentions, but its long-term effect can be disastrous. 

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