Levels of antibiotic resistance genes in manure, biosolids, and fertilized soil

Increasing antibiotic resistance genes in the environment may pose a threat to public health. In this study, tetracycline and sulfonamide resistance genes (Tet-W, Tet-O, and Sul-I) were quantified in 24 manure samples from three farms and 18 biosolids samples from seven different wastewater treatment plants using quantitative polymerase chain reaction methods. Concentrations of Tet-W and Tet-O genes were observed to be significantly higher (p < 0.05) in manure than in biosolids samples. The background soil samples showed significantly lower concentration of the above genes compared with manure and biosolids. Lime-stabilized biosolids showed significantly (p < 0.05) lower concentration of antibiotic resistance genes compared with other biosolids treatment methods. Elevated levels of antibiotic resistance genes (Tet-W, Tet-O, and Sul-I) were observed in the amended soil samples after the land application of manure or biosolids (Site A) monitored for a period of about 4 mo. However, at another site (Site B), no significant increase (p > 0.05) in concentration of antibiotic resistance genes was observed after biosolids application on soil. Even though the concentration of antibiotic resistance genes in manure was statistically higher than that in biosolids, when they were applied on land, the contribution to the soil depended on the background soil concentration and the soil characteristics. Further study of multiple soil samples in various locations is needed.     

Processes for managing pathogens

Wastewater contains human, animal, and plant pathogens capable of causing viral, bacterial, or parasitic infections. There are several routes whereby sewage pathogens may affect human health, including direct contact, contamination of food crops, zoonoses, and vectors. The range and numbers of pathogens in municipal wastewater vary with the level of endemic disease in the community, discharges from commercial activities, and seasonal factors. Regulations to control pathogen risk in the United States and Europe arising from land application of biosolids are based on the concept of multiple barriers to the prevention of transmission. The barriers are (i) treatment to reduce pathogen content and vector attraction, (ii) restrictions on crops grown on land to which biosolids have been applied, and (iii) minimum intervals following application and grazing or harvesting. Wastewater treatment reduces number of pathogens in the wastewater by concentrating them with the solids in the sludge. Although some treatment processes are designed specifically to inactivate pathogens, many are not, and the actual mechanisms of microbial inactivation are not fully understood for all processes. Vector attraction is reduced by stabilization (reduction of readily biodegradable material) and/or incorporation immediately following application. Concerns about health risks have renewed interest in the effects of treatment (on pathogens) and advanced treatment methods, and work performed in the United States suggests that Class A pathogen reduction can be achieved less expensively than previously thought. Effective pathogen risk management requires control to the complete chain of sludge treatment, biosolids handling and application, and post-application activities. This may be achieved by adherence to quality management systems based on hazard analysis critical control point (HACCP) principles.     

Biosolids-derived nitrogen mineralization and transformation in forest soils

Utilization of biosolids through land application is becoming increasingly popular among wastewater managers. To minimize the potential contamination of receiving waters from biosolids-derived nitrogen (N), it is important to understand the availability of N after land application of biosolids. In this study, four secondary biosolids (two municipal and two pulp and paper industrial biosolids) were used in a laboratory incubation experiment to simulate N mineralization and transformation after land application. Municipal biosolids were from either aerobically or anaerobically digested sources, while pulp and paper industrial biosolids were from aerated wastewater stabilization lagoons. These biosolids were mixed with two New Zealand forest soils (top 100 mm of a volcanic soil and a brown soil) and incubated at two temperatures (10 and 20 degrees C) for 26 wk. During incubation, mineralized N was periodically leached from the soil-biosolids mixture with 0.01 M CaCl2 solution and concentrations of NH4 and NO3 in leachate were determined. Mineralization of N from aerobically digested municipal biosolids (32.1%) was significantly more than that from anaerobically digested biosolids (15.2%). Among the two pulp and paper industrial biosolids, little N leached from one, while as much as 18.0% of total organic N was leached from the other. As expected, mineralization of N was significantly greater at 20 degrees C (average 22.8%) than at 10 degrees C (average 9.7%). It was observed that more N in municipal biosolids was mineralized in the brown soil, whereas more N in pulp and paper industrial biosolids mineralized in the volcanic soil. Transformation of NH4 to NO3 was affected by soil type and temperature.     

Estimated occupational risk from bioaerosols generated during land application of class B biosolids

Some speculate that bioaerosols from land application of biosolids pose occupational risks, but few studies have assessed aerosolization of microorganisms from biosolids or estimated occupational risks of infection. This study investigated levels of microorganisms in air immediately downwind of land application operations and estimated occupational risks from aerosolized microorganisms. In all, more than 300 air samples were collected downwind of biosolids application sites at various locations within the United States. Coliform bacteria, coliphages, and heterotrophic plate count (HPC) bacteria were enumerated from air and biosolids at each site. Concentrations of coliforms relative to Salmonella and concentrations of coliphage relative to enteroviruses in biosolids were used, in conjunction with levels of coliforms and coliphages measured in air during this study, to estimate exposure to Salmonella and enteroviruses in air. The HPC bacteria were ubiquitous in air near land application sites whether or not biosolids were being applied, and concentrations were positively correlated to windspeed. Coliform bacteria were detected only when biosolids were being applied to land or loaded into land applicators. Coliphages were detected in few air samples, and only when biosolids were being loaded into land applicators. In general, environmental parameters had little impact on concentrations of microorganisms in air immediately downwind of land application. The method of land application was most correlated to aerosolization. From this large body of data, the occupational risk of infection from bioaerosols was estimated to be 0.78 to 2.1%/yr. Extraordinary exposure scenarios carried an estimated annual risk of infection of up to 34%, with viruses posing the greatest threat. Risks from aerosolized microorganisms at biosolids land application sites appear to be lower than those at wastewater treatment plants, based on previously reported literature.     

Phosphorus release from a biosolids-amended sandy spodosol

Most regulations governing biosolids land application do not consider that phosphorus (P) solubility can vary widely among biosolids. Current regulations typically group all biosolids together in one category or group biosolids together with manures. Research has shown that not all biosolids have the same potential to affect the environment when land applied, but the database is limited. The purpose of this study was to characterize P release from several biosolids produced and/or marketed in Florida. A small soil column dynamic laboratory incubation was conducted to assess P release potential. Eleven biosolids and a mineral fertilizer (triple super phosphate) were individually mixed with a typical low-P sorbing Florida soil (Immokalee fine sand) at 56 and 224 kg P ha(-1). Columns were periodically leached over 5.5 mo to attain 60 mL (1/2 pore volume) of drainage in each leaching. Soluble reactive P was determined and summed over the eight leachings to represent total P source release. Cumulative P release (as a percentage of P applied) was greatest from biological P removal (BPR) and BPR-like biosolids and least from heat-dried materials. Phosphorus release from biosolids depends on biosolids treatment type (digestion) and P chemistry, suggesting that biosolids regulations must account for differences in P lability to accurately gauge environmental risk.     

Biosolids impact soil phosphorus accountability, fractionation, and potential environmental risk

Biosolids land application rates are typically based on crop N requirements but can lead to soil P accumulation. The Littleton/Englewood, Colorado, wastewater treatment facility has supported biosolids beneficial-use on a dryland wheat-fallow agroecosystem site since 1982, with observable soil P concentration increases as biyearly repeated biosolids applications increased from 0, 6.7, 13, 27, to 40 Mg ha(-1). The final study year was 2003, after which P accountability, fractionation, and potential environmental risk were assessed. Between 93 and 128% of biosolids-P added was accounted for when considering conventional tillage soil displacement, grain removal, and soil adsorption. The Fe-P fraction dominated all soil surface P fractions, likely due to an increase in amorphous Fe-oxide because Fe2(SO4)3 was added at the wastewater treatment facility inflow for digester H2S reduction. The Ca-P phase dominated all soil subsurface P fractions due to calcareous soil conditions. A combination of conventional tillage, drought from 1999 to 2003, and repeated and increasing biosolids application rates may have forced soil surface microorganism dormancy, reduction, or mortality; thus, biomass P reduction was evident. Subsurface biomass P was greater than surface biomass, possibly due to protection against environmental and anthropogenic variables or to increased dissolved organic carbon inputs. Even given years of biosolids application, the soil surface had the ability to sorb additional P as determined by shaking the soil in an excessive P solution. Biosolids-application regulations based on the Colorado Phosphorus Index would not impede current site practices. Proper monitoring, management, and addition of other best management practices are needed for continued assurance that P movement off-site does not become a major issue.     

Risk characterization, assessment, and management of organic pollutants in beneficially used residual products

A wide array of organic chemicals occur in biosolids and other residuals recycled to land. The extent of our knowledge about the chemicals and the impact on recycling programs varies from high to very low. Two significant challenges in regulating these materials are to accurately determine the concentrations of the organic compounds in residuals and to appropriately estimate the risk that the chemicals present from land application or public distribution. This paper examines both challenges and offers strategies for assessing the risks related to the occurrence of organic compounds in residuals used as soil amendments. Important attributes that must be understood to appropriately characterize and manage the potential risks for organic chemicals in biosolids include toxicity and dose response, transport potential, chemical structure and environmental stability, analytical capability in the matrix of interest, concentrations and persistence in waste streams, plant uptake, availability from surface application versus incorporation, solubility factors, and environmental fate. This information is complete for only a few chemicals. Questions persist about the far greater number of chemicals for which toxicity and environmental behavior are less well understood. This paper provides a synopsis of analytical issues, risk assessment methodologies, and risk management screening alternatives for organic constituents in biosolids. Examples from experience in Wisconsin are emphasized but can be extrapolated for broader application.     

Phosphorus restrictions for land application of biosolids: current status and future trends

The application of biosolids (sewage sludge) to agricultural soils provides P in excess of crop needs when applied to meet the N needs of most agronomic crops. These overapplications can result in the buildup of P in soils to values well above those needed for optimum crop yields and also may increase risk of P losses to surface and ground waters. Because of concerns regarding the influence of P on water quality in the USA, many state and federal agencies now recommend or require P-based nutrient management plans for animal manures. Similar actions are now under consideration for the land application of biosolids. We reviewed the literature on this subject and conducted a national survey to determine if states had restrictions on P levels in biosolids-amended soils. The literature review indicates that while the current N-based approach to biosolids management does result in increases of soil P, some properties of biosolids may mitigate the environmental risk to water quality associated with land application of P in biosolids. Results of the survey showed that 24 states have regulations or guidelines that can be imposed to restrict land application of biosolids based on P. Many of these states use numerical thresholds for P in biosolids-amended soils that are based on soil test phosphorus (STP) values that are much greater than the values considered to be agronomically beneficial. We suggest there is the need for a comprehensive environmental risk assessment of biosolids P. If risk assessment suggests the need for regulation of biosolids application, we suggest regulations be based on the P Site Index (PSI), which is the method being used by most states for animal manure management.     

The evolving science of chemical risk assessment for land-applied biosolids

Biosolids, effluents, and manures are widely applied to agricultural land and other land with varying degrees of pretreatment or control. Regulations governing land application of biosolids take several broad forms in different countries, including limitations based on rates that do not lead to increases in background chemical concentrations or risk assessment approaches such as those used in the United States. Risk assessment is a process that is inherently limited by currently available information and practices, and consequently, risk-based land application limits must be reevaluated periodically. For complex mixtures such as biosolids, three principal categories of information will be affected by changing practices and scientific advances: (i) chemical constituents present in the material, (ii) the nature of expected exposures, and (iii) toxicity of the chemical constituents. New analytical methods and lower detection limits will affect chemical identification in wastes. Approaches to exposure assessment, such as increasing emphasis on probabilistic analyses, will continue to evolve, and exposure assumptions will change as new studies provide better data on factors such as soil ingestion, plant uptake of chemicals, and bioavailability of chemicals in soil. Similarly, toxicity assessments will be updated as new studies are conducted. The evolving science over the past decade is illustrated by comparing approaches used by the USEPA to assess human health and ecological risks for the Part 503 rule compared with the more recent evaluation of dioxins and related compounds in biosolids. While risks of chemicals in land-applied biosolids and other residuals need to be periodically re-evaluated, such re-evaluations may take forms other than full risk assessments.     

Biosolids effects on phosphorus retention and release in some sandy Florida soils

The soil solid phase components most responsible for P sorption in Florida soils are Fe and Al oxides. Thus, we hypothesized that land application of biosolids would significantly increase a soil's P retention by increasing its content of P-sorbing solids, especially when biosolids with high Fe and Al concentrations are applied to soils that sorb P poorly. Biosolids effects were quantified by a series of single-point isotherms on soils from two field studies sampled for up to 4 yr after initial biosolids application. Biosolids additions had little effect on P retention in a soil with abundant oxalate-extractable Fe and Al and a correspondingly large native P-sorbing capacity. However, biosolids significantly increased P retention in a soil with low oxalate-extractable Fe and Al content and low native P-sorbing capacity. Biosolids effects on P retention lasted 1 to 3 yr after application, depending on biosolids source and rate of application, and generally mimicked persistence of increased extractable Fe and Al concentrations in the poorly P-sorbing soil. Disappearance of added Fe and Al (and, hence, P retention capacity) from the surface horizons over time was relatively rapid, perhaps due to abundant organic acid production associated with biosolids degradation. Phosphorus in biosolids containing (or tailored to contain) abundant Fe and/or Al can be expected to behave as a slowly available P source, and to be less subject to leaching losses than completely soluble P sources.     

Beneficial reuse and sustainability: the fate of organic compounds in land-applied waste

Land application systems, also referred to as beneficial reuse systems, are engineered systems that have defined and permitted application areas based on site and waste characteristics to determine the land area size requirement. These terrestrial systems have orders of magnitude greater microbial capability and residence time to achieve decomposition and assimilation compared with aquatic systems. In this paper we focus on current information and information needs related to terrestrial fate pathways in land treatment systems. Attention is given to conventional organic chemicals as well as new estrogenic and pharmaceutical chemicals of commerce. Specific terrestrial fate pathways addressed include: decomposition, bound residue formation, leaching, runoff, and crop uptake. Molecular decomposition and formation of bound residues provide the basis for the design and regulation of land treatment systems. These mechanisms allow for assimilation of wastes and nondegradation of the environment and accomplish the goal of sustainable land use. Bound residues that are biologically produced are relatively immobile, degrade at rates similar to natural soil materials, and should present a significantly reduced risk to the environment as opposed to parent contaminants. With regard to leaching and runoff pathways, no comprehensive summary or mathematical model of organic chemical migration from land treatment systems has been developed. For the crop uptake pathway, a critical need exists to develop information for nonagricultural chemicals and to address full-scale performance and monitoring at more land application sites. The limited technology choices for treatment of biosolids, liquids, and other wastes implies that acceptance of some risks and occurrence of some benefits will continue to characterize land application practices that contribute directly to the goal of beneficial reuse and sustainability.     

Sources of pathogenic microorganisms and their fate during land application of wastes

The hazards associated with pathogens in land-applied animal and human wastes have long been recognized. Management of these risks requires an understanding of sources, concentrations, and removal by processes that may be used to treat the wastes; survival in the environment; and exposure to sensitive populations. The major sources are animal feeding operations, municipal wastewater treatment plant effluents, biosolids, and on-site treatment systems. More than 150 known enteric pathogens may be present in the untreated wastes, and one new enteric pathogen has been discovered every year over the past decade. There has been increasing demand that risks associated with the land treatment and application be better defined. For risks to be quantified, more data are needed on the concentrations of pathogens in wastes, the effectiveness of treatment processes, standardization of detection methodology, and better quantification of exposure.     

Copper availability in seven Israeli soils incubated with and without biosolids

Land application is becoming a preferred option for disposal of sewage sludge (biosolids) from wastewater treatment plants. However, it creates potential risks due to the heavy metal contents of these materials, with copper (Cu) being of chief concern. The long-term fate of biosolid metals applied to agricultural soils is not well understood, particularly in the soils of the Middle East. This investigation was conducted to determine whether the availability of Cu changes with time in biosolid-amended and nonamended soils from Israel. Seven soils, typifying the span of properties and formation environments encountered in Israel, were incubated with and without biosolids for 7 yr, and changes in organic carbon (OC) content and labile Cu concentration were determined. Isotopic exchange techniques, using 64Cu, and ion activity measurements, using a Cu2+ ion selective electrode, revealed that the available Cu concentration remained relatively low and stable over the 7-yr incubation. This was despite substantial reductions in OC. This study shows that, with regard to Cu, application of such biosolids to these soils at rates of up to 250 Mg ha(-1) does not pose a threat to the environment in the short to medium term.     

Phosphorus forms in biosolids-amended soils and losses in runoff: effects of wastewater treatment process

Continuous addition of municipal biosolids to soils based on plant nitrogen (N) requirements can cause buildup of soil phosphorus (P) in excess of crop requirements; runoff from these soils can potentially contribute to nonpoint P pollution of surface waters. However, because biosolids are often produced using lime and/or metal salts, the potential for biosolids P to cause runoff P losses can vary with wastewater treatment plant (WWTP) process. This study was conducted to determine the effect of wastewater treatment process on the forms and amounts of P in biosolids, biosolids-amended soils, and in runoff from biosolids-amended soils. We amended two soil types with eight biosolids and a poultry litter (PL) at equal rates of total P (200 kg ha(-1); unamended soils were used as controls. All biosolids and amended soils were analyzed for various types of extractable P, inorganic P fractions, and the degree of P saturation (acid ammonium oxalate method). Amended soils were placed under a simulated rainfall and all runoff was collected and analyzed for dissolved reactive phosphorus (DRP), iron-oxide-coated filter paper strip-extractable phosphorus (FeO-P), and total phosphorus (EPA3050 P). Results showed that biosolids produced with a biological nutrient removal (BNR) process caused the highest increases in extractable soil P and runoff DRP. Alternatively, biosolids produced with iron only consistently had the lowest extractable P and caused the lowest increases in extractable soil P and runoff DRP when added to soils. Differences in soil and biosolids extractable P levels as well as P runoff losses were related to the inorganic P forms of the biosolids.     

Characterization of phosphorus species in biosolids and manures using XANES spectroscopy

Identification of the chemical P species in biosolids or manures will improve our understanding of the long-term potential for P loss when these materials are land applied. The objectives of this study were to determine the P species in dairy manures, poultry litters, and biosolids using X-ray absorption near-edge structure (XANES) spectroscopy and to determine if chemical fractionation techniques can provide useful information when interpreted based on the results of more definitive P speciation studies. Our XANES fitting results indicated that the predominant forms of P in organic P sources included hydroxylapatite, PO(4) sorbed to Al hydroxides, and phytic acid in lime-stabilized biosolids and manures; hydroxylapatite, PO(4) sorbed on ferrihydrite, and phytic acid in lime- and Fe-treated biosolids; and PO(4) sorbed on ferrihydrite, hydroxylapatite, beta-tricalcium phosphate (beta-TCP), and often PO(4) sorbed to Al hydroxides in Fe-treated and digested biosolids. Strong relationships existed between the proportions of XANES PO(4) sorbed to Al hydroxides and NH(4)Cl- + NH(4)F-extractable P, XANES PO(4) sorbed to ferrihydrite + phytic acid and NaOH-extractable P, and XANES hydroxylapatite + beta-TCP and dithionite-citrate-bicarbonate (DCB)- + H(2)SO(4)-extractable P (r(2) = 0.67 [P = 0.01], 0.78 [P = 0.01], and 0.89 [P = 0.001], respectively). Our XANES fitting results can be used to make predictions about long-term solubility of P when biosolids and manures are land applied. Fractionation techniques indicate that there are differences in the forms of P in these materials but should be interpreted based on P speciation data obtained using more advanced analytical tools.     

Leaching of pharmaceuticals and personal care products in turfgrass soils during recycled water irrigation

An important beneficial reuse of treated wastewater (recycled water) in arid and semiarid regions is landscape irrigation. However, the environmental fate, especially groundwater contamination potential, of trace contaminants such as pharmaceuticals and personal care products (PPCPs) is a significant concern that can hinder the acceptance and adoption of such reuses. In this study, we irrigated mature turfgrass plots with nonspiked tertiary treated wastewater for over 6 mo at 100 or 130% of the reference evapotranspiration rate (ETo) and collected leachate water at the 90-cm depth on a weekly basis. In the recycled water, all 14 target PPCPs were consistently found, and the mean levels of atenolol, gemfibrozil, meprobamate, carbamazepine, and sulfamethoxazole were above 100 ng L. However, only five compounds were detected in the leachate at trace levels. Trimethoprim and primidone were frequently found, whereas the detection of sulfamethoxazole, meprobamate and carbamazepine was less frequent (<50%). When detected, the overall mean concentration in the leachate was 10.2 ng L for trimethoprim, 7.1 ng L for primidone, and 2.9 to 12.4 ng L for carbamazepine, sulfamethoxazole, and meprobamate. The majority of the target PPCPs were completely removed. Given that the irrigation rates were higher than normal, this study clearly demonstrated the efficacy of turfgrass systems in attenuating PPCPs during recycled water irrigation. However, it is also apparent that some PPCPs are more susceptible to leaching than others, and these PPCPs thus merit further research attention.     

高级氧化法去除水中药物和个人护理用品的研究进展

药品和个人护理用品(PPCPs)由于其对环境及人体具有潜在影响,受到国内外越来越多的关注。高级氧化技术(AOPs)对于处理PPCPs极具发展前景。本文概括了药品和个人护理用品(PPCPs)的概念和种类,并对几种高级氧化技术处理PPCPs的基本原理和处理效果做了较为详细的阐述并提出进一步可能的研究方向。     

Runoff phosphorus losses from surface-applied biosolids

Runoff losses of dissolved and particulate phosphorus (P) may occur when rainfall interacts with manures and biosolids spread on the soil surface. This study compared P levels in runoff losses from soils amended with several P sources, including 10 different biosolids and dairy manure (untreated and treated with Fe or Al salts). Simulated rainfall (71 mm h(-1)) was applied until 30 min of runoff was collected from soil boxes (100 x 20 x 5 cm) to which the P sources were surfaced applied. Materials were applied to achieve a common plant available nitrogen (PAN) rate of 134 kg PAN ha(-1), resulting in total P loading rates from 122 (dairy manure) to 555 (Syracuse N-Viro biosolids) kg P ha(-1). Two biosolids produced via biological phosphorus removal (BPR) wastewater treatment resulted in the highest total dissolved phosphorus (13-21.5 mg TDP L(-1)) and total phosphorus (18-27.5 mg TP L(-1)) concentrations in runoff, followed by untreated dairy manure that had statistically (p = 0.05) higher TDP (8.5 mg L(-1)) and TP (10.9 mg L(-1)) than seven of the eight other biosolids. The TDP and TP in runoff from six biosolids did not differ significantly from unamended control (0.03 mg TDP L(-1); 0.95 mg TP L(-1)). Highest runoff TDP was associated with P sources low in Al and Fe. Amending dairy manure with Al and Fe salts at 1:1 metal-to-P molar ratio reduced runoff TP to control levels. Runoff TDP and TP were not positively correlated to TP application rate unless modified by a weighting factor reflecting the relative solubility of the P source. This suggests site assessment indices should account for the differential solubility of the applied P source to accurately predict the risk of P loss from the wide variety of biosolids materials routinely land applied.     

Odorants and malodors associated with land application of biosolids stabilized with lime and coal fly ash

Malodor emissions limit public acceptance of using municipal biosolids as natural organic resources in agricultural production. We aimed to identify major odorants and to evaluate odor concentrations associated with land application of anaerobically digested sewage sludges (Class B) and their alkaline (lime and coal fly ash)-stabilized products (Class A). These two types of biosolids were applied at 12.6 tonnes ha(-1) (dry weight) to microplots of very fine clayey Vertisol in the Jezreel Valley, northern Israel. The volatile organic compounds (VOCs) emitted from the biosolids before and during alkaline stabilization and after incorporation into the soil were analyzed by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry. Odor concentrations at the plots were evaluated on site with a Nasal Ranger field olfactometer that sniffed over a defined land surface area through a static chamber. The odors emitted by anaerobically digested sewage sludges from three activated sludge water treatment plants had one characteristic chemical fingerprint. Alkaline stabilization emitted substantial odors associated with high concentrations of ammonia and release of nitrogen-containing VOCs and did not effectively reduce the potential odor annoyance. Odorous VOCs could be generated within the soil after biosolids incorporation, presumably because of anaerobic conditions within soil-biosolids aggregates. We propose that dimethyl disulfide and dimethyl trisulfide, which seem to be most related to the odor concentrations of biosolids-treated soil, be used as potential chemical markers for the odor annoyance associated with incorporation of anaerobically digested sewage sludges.     

Occurrence of Primidone,Carbamazepine, Caffeine,and Precursors for N‐Nitrosodimethylamine in Drinking Water Sources Impacted by Wastewater1

Abstract: Wastewater impact on drinking water sources was assessed using several approaches, including analysis of three pharmaceuticals and personal care products (PPCPs) – primidone, carbamazepine, and caffeine – as indicators, and determination of precursor concentrations for the disinfection byproduct N‐nitrosodimethylamine (NDMA) using formation potential (FP) tests. Samples were collected in 2006 and 2007 in rivers impacted by wastewater treatment plant (WWTP) discharges, at drinking water treatment plant (DWTP) intakes upstream or downstream from these discharges, and from two WWTP effluents in two watersheds. The levels [10th percentile ? maximum (median)] of primidone, carbamazepine, caffeine, and NDMAFP were 2‐95 (7) ng/l, 2‐207 (18) ng/l, 7‐687 (78) ng/l, and 12‐321 (35) ng/l, respectively. The highest concentrations of primidone, carbamazepine, and NDMA precursors were from one of the WWTP effluents, whereas the highest concentration of caffeine was detected in a river heavily impacted by treated wastewater discharges. The lowest concentrations of the three PPCPs were from a DWTP influent upstream of a metropolitan urban area with minimum wastewater impact. Temporal variations in PPCP and NDMAFP concentrations and streamflows in two selected watersheds were also observed. Furthermore, correlation analysis between caffeine or carbamazepine and primidone was evaluated. The results show that measurement of the two pharmaceuticals and NDMAFP tests can be used to evaluate wastewater impact in different watersheds, whereas caffeine results were more variable.