Sequential UV-biological degradation of chlorophenols

The sequential UV-biological degradation of a mixture of 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) was first tested with each pollutant supplied at an initial concentration of 50 mg l(-1). Under these conditions, the chlorophenols were photodegraded in the following order of removal rate: PCP>TCP>DCP>CP with only CP and DCP remaining after 40 h of irradiation. The remaining CP (41 mg l(-1)) and DCP (13 mg l(-1)) were then completely removed by biological treatment with an activated sludge mixed culture. Biodegradation did not occur in similar tests conducted with a non-irradiated mixture due to the high microbial toxicity of the solution. UV treatment lead to a significant reduction of the phytotoxicity to Lipedium sativum but no further reduction of phytotoxicity was observed after biological treatment. Evidence was found that the pollutants were partially photodegraded into toxic and non-biodegradable products. When the pollutants were tested individually (initial concentration of 50 mg l(-1)), PCP, TCP, DCP, 4-CP were photodegraded according to first order kinetic model (r2>99) with half-lives of 2.2, 3.3, 5.7, and 54 h, respectively. The photoproducts were subsequently biodegraded. This study illustrates the potential of UV as pre-treatment for biological treatment in order to remove toxicity and enhance the biodegradability of organic contaminants. However, it also shows that UV treatment must be carefully optimized to avoid the formation of toxic and/or recalcitrant photoproducts and results from studies conducted on single contaminants cannot be extrapolated to mixtures.     

Systematic review and meta-analysis of glyphosate exposure and risk of lymphohematopoietic cancers

This systematic review and meta-analysis rigorously examines the relationship between glyphosate exposure and risk of lymphohematopoietic cancer (LHC) including NHL, Hodgkin lymphoma (HL), multiple myeloma (MM), and leukemia. Meta-relative risks (meta-RRs) were positive and marginally statistically significant for the association between any versus no use of glyphosate and risk of NHL (meta-RR = 1.3, 95% confidence interval (CI) = 1.0–1.6, based on six studies) and MM (meta-RR = 1.4, 95% CI = 1.0–1.9; four studies). Associations were statistically null for HL (meta-RR = 1.1, 95% CI = 0.7–1.6; two studies), leukemia (meta-RR = 1.0, 95% CI = 0.6–1.5; three studies), and NHL subtypes except B-cell lymphoma (two studies each). Bias and confounding may account for observed associations. Meta-analysis is constrained by few studies and a crude exposure metric, while the overall body of literature is methodologically limited and findings are not strong or consistent. Thus, a causal relationship has not been established between glyphosate exposure and risk of any type of LHC.     

Short-term effects of gaseous pollutants on cause-specific mortality in Wuhan, China

In Asia, limited studies have been published on the association between daily mortality and gaseous pollutants of nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2). Our previous studies in Wuhan, China, demonstrated long-term air pollution effects. However, no study has been conducted to determine mortality effects of air pollution in this region. This study was to determine the acute mortality effects of the gaseous pollutants in Wuhan, a city with 7.5 million permanent residents during the period from 2000 to 2004. There are approximately 4.5 million residents in Wuhan who live in the city's core area of 201 km2, where air pollution levels are highest, and pollution ranges are wider than the majority of the cities in the published literature. We used the generalized additive model to analyze pollution, mortality, and covariate data. We found consistent NO2 effects on mortality with the strongest effects on the same day. Every 10-microg/m3 increase in NO2 daily concentration on the same day was associated with an increase in nonaccidental (1.43%; 95% confidence interval [CI]: 0.87-1.99%), cardiovascular (1.65%; 95% CI: 0.87-2.45%), stroke (1.49%; 95% CI: 0.56-2.43%), cardiac (1.77%; 95% CI: 0.44-3.12%), respiratory (2.23%; 95% CI: 0.52-3.96%), and cardiopulmonary mortality (1.60%; 95% CI: 0.85-2.35%). These effects were stronger among the elderly than among the young. Formal examination of exposure-response curves suggests no-threshold linear relationships between daily mortality and NO2, where the NO2 concentrations ranged from 19.2 to 127.4 microg/m3. SO2 and O3 were not associated with daily mortality. The exposure-response relationships demonstrated heterogeneity, with some curves showing nonlinear relationships for SO2 and O3. We conclude that there is consistent evidence of acute effects of NO2 on mortality and suggest that a no-threshold linear relationship exists between NO2 and mortality.     

Dechlorination and destruction of 2,4,6-trichlorophenol and pentachlorophenol using hydrogen peroxide as the oxidant catalyzed by molybdate ions under basic condition

The dechlorination and destruction of 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) under basic condition using hydrogen peroxide as the oxidant catalyzed by molybdate ions have been studied. Under ambient conditions of temperature and pressure, more than 95% of millimolar solutions of TCP and PCP can be converted to CO2 and CO, chlorinated and nonchlorinated carboxylic acid in 40 min. Up to 2.4 chloride ions per TCP and 3.5 chloride ions per PCP were released. TOC measurements indicated that 18% and 11% of the carbon was mineralized for TCP and PCP respectively after an hour of reaction. The results of ESR measurements suggested that the reaction possibly proceeded via the pathway with singlet oxygen.     

Serum profiles of PCDDs and PCDFs, in individuals near the Escambia Wood Treating Company Superfund site in Pensacola, FL

The Escambia Wood Treating Company (ETC) Superfund site, Pensacola, FL, is contaminated with polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), benzo(a)pyrene, lead and arsenic from pentachlorophenol (PCP), creosote, and other compounds used to treat utility poles and foundation pilings. Although ETC's operations ceased in 1982, soils in the areas surrounding the facility continue to exhibit elevated levels of contaminants attributable to ETC operations. In July 2000, individuals who may have been affected by contamination from the ETC site, including current and former residents and former workers and their household members were invited to participate in a study, which included a health and exposure history and routine blood analysis. We also conducted a toxicological health evaluation of a subset of these eligible workers/residents by analyzing serum levels of 17 PCDD/F congeners. Members of the ETC cohort exhibited elevated serum PCDD/F relative to the general population, and congener profiles in members of the cohort reflected patterns commonly observed in persons exposed to PCP. Hypertension prevalence in the cohort was found to correlate with PCDD/F levels, although no other significant relationships were identified with monitored health indices.     

Distance-weighted traffic density in proximity to a home is a risk factor for leukemia and other childhood cancers

Occupational exposure to elevated concentrations of benzene is a known cause of leukemia in adults. Concentrations of benzene from motor vehicle exhaust could be elevated along highly trafficked streets. Several studies have reported significant associations between proximity to highly trafficked streets and the occurrence of childhood cancers and childhood leukemia. These associations may be due to chronic exposure to benzene or other carcinogenic components of vehicle exhaust from these nearby streets or to some other factor (e.g., noise, increased light exposure, or some unaccounted--for socioeconomic variable). We used data for homes studied in an earlier childhood cancer study conducted in Denver, CO, in the 1980s. No air pollution measurements were made in the original study. We identified the highest trafficked street near each study home and obtained the traffic density in 1979 and 1990. Traffic density was weighted for the distance from the street to the home using 3 different widths of Gaussian curves to approximate the decay of the emissions into the surrounding neighborhoods. The associations between the 750-ft-wide distance-weighted traffic density metrics and all childhood cancers and childhood leukemia are strongest in the highest traffic density category (> or = 20,000 vehicles per day [VPD]). The odds ratio is 5.90 (95% confidence interval [CI] 1.69-20.56) for all cancers and 8.28 (95% CI 2.09-32.80) for leukemia. The results are suggestive of an association between proximal high traffic streets with traffic counts > or = 20,000 VPD and childhood cancer, including leukemia.     

Role of plant activity and contaminant speciation in aquatic plant assimilation of 2,4,5-trichlorophenol

Aquatic plants uptake, transform and sequester organic contaminants and are used as a bioremediation strategy for the removal of pollutants from wastewaters. A better understanding of factors affecting rate of uptake of contaminants by aquatic plants is needed to improve engineered systems for removal of pollutants from wastewaters. This work focused on delineating sorption to plant surfaces and understanding effects of plant metabolic activity, inhibition, and media pH on the uptake of the ionizable contaminant 2,4,5-trichlorophenol (TCP) by aquatic plant Lemna minor. During L. minor exposure to TCP (0.5-13.9 mg l(-1)), a range of plant metabolic activities was measured using oxygen production rate (0-18.4 micromol h(-1)). A positive correlation was shown between contaminant uptake rate and plant activity. Contaminant uptake was examined at a range of media pH values (6-9) and uptake rates were linearly correlated to fraction of contaminant in protonated form. These results demonstrated a link between plant activity and uptake of contaminant by plants and stress the importance of incorporating plant metabolic activity and contaminant speciation in development of natural and engineered phytoremediation systems. This research also indicates that aquatic plants can actively accumulate trace-organic contaminants and may ultimately serve as a sink for these materials in the natural environment.     

Gas chromatographic methods for monitoring of wastewater chlorophenol degradation in anaerobic reactors

Wastewater samples from an anaerobic reactor were extracted with hexane and derivatized with diazomethane (method 1) and with acetic anidride (method 2). Gas chromatography with electron-capture detection (ECD) was employed for separating the parent compound and intermediates trichlorophenols (TCP) and dichlorophenols (DCP) which originated from the penta chlorophenol (PCP) degradation process. The relations between concentrations of PCP, TCP and DCP areas were linear in the range of concentrations of 0.2 to 8 mg/L and 0.025 mg/L to 5 mg/L for methods 1 and 2, respectively. The repeatability of the extraction methods was satisfactory, with variation coefficients lower than 11%. For method 1, at the fortification level of 0.2 mg/L, recovery of PCP, TCP, and DCP was 112%, 74% and 45%, respectively. For method 2, the corresponding recovery values at the fortification level of 0.1 mg/L were 91%, 93% and 103%, respectively. Storage of the frozen samples did not alter their PCP determination properties. The chromatographic methods adapted for chlorophenol determination in wastewater were suitable with relatively simple manipulation techniques. The obtained results were reproducible and allowed identification of intermediates formed during the PCP degradation process.     

Gas chromatographic methods for monitoring of wastewater chlorophenol degradation in anaerobic reactors

Wastewater samples from an anaerobic reactor were extracted with hexane and derivatized with diazomethane (method 1) and with acetic anidride (method 2). Gas chromatography with electron-capture detection (ECD) was employed for separating the parent compound and intermediates trichlorophenols (TCP) and dichlorophenols (DCP) which originated from the penta chlorophenol (PCP) degradation process. The relations between concentrations of PCP, TCP and DCP areas were linear in the range of concentrations of 0.2 to 8 mg/L and 0.025 mg/L to 5 mg/L for methods 1 and 2, respectively. The repeatability of the extraction methods was satisfactory, with variation coefficients lower than 11%. For method 1, at the fortification level of 0.2 mg/L, recovery of PCP, TCP, and DCP was 112%, 74% and 45%, respectively. For method 2, the corresponding recovery values at the fortification level of 0.1 mg/L were 91%, 93% and 103%, respectively. Storage of the frozen samples did not alter their PCP determination properties. The chromatographic methods adapted for chlorophenol determination in wastewater were suitable with relatively simple manipulation techniques. The obtained results were reproducible and allowed identification of intermediates formed during the PCP degradation process.     

Mobility of polychlorinated aromatic compounds in soils contaminated with wood-preserving oil

Greater understanding of the mobility of polychlorinated aromatic compounds in soils is needed to investigate contamination and design suitable remediation strategies for sites contaminated with wood-preserving oil. The objectives of this study were (1) to develop a suitable aqueous batch extraction method for soil containing wood-preservative residues; (2) to determine partition coefficients for the primary contaminants [pentachlorophenol (PCP), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFS)] in oil, soil, and aqueous phases; and (3) to evaluate the potential soil migration of the primary contaminants. In a three-phase oil-soil-water mixture, PCP, PCDDs, and PCDFs were partitioned to the greatest extent in the oil phase. These results suggest that the migration of contaminants can occur in a saturated subsurface soil zone containing an oil phase at a wood-preserving site. In the absence of a free oil phase, PCDDs and PCDFs were highly partitioned onto soil and were considered non-leachable in the aqueous phase. However, PCP was considered highly leachable from contaminated soil containing only an aqueous liquid phase. Results from this study indicate that removal of any free oil phase present in subsurface soil should have highest priority during the cleanup of contaminated wood-preserving sites.     

Mobility of Polychlorinated Aromatic Compounds in Soils Contaminated With Wood-preserving Oil

Greater understanding of the mobility of polychlorinated aromatic compounds in soils is needed to investigate contamination and design suitable remediation strategies for sites contaminated with wood-preserving oil. The objectives of this study were (1) to develop a suitable aqueous batch extraction method for soil containing wood-preservative residues; (2) to determine partition coefficients for the primary contaminants [pentachlorophenol (PCP), polychlorinated dibenzo-p-dloxins (PCDDs), and polychlorinated dibenzofurans (PCDFS)] in oil, soil, and aqueous phases; and (3) to evaluate the potential soil migration of the primary contaminants. In a three-phase oil-soil-water mixture, PCP, PCDDs, and PCDFs were partitioned to the greatest extent in the oil phase. These results suggest that the migration of contaminants can occur in a saturated subsurface soil zone containing an oil phase at a wood-preserving site. In the absence of a free oil phase, PCDDs and PCDFs were highly partitioned onto soil and were considered non-leachable in the aqueous phase. However, PCP was considered highly teachable from contaminated soil containing only an aqueous liquid phase. Results from this study Indicate that removal of any free oil phase present in subsurface soil should have highest priority during the cleanup of contaminated wood-preserving sites.     

高效代谢解偶联剂的筛选及对SBR系统综合运行效能的影响

活性污泥法是最常用的污水处理技术,但它同时会产生大量的剩余污泥,需要进行额外的处理和处置.活性污泥的解偶联代谢能有效地减少剩余污泥的产量.比较了5种代谢解偶联剂,即2,4-二硝基苯酚(DNP)、邻氨基苯酚(AP)、2,4,6-三氯苯酚(TCP)、3,3',4,5-四氯水杨酰苯胺(TCS)、丙二酸的污泥减量效果和对COD去除能力的影响.结果表明,当它们在各自的最佳质量浓度20、1 5、4、1.2、15 mg/L时,污泥的表观增长系数分别降低了62.39%、63.75%、59.40%、34.58%和53.75%,而COD去除率仅有轻微下降.重点研究了15 mg/L的丙二酸和4 mg/L的TCP对SBR系统运行效能和污泥沉降性能的影响.发现在长期运行过程中,两者都能有效降低系统的污泥产量,而对COD去除率的影响较低,但使用丙二酸6 d后极大地影响了污泥的沉降性能,而TCP对污泥的沉降性能影响很小.     

Short-Term Effects of Gaseous Pollutants on Cause-Specific Mortality in Wuhan,China

Abstract

In Asia, limited studies have been published on the association between daily mortality and gaseous pollutants of nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂). Our previous studies in Wuhan, China, demonstrated long-term air pollution effects. However, no study has been conducted to determine mortality effects of air pollution in this region. This study was to determine the acute mortality effects of the gaseous pollutants in Wuhan, a city with 7.5 million permanent residents during the period from 2000 to 2004. There are approximately 4.5 million residents in Wuhan who live in the city’s core area of 201 km², where air pollution levels are highest, and pollution ranges are wider than the majority of the cities in the published literature. We used the generalized additive model to analyze pollution, mortality, and covariate data. We found consistent NO₂effects on mortality with the strongest effects on the same day. Every 10-μg/m³increase in NO₂daily concentration on the same day was associated with an increase in nonaccidental (1.43%; 95% confidence interval [CI]: 0.87–1.99%), cardiovascular (1.65%; 95% CI: 0.87–2.45%), stroke (1.49%; 95% CI: 0.56–2.43%), cardiac (1.77%; 95% CI: 0.44–3.12%), respiratory (2.23%; 95% CI: 0.52–3.96%), and cardiopulmonary mortality (1.60%; 95% CI: 0.85– 2.35%). These effects were stronger among the elderly than among the young. Formal examination of exposure-response curves suggests no-threshold linear relationships between daily mortality and NO₂, where the NO₂concentrations ranged from 19.2 to 127.4 μg/m³. SO₂and O₃were not associated with daily mortality. The exposure-response relationships demonstrated heterogeneity, with some curves showing nonlinear relationships for SO₂and O₃. We conclude that there is consistent evidence of acute effects of NO₂on mortality and suggest that a no-threshold linear relationship exists between NO₂and mortality.     

Impact of four pesticides on the growth and metabolic activities of two photosynthetic algae

The acute toxicity was determined for soil algae Chlorella kesslerei and Anabaena inaequalis, exposed to pesticides lindane, pentachlorophenol (PCP), isoproturon (IPU), and methyl parathion (MP). Toxicity markers included growth inhibition, chlorophyll biosynthesis, and total carbohydrate content, as a function of dose and time. Concentration response functions (EC50) were estimated by probit data transformation and weighted linear regression analyses. Lindane's toxicity to Chlorella increased sharply with time (EC50 = 7490, 10.3, 0.09 mg L(-1); 24, 48, 72 h), but remained nearly constant through 72 h with Anabaena (8.7-6.7 mg L(-1); 24-72 h). PCP at low concentrations stimulated algal growth and chlorophyll a production, an effect reversed at higher doses. Anabaena was less tolerant of PCP and MP than was Chlorella. The 96-h static EC50 values for Chlorella were: 0.003, 34, 0.05, and 291 mg L(-1) for lindane, PCP, isoproturon, and MP, respectively; for Anabaena, these were 4.2, 0.13, 0.21, and 19 mg L(-1). Carbohydrate production responses were similar to those of cell density (growth) and chlorophyll biosynthesis, with MP having the lowest adverse impact. The overall relative toxicity among the four tested pesticides was: for Chlorella, lindane > IPU > PCP > MP; and for Anabaena, PCP > IPU > lindane > MP. The results confirm that toxicants such as these pesticides may affect individual (though related) species to significantly different degrees.     

Evaluation of the mortality experience of workers exposed to the chlorinated dioxins

Mortality patterns were analyzed for the time period 1940 through 1979 of 2,189 men with potential occupational exposure to chlorinated dibenzo-p-dioxins. Special attention was directed toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and deaths due to soft-tissue sarcoma, non-Hodgkins lymphoma, Hodgkins disease, liver cancer, stomach cancer, and nasal or nasopharyngeal cancer. With United States white males as the comparison population for this employee cohort, the stadardized mortality ratio for all causes of death was 91 and for total malignant neoplasms, 96. Among the malignancy categories of particular interest, none demonstrated a significant deviation from expected. Nor were any significant trends noted for any specific cause of death category when analyzed by estimated cumulative exposure.     

Release of pentachlorophenol from black carbon-inclusive sediments under different environmental conditions

To investigate the feasibility of using black carbon (BC) in the control of hydrophobic organic contaminants (HOCs) in sediment, we added BCs from various sources (rice straw charcoal (RC), fly ash (FC) and soot (SC)) to sediment to create different BC-inclusive sediments and studied the release of pentachlorophenol (PCP) in the sediments under different condition. Different pH values had no obvious effect on the release of PCP in BC-inclusive sediment, but solid/liquid ratio, temperature, salinity and dissolved organic matter (DOM) content had significant influences on the release of PCP in all sediments except the RC-inclusive sediment. Adding 2% RC to sediment resulted in a 90% decrease in PCP release, which was a greater decrease than observed with FC- and SC-inclusive sediments. Therefore, from the standpoint of HOC release, the application of RC is feasible for organic pollution control in the water environment.     

The microbiota of an unpolluted calcareous soil faces up chlorophenols: Evidences of resistant strains with potential for bioremediation

To highlight the effects of a variety of chlorophenols (CP) in relation to the response of an indigenous bacterial community, an agricultural Mediterranean calcareous soil has been studied in microcosms incubated under controlled laboratory conditions. Soil samples were artificially polluted with 2-monochlorophenol (MCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP), at concentrations ranging from 0.1 up to 5000 mg kg⁻¹. Both activity and composition of the microbial community were assessed during several weeks, respectively, by respirometric methods and PCR-DGGE analysis of extracted DNA and RNA. Significant decreases in soil respirometric values and changes in the bacterial community composition were observed at concentrations above 1000 mg kg⁻¹ MCP and TCP, and above 100 mg kg⁻¹ PCP. However, the persistence of several active bacterial populations in soil microcosms contaminated with high concentration of CP, as indicated by DGGE fingerprints, suggested the capacity of these native bacteria to survive in the presence of the pollutants, even without a previous adaptation or contact with them.The isolation of potential CP degraders was attempted by culture plating from microcosms incubated with high CP concentrations. Twenty-three different isolates were screened for their resistance to TCP and PCP. The most resistant isolates were identified as Kocuria palustris, Lysobacter gummosus, Bacillus sp. and Pseudomonas putida, according to 16S rRNA gene homology. In addition, these four isolates also showed the capacity to reduce the concentration of TCP and PCP from 15% to 30% after 5 d of incubation in laboratory assays (initial pollutant concentration of 50 mg L⁻¹). Isolate ITP29, which could be a novel species of Bacillus, has been revealed as the first known member in this bacterial group with potential for CP bioremediation applications, usually wide-spread in the soil natural communities, which has not been reported to date as a CP degrader.     

Meta-analysis of time-series studies of air pollution and mortality: effects of gases and particles and the influence of cause of death,age, and season

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 microg/m3 particulate matter (PM) of median diameter < or = 10 microm (PM10); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO2; 1.6% (1.1-2.0%) per 31.2 ppb O3; and 0.9% (0.7-1.2%) per 9.4 ppb SO2 (daily maximum concentration for O3, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM10 and SO2. Larger effect sizes were observed for respiratory mortality for all pollutants except O3. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Porous organoclay composite for the sorption of polycyclic aromatic hydrocarbons and pentachlorophenol from groundwater

Complex mixtures of hazardous chemicals such as polycyclic aromatic hydrocarbons (PAHs) in contaminated soil and groundwater can have severe and long-lasting effects on health. The evidence that these contaminants can cause adverse health effects in animals and humans is rapidly expanding. The frequent and wide-spread occurrence of PAHs in groundwater makes appropriate intervention strategies for their remediation highly desirable. The core objective of this research was to assess the ability of a clay-based composite to sorb and remove toxic contaminants from groundwater at a wood-preserving chemical waste site. Treatment efficiencies were evaluated using either effluent from an oil-water separator (OWS) or a bioreactor (B2). The effluent water from these units was passed through fixed bed columns containing either an organoclay composite or granular activated carbon. The sorbent columns were placed in-line using existing sampling ports at the effluent of the OWS or B2. Individual one-liter samples of treated and untreated effluent were collected in Kimax bottles over the course of 78 h (total of 50 samples). Subsequently each sample was extracted by solid phase extraction methodology, and pentachlorophenol (PCP) and PAH concentrations were quantitated via GC/MS. Columns containing porous organoclay composite, i.e. sand-immobilized cetylpyridinium-exchanged low-pH montmorillonite clay (CP/LPHM), were shown to reduce the contaminant load from the OWS effluent stream by 97%. The concentrations of benzo[a]pyrene (BaP) and PCP were considerably reduced (i.e. >99%). An effluent stream from the bioreactor was also filtered through columns packed with composite or an equivalent amount of GAC. Although the composite reduced the majority of contaminants (including BaP and PCP), it was less effective in diminishing the levels of lower ring versus higher ring PAHs. Conversely, GAC was more effective in removing the lower ring PAHs, except for naphthalene and PCP. The effectiveness of sorption of PCP from the OWS effluent by the composite was confirmed using a PCP-sensitive adult hydra bioassay previously described in our laboratory. The findings of this initial study have delineated differences between CP/LPHM and GAC for groundwater remediation, and suggest that GAC (instead of sand) as the solid support for organoclay may be more effective for the treatment of contaminated groundwater under field conditions than GAC or CP/LPHM alone. Further work is ongoing to confirm this conclusion.     

Is daily mortality associated specifically with fine particles? Data reconstruction and replication of analyses

In 1996, Schwartz, Dockery, and Neas reported that daily mortality was more strongly associated with concentrations of PM2.5 than with concentrations of larger particles (coarse mass [CM]) in six U.S. cities ("original paper"/"original analyses"). Because of the public policy implications of the findings and the uniqueness of the concentration data, we undertook a reanalysis of these results. This paper presents results of the reconstruction of these data and replication of the original analyses using the reconstructed data. The original investigators provided particulate air pollution data for this paper. Daily weather and daily counts of total and cause-specific deaths were reconstructed from original public records. The reconstructed particulate air pollution and weather data were consistent with the summaries presented in the original paper. Daily counts of deaths in the reconstructed data set were lower than in the original paper because of restrictions on residence and place of death. The reconstruction process identified an administrative change in county codes that led to higher numbers of deaths in St. Louis. Despite these differences in daily counts of deaths, the estimated effects of particulate air pollution from the reconstructed dataset, using analytic methods as described in the original paper, produced combined effect estimates essentially equivalent to the originally published results. For example, the estimated association of a 10 micrograms/m3 increase in 2-day mean particulate air pollution on total mortality was 1.3% (95% confidence interval [CI] 0.9-1.7%, t = 6.53) for PM2.5 based on the reconstructed dataset, compared to the originally reported association of 1.5% (95% CI 1.1-1.9%, t = 7.41). For coarse particles, the estimated association from the reconstructed dataset was 0.4% (95% CI -0.2-0.9%, t = 1.43) compared to the originally reported association of 0.4% (95% CI -0.1-1.0%, t = 1.48). These results from the reconstructed data suggest that the original results reported by Schwartz, Dockery, and Neas were essentially replicated.