Health effects levels

All input parameters, scenario definitions and results are stored in a database for easy access and retrieval. Analysis of individual scenario results and statistical analysis over all scenarios (or any subset) is possible. Typical individual scenario results are deposition, dosage and casualty level on the attacked target. Typical statistical analysis results are dosage and deposition threat spectra, and casualty spectra. The casualty levels and spectra can be obtained for various health effect levels (eye effect, incapacitation, lethal) and protection levels (no protection, suit only, mask only, mask and suit, collective protection). This model thus largely eliminates the subjectivity involved in scenario studies, protective and detector equipment procurement. 

Health effect Levels of CDD and CDF in breast milk (ng TEQ/kg milk fat) Reference... 

A minimal risk level (MRL) is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration and route of exposure. These substance-specific estimates, which are intended to serve as screening levels, are used by ATSDR health assessors and others to identify contaminants and potential health effects thai may be of concern at hazardous waste sites. The chronic-duration oral MRL of 1 picogram/kilogram/day or pg/kg/day for TCDD, or total TEQs, (ATSDR 1999) was based on neurobehavioral effects in monkeys. Based on this value, an EMEG of 50 ppt (0.05 ppb) TCDD, which is equivalent to 50 ppt (0.05 ppb) TEQs, was derived for exposure from contaminated soil. Uncertainty factors of 90 (total) were used in the calculations of the MRL (for further details, see ATSDR 1999). Based on a review of more recent literature, ATSDR scientists conclude that the MRL of 1 pg/kg/day is approximately two orders of magnitude below the noncancer health effect levels observed in recent studies. This is also true for cancer effect levels. 

As noted previously, ATSDR s EMEG is based on the MRL of 1 pg/kg/day TCDD, which is approximately two orders of magnitude below any health effect levels demonstrated either... 

In some cases the limit applies to the raw water, in others to the water at the point of use, although a clear distinction is not always made, txhe higher limit is for water in contact with lead pipes for 16 h. txhe US National Academy of Science state The no-observed-adverse-health-effect level cannot be set with assurance at any value greater than 0.025 mg dm" . 

The health effects of sorbic acid and sorbates have been reviewed (165—167). The extremely low toxicity of sorbic acid enhances its desirabiHty as a food preservative. The oral LD q for sorbic acid in rats is 7—10 g/kg body weight compared to 5 g/kg for sodium chloride (165—169). In subacute and chronic toxicity tests in rats, 5% sorbic acid in the diet results in no abnormal effects after 90 days or lifetime feeding studies. A level of 10% in rat diets results in a slight enlargement of the Hver, kidneys, and thyroid gland (170). This same dietary level fed to mice also resulted in an increase in Hver and kidney weight... 

Early applications of crystalline fructose focused on foods for special dietary applications, primarily calorie reduction and diabetes control. The latter application sought to capitalize on a signiftcandy lower serum glucose level and insulin response in subjects with noninsulin-dependent diabetes melUtus (21,22) and insulin-dependent diabetes (23). However, because fmctose is a nutritive sweetener and because dietary fmctose conversion to glucose in the hver requires insulin in the same way as dietary glucose or sucrose, recommendations for its use are the same as for other nutritive sugars (24). Review of the health effects of dietary fmctose is available (25). 

Health and Safety Factors. Carbonyl sulfide is dangerously poisonous, more so because it is practically odorless when pure. It is lethal to rats at 2900 ppm. Studies show an LD q (rat, ip) of 22.5 mg/kg. The mechanism of toxic action appears to iavolve breakdowa to hydrogea sulfide (36). It acts principally on the central nervous system with death resulting mainly from respiratory paralysis. Little is known regarding the health effects of subacute or chronic exposure to carbonyl sulfide a 400-p.g/m max level has been suggested until more data are available (37). Carbon oxysulfide has a reported inhalation toxicity in mice LD q (mouse) = 2900 ppm (37). 

Zinc is also an essential food element in the human diet. Too Httle zinc in the diet can lead to poor health, reproductive problems and a lowered abHity to resist disease. Taking too much zinc into the body through food, water or dietary supplements can also affect health. The levels of zinc that produce adverse effects are higher than the Recommended DaHy AHowances, which are 15 mg/day for men, 12 mg/day for women, 10 mg/day for children and 5 mg/day for infants. 

Human Health Effects. Any assessment of adverse human health effects from PCBs should consider the route(s) of and duration of exposure the composition of the commercial PCB products, ie, degree of chlorination and the levels of potentially toxic PCDF contaminants. As a result of these variables, it would not be surprising to observe significant differences in the effects of PCBs on different groups of occupationally-exposed workers. 

Environmental exposures to PCBs are significantly lower than those reported in the workplace and are therefore unlikely to cause adverse human health effects in adults. However, it is apparent from the results of several recent studies on children that there was a correlation between in utero exposure to PCBs, eg, cord blood levels, and developmental deficits (65—68) including reduced bkth weight, neonatal behavior anomaUes, and poorer recognition memories. At four years of age, there was stiU a correlation between prenatal PCB exposure levels and short-term memory function (verbal and quantitative). In these studies the children were all exposed to relatively low environmental levels of PCBs. Although these effects may be related to other contaminants, it is clear that this is an area of concern regarding the potential adverse human health impacts of PCBs. 

Polymers. Studies to determine possible exposure of workers to residual epichl orohydrin and ethylene oxide monomers in the polymers have been done. Tests of warehouse air where Hydrin H and Hydrin C are stored showed epichl orohydrin levels below 0.5 ppm. Air samples taken above laboratory mixing equipment (Banbury mixer and 6" x 12" mill) when compounds of Hydrin H or C were mixed gave epichl orohydrin levels below detectable limits, and ethylene oxide levels less than 0.2 ppm, well below permissible exposure limits (46). A subacute vapor inhalation toxicity study in which animals were exposed to emission products from compounded Parel 58 suggests that no significant health effects would be expected in workers periodically exposed to these vapors (47). 

The results from the consequence analysis step are estimates of the statistically expected exposure of the target population to the hazard of interest and the safety/health effects related to that level of exposure. For example ... 

Comparison of Pollutant Standard Index (PSD Values, Pollutant Levels, and General Health Effects... 

Summary of Lowest Observed Effect Levels for Key Lead-Induced Health Effects in Adults... 

The main objective of air quality guidelines and standards is the protection of human health. Since fme particulates (PM,) are more likely to cause adverse health effects than coarse particulates, guidelines and standards referring to fine particulate concentrations are preferred to those referring to TSP, which includes coarse particulate concentrations. Scientific studies provide ample evidence of the relationship between exposure to short-term and long-term ambient particulate concentrations and human mortality and morbidity effects. However, the dose-response mechanism is not yet fully understood. Furthermore, according to the WHO, there is no safe threshold level below which health damage does not occur. 

Health effects attributed to sulfur oxides are likely due to exposure to sulfur dioxide, sulfate aerosols, and sulfur dioxide adsorbed onto particulate matter. Alone, sulfur dioxide will dissolve in the watery fluids of the upper respiratory system and be absorbed into the bloodstream. Sulfur dioxide reacts with other substances in the atmosphere to form sulfate aerosols. Since most sulfate aerosols are part of PMj 5, they may have an important role in the health impacts associated with fine particulates. However, sulfate aerosols can be transported long distances through the atmosphere before deposition actually occurs. Average sulfate aerosol concentrations are about 40% of average fine particulate levels in regions where fuels with high sulfur content are commonly used. Sulfur dioxide adsorbed on particles can be carried deep into the pulmonary system. Therefore, reducing concentrations of particulate matter may also reduce the health impacts of sulfur dioxide. Acid aerosols affect respiratory and sensory functions. 

In nonindustrial settings, MCS substances are the cause of indoor air pollution and are the contaminants in air and water. Many of the chemicals which trigger MCS symptoms are known to be irritants or toxic to the nervous system. As an example, volatile organic compounds readily evaporate into the air at room temperature. Permitted airborne levels of such contaminants can still make ordinary people sick. When the human body is assaulted with levels of toxic chemicals that it cannot safely process, it is likely that at some point an individual will become ill. For some, the outcome could be cancer or reproductive damage. Others may become hypersensitive to these chemicals or develop other chronic disorders, while some people may not experience any noticeable health effects. Even where high levels of exposure occur, generally only a small percentage of people become chemically sensitive. 

The threshold for toxic injury is not the same for everyone because sensitivity varies greatly among individuals. Most chemicals in consumer products remain untested for health effects, such as cancer, reproductive problems, and the impacts of long-term, low level exposure. How these substances affect women, children, and people with existing conditions is also little studied. Once a person s defenses have been broken down and he or she has become hypersensitive, a wide variety of common chemical exposures can trigger a reaction. Just what products and other chemicals which cause problems varies greatly among affected individuals. 

Indoor air often contains a variety of contaminants at concentrations that are far below any standards or guidelines for occupational exposure. Given our present knowledge, it is difficult to relate complaints of specific health effects to exposures to specific pollutant concentrations, especially since the significant exposures may be to low levels of pollutant mixtures. 

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. 

EPA must first make determinations about which contaminants to regulate. These determinations are based on health risks and the likelihood that the contaminant occurs in public water systems at levels of concern. The National Drinking Water Contaminant Candidate List (CCL), published March 2, 1998, lists contaminants that (1) are not already regulated under SDWA (2) may have adverse health effects (3) are known or anticipated to occur in public water systems and (4) may require regulations under SDWA. Contaminants on the CCL are divided into priorities for regulation, health research and occurrence data collection. 

Microbial Contaminants For microbial contaminants that may present public health risk, the MCLG is set at zero because ingesting one protozoa, virus, or bacterium may cause adverse health effects. EPA is conducting studies to determine whether there is a safe level above zero for some microbial contaminants. So far, however, this has not been established. 

The hazards of chemicals are commonly detected in the workplace first, because exposure levels there are higher than in the general environment. In addition, the exposed population is well known, which allows early detection of the association between deleterious health effects and the exposure. The toxic effects of some chemicals, such as mercury compounds and soot, have been known already for centuries. Already at the end of the eighteenth century, small boys who were employed to climb up the inside of chimneys to clean them suffered from a cancer of the scrotum due to exposure to soot. This was the first occupational cancer ever identified. In the viscose industry, exposure to carbon disulfide was already known to cause psychoses among exposed workers during the nineteenth century. As late as the 1970s, vinyl chloride was found to induce angiosarcoma of the liver, a tumor that was practically unknown in ocher instances. ... 

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