Evaluation, selection and initial performance of a large scale centralised biosolids facility at Oxley Creek Water Reclamation Plant, Brisbane.

Recent upgrades to Brisbane City Council's Water Reclamation Plants (WRP) for improved nutrient removal has led to a significant increase in sludge production, and loss in potential anaerobic degradability. This increase in sludge production brought forth an economic driver for an improved, integrated biosolids handling strategy. The solution adopted by Brisbane Water, was a centralised thermal hydrolysis facility at Oxley Creek WRP to process the waste activated sludges generated at a total of five WRPs in the region. The thermal hydrolysis process uses high temperature and pressure to make non-degradable material more readily digestible by anaerobic bacteria and hence achieve greater efficiency in the overall anaerobic digestion process. Dewaterability is also improved, as the thermal hydrolysis process releases some of the bound water from the waste activated sludge. The viability of this solution is linked primarily to the reduction in mass and volume of biosolids which leads to lower transportation and disposal costs. After four months of operation, the Oxley Creek thermal hydrolysis plant has resulted in a 70% reduction in biosolids quantities (bulk volume) and disposal costs. The process is currently being optimised. Savings to date have reached about AUD 80,000 per month. Technical and operational issues which emerged during commissioning are also described.

Distribution of 2,4-D in air and on surfaces inside residences after lawn applications: comparing exposure estimates from various media for young children.

We collected indoor air, surface wipes (floors, table tops, and window sills), and floor dust samples at multiple locations within 11 occupied and two unoccupied homes both before and after lawn application of the herbicide 2,4-D. We measured residues 1 week before and after application. We used collected samples to determine transport routes of 2,4-D from the lawn into the homes, its subsequent distribution between the indoor surfaces, and air concentration as a function of airborne particle size. We used residue measurements to estimate potential exposures within these homes. After lawn application, 2,4-D was detected in indoor air and on all surfaces throughout all homes. Track-in by an active dog and by the homeowner applicator were the most significant factors for intrusion. Resuspension of floor dust was the major source of 2,4-D in indoor air, with highest levels of 2,4-D found in the particle size range of 2.5-10 microm. Resuspended floor dust was also a major source of 2,4-D on tables and window sills. Estimated postapplication indoor exposure levels for young children from nondietary ingestion may be 1-10 microg/day from contact with floors, and 0.2-30 microg/day from contact with table tops. These are estimated to be about 10 times higher than the preapplication exposures. By comparison, dietary ingestion of 2,4-D is approximately 1.3 microg/day.

Experimental methodologies and preliminary transfer factor data for estimation of dermal exposures to particles.

Developmental efforts and experimental data that focused on quantifying the transfer of particles on a mass basis from indoor surfaces to human skin are described. Methods that utilized a common fluorescein-tagged Arizona Test Dust (ATD) as a possible surrogate for housedust and a uniform surface dust deposition chamber to permit estimation of particle mass transfer for selected dust size fractions were developed. Particle transfers to both wet and dry skin were quantified for contact events with stainless steel, vinyl, and carpeted surfaces that had been pre-loaded with the tagged test dust. To better understand the representativeness of the test dust, a large housedust sample was collected and analyzed for particle size distribution by mass and several metals (Pb, Mn, Cd, Cr, and Ni). The real housedust sample was found to have multimodal size distributions (mg/g) for particle-phase metals. The fluorescein tagging provided surface coatings of 0.11-0.36 ng fluorescein per gram of dust. The predominant surface location of the fluorescein tag would best represent simulated mass transfers for contaminant species coating the surfaces of the particles. The computer-controlled surface deposition chamber provided acceptably uniform surface coatings with known particle loadings on the contact test panels. Significant findings for the dermal transfer factor data were: (a) only about 1/3 of the projected hand surface typically came in contact with the smooth test surfaces during a press; (b) the fraction of particles transferred to the skin decreased as the surface roughness increased, with carpeting transfer coefficients averaging only 1/10 those of stainless steel; (c) hand dampness significantly increased the particle mass transfer; (d) consecutive presses decreased the particle transfer by a factor of 3 as the skin surface became loaded, requiring approximately 100 presses to reach an equilibrium transfer rate; and (e) an increase in metals concentration with decreasing particle size, with levels at 25 microns typically two or more times higher than those at 100 microns--consistent with the earlier finding of Lewis et al. for the same sample for pesticides and polycyclic aromatic hydrocarbons (PAHs).

Movement and deposition of two organophosphorus pesticides within a residence after interior and exterior applications.

Post-application temporal and spatial distributions of two organophosphorus pesticides, diazinon (O,O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate, CAS No. 333-41-5) and chlorpyrifos [O,O-diethyl-O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate, CAS No. 2921-88-2], were monitored after homeowner applications for indoor and outdoor insect control. Samples of indoor air, vacuumable carpet dust, carpet dislodgeable residues, deposits on bare floors, table tops and dinnerware, surrogate food, and residues on children's hands and toys were taken before and up to 12 days after treatments in the family room, kitchen, and child's bedroom. Results from the study demonstrate the nature and magnitude of translocation of pesticides from the areas of application to surfaces accessible for human contact and permit comparisons of potential exposures via respiration and dermal contact/oral ingestion. Potential indoor inhalation exposures were estimated to be as high as 0.5 microg/kg/day for diazinon applied indoors and 0.05 microg/kg/day for chlorpyrifos applied to the outside perimeter of the house. While ingestion of carpet dust at the rate of 100 microg/day would have added a maximum of only approximately 0.01 microg/kg/day to the daily dose, residues found on the children's hands suggest that repeated mouthing could have contributed as much as 1-1.5 microg/kg/day. These estimates are below the U.S. Environmental Protection Agency (EPA) reference dose for chlorpyrifos, but exceed those for diazinon.

Distribution of pesticides and polycyclic aromatic hydrocarbons in house dust as a function of particle size.

House dust is a repository for environmental pollutants that may accumulate indoors from both internal and external sources over long periods of time. Dust and tracked-in soil accumulate most efficiently in carpets, and the pollutants associated with dust and soil may present an exposure risk to infants and toddlers, who spend significant portions of their time in contact with or in close proximity to the floor and who engage in frequent mouthing activities. The availability of carpet dust for exposure by transfer to the skin or by suspension into the air depends on particle size. In this study, a large sample of residential house dust was obtained from a commercial cleaning service whose clients were homeowners residing in the Raleigh-Durham-Chapel Hill (Research Triangle) area of North Carolina. The composite dust was separated into seven size fractions ranging from < 4 to 500 microm in diameter, and each fraction was analyzed for 28 pesticides and 10 polycyclic aromatic hydrocarbons (PAHs). Over 20% of the fractionated dust sample consisted of particles < 25 microm in diameter. Fourteen pesticides and all 10 of the target PAHs were detected in one or more of the seven size-fractionated samples. Sample concentrations reported range from 0.02 to 22 microg/g; the synthetic pyrethroids cis- and trans-permethrin were the most abundant pesticide residue. The concentrations of nearly all of the target analytes increased gradually with decreasing particle size for the larger particles, then increased dramatically for the two smallest particle sizes (4-25 microm and < 4 microm).

A1 adenosine receptor antagonists as ligands for positron emission tomography (PET) and single-photon emission tomography (SPET).

The high affinity of 8-cyclopentyl-1,3-dipropylxanthine (CPX) for the A1 adenosine receptor (A1AR) provides a good lead for developing radioligands suitable for positron emission tomography (PET) and single-photon emission tomography (SPET). This study tested the hypothesis that the kinds of chemical modifications made in the synthesis of CPX analogues containing carbon-11, fluorine-18, or radioiodine will not alter affinity for the A1AR. This report describes the synthesis and radioligand binding assays of unlabeled CPX analogues having methyl, 2-methoxyethyl, 2-fluoropropyl, or 3-fluoropropyl substituents, respectively, at either N-1 (13a-d) or N-3 (8a-d) or an (E)-3-iodoprop-2-en-1-yl substituent at N-3 (8f). Compounds 8d,f and 13b,d antagonized the binding of [3H]CPX to the A1AR of rat brain with affinities similar to those of CPX; compound 8c was twice as potent as CPX. Analogues 8a,b and 13a were less potent than CPX, but for each the Ki of antagonism was > or = 0.5 nM. Attempts to iodinate the 8-(4-hydroxyphenyl) analogue of CPX failed, probably because the xanthine substituent strongly deactivated the phenol toward electrophilic iodination. In summary, several of the modifications of the propyl groups of CPX needed to produce ligands for imaging by PET and SPET preserve or enhance affinity for the A1AR.

Research directions in emergency medicine.

The goal of emergency medicine is to improve health while preventing and treating disease and illness in patients seeking emergency medical care. Improvements in emergency medical care and the delivery of this care can be achieved through credible and meaningful research efforts. Improved delivery of emergency medical care through research requires careful planning and the wise use of limited resources. To achieve this goal, emergency medicine must provide appropriate training of young investigators and attract support for their work. Promotion of multidisciplinary research teams will help the specialty fulfill its goals. The result will be the improvement of emergency medical care which will benefit not only the patients emergency physicians serve but also, ultimately, the nation's health.

Handwipe sampling and analysis procedure for the measurement of dermal contact with pesticides.

A handwipe sampling and analysis procedure was developed for the measurement of dermal contact to pesticides. This procedure utilizes cellulose dressing sponges wetted with 2-propanol. A two-step wiping procedure is described that ensures that the entire hand is sampled. Removal efficiency experiments show that dry residues of the pesticides chlorpyrifos and pyrethrin I are quantitatively removed from hands immediately following contact. Results suggest that the procedure may remove pesticide residues that are deeply embedded in the skin and not removed by soap-and-water washing. Extraction efficiency studies for 29 other pesticides show that the proposed extraction method may be applicable for a wide range of pesticides including phenoxy-acid herbicides. Field testing of the procedure indicates that it is easily implemented by sampling personnel and readily accepted by children.

Isolation of Helicobacter strains from wild bird and swine feces.

We report the first isolations of Helicobacter strains from wild birds and swine. Genus-specific oligonucleotide probes identified nine Cape Cod isolates from gull, tern, house sparrow, and pig feces as Helicobacter spp. and not Campylobacter spp. Antibiotic sensitivity and urease tests distinguished three phenotypes. Strains examined rapidly lost culturability under simulated natural conditions.

Evaluation of methods for monitoring the potential exposure of small children to pesticides in the residential environment.

A nine-home pilot study was conducted to evaluate monitoring methods in the field that may be used to assess the potential exposures of children aged 6 months to 5 years to pesticides found in the home environment. Several methods, some of which were newly developed in this study, were tested for measuring pesticide residues in indoor air, carpet dust, outdoor soil, and on the children's hands. Information was also collected on household characteristics, pesticides used and stored at the residence, and children's activities. Pesticides were detected at all nine study homes. With the exception of one home, at least one pesticide was detected in all matrices sampled at each house. Of the 30 target pesticides, 23 were detected during the study. The most frequently detected pesticides were chlordane, chlorpyrifos, dieldrin, hepatachlor, and pentachlorophenol. The greatest number of pesticides and highest concentrations were found in carpet dust. The results of these investigations will be discussed in terms of performance of the methods and the distribution of pesticides across the various media sampled.

Non-occupational exposures to pesticides for residents of two U.S. cities.

The Non-Occupational Pesticide Exposure Study, funded by the U.S. Environmental Protection Agency, was designed to assess total human exposures to 32 pesticides and pesticide degradation products in the non-occupational environment; however, the study focused primarily on inhalation exposures. Two sites--Jacksonville, Florida (USA) and Springfield/Chicopee, Massachusetts (USA)--were studied during three seasons: Summer 1986 (Jacksonville only), Spring 1987, and Winter 1988. Probability samples of 49 to 72 persons participated in individual site/seasons. The primary environmental monitoring consisted of 24-hr indoor, personal, and outdoor air samples analyzed by gas chromatography/mass spectrometry and gas chromatography/electron capture detection. Indoor and personal air concentrations tended to be higher in Jacksonville than in Springfield/Chicopee. Concentrations tended to be highest in summer, lower in spring, and lowest in winter. Indoor and personal air concentrations were generally comparable and were usually much higher than outdoor air concentrations. Inhalation exposure exceeded dietary exposure for cyclodiene termiticides and for pesticides used mainly in the home. Dietary exposures were greater for many of the other pesticides. Inhalation risks were uncertain for termiticides (depending on rates of degradation) but were negligible for other pesticides. The data were insufficient to support risk assessments for food, dermal contact, or house dust exposures.

Environmental equity and pesticide exposure.

Although people of color and low-income groups bear a disproportionate share of the health risks from exposure to pesticides, research attention has been meager, and data on acute and chronic health effects related to their toxic exposures are generally lacking. Increased resources are needed both to study this issue and to mitigate problems already identified. People of color should be a major research focus, with priority on long-term effects, particularly cancer, neurodevelopmental and neurobehavioral effects, long-term neurological dysfunction, and reproductive outcome. Suitable populations at high risk that have not been studied include noncertified pesticide applicators and seasonal and migrant farm workers, including children.

Retentive characteristics of dental cementation materials.

Glass ionomer, polycarboxylate, zinc phosphate, and two resin cements were tested in vitro to cement base and noble metal crowns to prepared extracted teeth. The cements had different retentive characteristics. Among cements, statistically significant tensile resistance to dislodgment in order of decreasing strength was: (1) C & B Metabond (resin); (2) Panavia (resin); (3) Fuji I (glass ionomer); (4) Durelon (polycarboxylate); and (5) Fleck's (zinc phosphate). Tensile resistance to dislodgment did not differ statistically among base and noble metal crowns cemented with glass ionomer, polycarboxylate, or zinc phosphate cements. Tensile resistance to dislodgment differed statistically among base and noble crowns cemented with the resin cements (C & B Metabond and Panavia); the base metal crowns had the highest rate of retention.