National Contaminant Occurrence

The National Contaminant Occurrence Database, which stores data on the occurrence of both regulated and unregulated materials, was established by EPA. The monitoring data provides the basis for identifying contaminants that may be placed on future Contaminant Candidate Lists and support the Agency s decisions to regulate contaminants in the future. 

EPA. 2000c. National drinking water contaminant occurrence query user s guide. National contaminant occurrence database. U.S. Environmental Protection Agency. 

Overall there appears to be considerable uniformity in the concentration of di- -butyl phthalate in the surface waters of the United States, if locally contaminated areas are excluded. The National Drinking Water Contaminant Occurrence Database (NDOD), which contains data from ambient water samples, lists... 

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. 

Testa, S. M., 1990, Light Non-Aqueous Phase Liquid Hydrocarbon Occurrence and Remediation Strategy, Los Angeles Coastal Plain, California In Proceedings of the International Association of Hydrogeologists, Canadian National Chapter, on Subsurface Contamination by Immiscible Fluids, April, in press. 

US-EPA sets national standards for tap water, which help ensure consistent quality in the water supply. US-EPA prioritizes contaminants for potential regulation based on risk and how often they occur in water supplies. Certain water systems are monitored for the presence of contaminants for which no national standards currently exist and collect information on their occurrence. US-EPA sets a health goal based on risk, including risks to the most sensitive people, e.g., infants, children, pregnant women, the elderly, and the immuno-compromised. US-EPA then sets a legal limit for the... 

Disinfection by-products (DBPs) form an undesired species in the chlorine disinfection processes of waters (performed with chlorine, chlorine dioxide, and chloramines). The high priority DBPs include brominated, chlorinated, and iodinated species of halomethanes, brominated, and chlorinated forms of haloacetonitriles, haloketones, haloacids, and halonitromethanes, as well as analogues of 3-chloro-(4-dichloromethyl)-5-hydroxy-2(5//)-furanone. All the high priority DBPs included in the Nation-wide DBP occurrence study are listed in Table 18.1 together with other contaminants. 

The first national-scale study of emerging contaminants in the United States found that such compounds were commonly present in stream systems, with 80% of the streams sampled having at least one compound detected [11]. Over 60% of the chemical concentrations exceeding 1 xg/L were from three detergent metabolites (4-nonylphenol, 4-nonylphenol monoethoxylate, and 4-nonylphenol diethoxylate). In addition, transformation products also were frequently detected (e.g., cotinine, 1,7-dimethylxanthine, erythromycin H2O). This study indicated the enormous potential for parent compoimds to degrade during environmental transport and for the transformation products to contribute much of the relative loading of these contaminants. The results confirm the need to include both parent compoimds and transformation products in occurrence studies. 

National Occurrence Data Base and the Unregulated Contaminant Monitoring Rule Prevention approaches... 

SDWA has provisions that provide for the collection, organization and sharing of occurrence data on contaminants of potential concern. The National Drinking Water... 

National and transnational regulatory frames, improved awareness of health- and quality-related issues, and growing occurrence among the general population of adverse reactions toward some food components have increased the need for specific and sensitive methods capable of assessing specific food constituents, as well as additives, adulterants, and contaminants. 

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