Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Exposure analysis estimating intakes

Exposure analysis. The amount of any chemical that an individual is exposed to will depend upon the levels that occur in food and the amounts of those foods that are consumed. Different population groups will often have different levels of exposure and it is therefore necessary to identify such sub-groups. The exposure level for additives is frequently referred to as the Estimated Daily Intake (EDI). [Pg.61]

Pharmacokinetic calculations yielded estimates of chlorpyrifos intake of 0.05-1 pg/kg per day in the general population. The model estimates compare favorably with pathway analysis estimates of aggregate chlorpyrifos exposure from numerous dose routes, including indoor inhalation, dermal contact, and food ingestion (Shurdut et al. 1998 Pang et al. 2002). The calculated exposure doses ranged from 0.02 to 1 pg/kg per day. Further... [Pg.295]

As an alternative to the assumption of a one-time exposure for 1,000 h at the time of facility closure, permanent occupancy of a disposal site following loss of institutional control could be assumed (see Section 7.1.3.4). The assumption of chronic lifetime exposure would affect the analysis for hazardous chemicals that induce deterministic effects only if estimated intakes due to additional pathways, such as consumption of contaminated vegetables or other foodstuffs produced on the site, were significant. Based on the results for lead in Table 7.8, an intake rate from additional pathways of about 50 percent of the assumed intake rate by soil ingestion, inhalation, and dermal absorption would be sufficient to increase the deterministic risk index above unity. The importance of additional pathways was not investigated in this analysis, but they clearly would warrant consideration. The increase in exposure time during permanent occupancy does not otherwise affect the analysis for chemicals that induce deterministic effects, provided RfDs are appropriate for chronic exposure, because chronic RfDs incorporate an assumption that the levels of contaminants in body organs relative to the intake rate (dose) are at steady state. [Pg.345]

Although the advice is given mainly for the description of risk assessment results, it holds completely for exposure assessment, since the quantitative input for risk assessment is exposure assessment and uncertainty analysis. Since any description of the resulting exposure distribution(s) in terms such as very low , low , fair , moderate , high or extreme includes an evaluation, it must be defined and justified (EnHealth Council, 2004). Those communicating the results of an exposure assessment frequently use comparative reporting schemes, such as the 50%/majority/. .. /95% of data/measurements/individuals show exposure values/estimates/measurements lower than the tolerable daily intake... [Pg.75]

The four steps of the risk-assessment process are hazard identification, analysis of exposure, analysis of effect, and risk characterization. In the hazard identification step, the risk assessor identifies chemicals of concern, environmental pathways of exposure, and populations and subpopulations at risk. The exposure analysis develops exposure scenarios and estimates the chronic daily intake of each chemical of concern. In the analysis of effect, the risk assessor combines the chronic daily intake calculated in the exposure analysis with toxicity data from animal studies (and/or human epidemiological studies, if available) to estimate the risk of toxic effects in exposed populations, whereby risks to public health are divided into two broad categories noncancer health effects and cancer. The final step of the risk-assessment process, risk characterization, is a narrative that marshals all the evidence of risk to public health, including quantitative risk assessments and qualitative evidence of risk. The risk assessor weighs all the evidence and uses professional judgment to draw conclusions about risks. [Pg.151]

Let us take a closer look at the analysis of exposnre to a toxic chemical. If the ecological receptor is a population of fish, such as coho salmon, a useful measure of exposure is the concentration of the toxic chemical in water. If the ecological receptor is a population of birds, exposure analysis is performed in much the same way as the estimate of chronic daily intake in a human health risk assessment (Chapter 8). The measure of interest is the average daily dose (ADD) in units of milligrams of... [Pg.163]

The purpose of an Exposure Route and Receptor Analysis is to provide methods for estimating individual and population exposure. The results of this step combined with the output of the fate models serve as primary input to the exposure estimation step. Unlike the other analytic steps, the data prepared in this step are not necessarily pollutant-specific. The two discrete components of this analysis are (1) selection of algorithms for estimating individual intake levels of pollutants for each exposure pathway and (2) determination of the regional distribution of study area receptor populations and the temporal factors and behavioral patterns influencing this distribution. [Pg.292]

Risk characterization is thus the step in the risk assessment process where the outcome of the exposure assessment (e.g., daily intake via food and drinking water, or via inhalation of airborne substances) and the hazard (effects) assessment (e.g., NOAEL and tolerable intake) are compared. If possible, an uncertainty analysis should be carried out, which produces an estimation of the risk. Several questions should be answered before comparison of hazard and exposure is made ... [Pg.346]

To illustrate the application of 2nd-order Monte Carlo analysis, we estimated exposure of Carolina wrens to a hypothetical pesticide in cotton fields in the southwest United States. For this case study, the pesticide is assumed to be persistent, and the goal is to estimate chronic exposure (i.e., total daily intake) at the local field scale. The input data are representative of the kinds of data available during reregistration but, for this case study, are entirely hypothetical. [Pg.128]

In addition, existing databases where environmental media and biomonitoring data are collected (such as NHEXAS) could be further studied to estimate exposure and explore the relationships between biomarker concentration and exposure. That information can be used to apportion chemical intake into the different exposure pathways to assist in interpreting population variability, to calculate exposure by combining environmental measurements with survey information to verify estimates of exposure from pharmacokinetic models, and to identify research needs on the basis of discrepancies between estimates obtained from the exposure-pathways analysis and biomonitoring results. [Pg.269]

Exposure to indoor hydrocarbon vapors can occur as a consequence of changes of land use from commercial or industrial to residential. Residual hydrocarbons in soils or groundwater may result in a chronic vapor exposure pathway. Analysis of risk associated with exposure to hydrocarbons typically is undertaken in a multi-step approach known as risk assessment. A thorough discussion of the use of risk assessment at contaminated sites is provided in Chapter 9.01. Assessing risks posed by hydrocarbon spills or wastes is complex and involves estimates of chemical concentrations at each potential exposure point, identification of the potential populations that may be exposed, and assessment of exposure pathways, intake rates, and the toxicity of the chemicals of concern. [Pg.4979]

An analysis of 203 workers with internal deposits of plutonium showed that 131 were contaminated by inhalation, 48 through wounds, and eight by both routes. Most exposures to the general population involve minute quantities inhaled with ambient air or ingested in food and water. In the 1970s, a mean dietary intake of 1.6 pCi year was estimated for New York City. [Pg.2035]

The diet in the two studies was also considerably different. The majority of the mercury exposure to the Faroe Island population came from whale meat (estimated at about 3 ppm in muscle tissue) with a relatively small portion coming from fish. Some of the mercury in whale meat is in the form of inorganic mercury. In the Seychelles study, all of the mercury came from fish as methylmercury with concentrations of around 0.3 ppm. Whale meat blubber is widely consumed in the Faroe Islands and also contains polychlorinated biphenyls (PCBs). Grandjean et al. (1995b) estimated a daily intake of 200 g of PCB. This value can be compared to the Tolerable Daily Intake of PCBs established by the FDA of 60-70 g/day for an adult. Further statistical analysis of the possible influence of PCBs on the observed study results needs to be conducted (see the discussion below on Peer Panel IReview of Kev Studies for additional comments). [Pg.269]


See other pages where Exposure analysis estimating intakes is mentioned: [Pg.278]    [Pg.196]    [Pg.339]    [Pg.500]    [Pg.4548]    [Pg.2681]    [Pg.938]    [Pg.6]    [Pg.138]    [Pg.19]    [Pg.192]    [Pg.123]    [Pg.362]    [Pg.233]    [Pg.309]    [Pg.16]    [Pg.191]    [Pg.195]    [Pg.294]    [Pg.240]    [Pg.495]    [Pg.498]    [Pg.516]    [Pg.28]    [Pg.618]    [Pg.399]    [Pg.69]    [Pg.23]    [Pg.59]    [Pg.142]    [Pg.341]    [Pg.1222]    [Pg.80]    [Pg.137]    [Pg.109]   
See also in sourсe #XX -- [ Pg.67 , Pg.68 , Pg.69 , Pg.70 , Pg.71 , Pg.72 , Pg.73 , Pg.74 ]

See also in sourсe #XX -- [ Pg.6 , Pg.24 ]




SEARCH



Exposure analysis

Exposure estimates

Exposure estimating

Exposure estimation

Intake estimates

© 2024 chempedia.info