Monitoring data sources

Source widths, ft Source concentrations, mg/L Zone I Zone 2 105 175 and monitoring data. Source concentrations are... 

Source widths, ft Zone 1 Zone 2 Zone 3 monitoring data. Source... 

A full PSD review would include a case-by-case determination of the controls required by BACT, an ambient air-impacd analysis to determine whether the source might violate applicable increments or air-quahty standards an assessment of the effecd on visibihty soils, and vegetation submission of monitoring data and full public review. 

Thus, tlie focus of tliis subsection is on qualitative/semiquantitative approaches tliat can yield useful information to decision-makers for a limited resource investment. There are several categories of uncertainties associated with site risk assessments. One is tlie initial selection of substances used to characterize exposures and risk on tlie basis of the sampling data and available toxicity information. Oilier sources of uncertainty are inlierent in tlie toxicity values for each substance used to characterize risk. Additional micertainties are inlierent in tlie exposure assessment for individual substances and individual exposures. These uncertainties are usually driven by uncertainty in tlie chemical monitoring data and tlie models used to estimate exposure concentrations in tlie absence of monitoring data, but can also be driven by population intake parameters. As described earlier, additional micertainties are incorporated in tlie risk assessment when exposures to several substances across multiple patliways are suimned. 

The second improvement comes from the potential that computers have, in conjunction with newer processes, to dramatically reduce the cost and time required to monitor data. Most of monitoring involves comparing a source document, defined as the first place a piece of data was recorded, with what was written. Because data are often recorded by first entry in a patient record,... 

This review begins with a summary of the sources of monitoring data operated primarily by public agencies. The spatial and temporal patterns of oxidant concentrations are then discussed—urban versus rural and indoor versus outdoor relationships, diurnal and seasonal patterns, and long-term trends. The chapter includes brief discussions of photochemical oxidants other than ozone and of data quality and concludes with a set of recommendations for guidelines in future monitoring of atmospheric concentrations of ozone and other photochemical oxidants. 

In general, cresols will degrade in surface waters very rapidly. However, cresols may persist in groundwater due to a lack of microbes and/or anaerobic conditions. Cresols are largely released to groundwater via landfills and hazardous waste sites. Tables 5-2a through 5-2e include monitoring data for these sources. 

Monitoring data have not shown cresols to be widely occurring atmospheric pollutants. The National Ambient Volatile Organic Compounds (VOCs) Database, a compilation of published and unpublished air monitoring data from 1970 to 1987, contained very little information on the cresols (Shah and Heyerdahl 1989). The database contained only information for o-cresol in source-dominated atmospheres (air surrounding a facility or known release of the chemical in question). The median air concentration of o-cresol at source-dominated sites is 0.359 ppb for 32 samples (Shah and Heyerdahl 1989). 

The most common route of exposure for the general population is probably inhalation. However, cresols have a short residence time in both day- and night- time air despite continual releases of cresols to the atmosphere, levels are probably low. Very few atmospheric monitoring data are available in the literature therefore, an average daily intake via inhalation was not calculated. Cigarette smoke is also a source of atmospheric exposure. An individual who smokes two packs of cigarettes a day may inhale 3.0 pg/day (Wynder and Hoffman 1967). 

Sunderman (1993) reviewed all the biologieal monitoring data for niekel in humans and eoneluded that the most use l speeimens for biologieal monitoring are urine and semm. Levels of nickel in urine and serum ean provide the most information about levels of nickel exposure if the route, sources, and duration of exposure are known, if the ehemical identities and physical-chemieal properties of the nickel eompounds are known, and if physiologieal information, for example renal ftmetion, of the exposed population is known (Sunderman 1993). 

Nickel releases to the atmosphere are mainly in the form of aerosols that cover a broad spectrum of sizes. Particulates from power plants tend to be associated with smaller particles than those from smelters (Cahill 1989 Schroeder et al. 1987). Atmospheric aerosols are removed by gravitational settling and dry and wet deposition. Submicron particles may have atmospheric half-lives as long as 30 days (Schroeder et al. 1987). Monitoring data confrrm that nickel can be transported far from its source (Pacyna and Ottar 1985). Nickel concentrations in air particulate matter in remote, rural, and U.S. urban areas are 0.01-60, 0.6-78, and 1-328 ng/m, respectively (Schroeder et al. 1987). 

For assessing the risks of chemicals, the approach is similar to that used with radiation in those cases where human data are available, but the data are rarely as complete as with radiation. Furthermore, estimation of the dose is usually more difficult with chemicals because of the lack of good monitoring data and other sources of uncertainty (see Section 5). For example, the dose is not usually well quantified even at levels of exposure where carcinogenic effects are conspicuous. 

Monitoring data indicated that the levels of PBDEs are increasing in freshwater aquatic organisms with higher concentrations near point sources. The congener profiles show the highest levels for BDE-47. 

In-process monitoring of critical processing steps and end-product testing of current production can provide documented evidence to show that the manufacturing process is in a state of control. Such validation documentation can be provided from the test parameter and data sources disclosed in the section on retrospective validation. 

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