Certification of a long-term sampling system for PCDFs and PCDDs in the flue gas from industrial facilities

AMESA (adsorption method for sampling of dioxins) is a fully automatic system for long term monitoring of dioxin emissions from industrial processes based on the adsorption method. The system has been tested and undergoing a certification procedure according to the German guidelines for certification of systems for continuous monitoring of special substances. The certification covered parameters such as disposability of the system, reproducibility of the results and comparability of the sampling method with German and European standard methods. Furthermore break through, blanks and sample storability were investigated. The results prove that AMESA is a state of the art sampling system for continuous monitoring of dioxin/furan emissions.     

Results of an "emergency quality control study" as confirmation of a PCDD/PCDF-contamination of milk and butter samples

Elevated PCDD/F levels in four butter samples and one milk sample had to be confirmed under considerable time pressure. These samples should demonstrate a raising dioxin contamination in different regions of Germany caused by the use of Brazilian citrus pulp as feedstuff. Above all, the increase of 2,3,7,8-TCDD and 1,2,3,7,8-PeCDD had to be confirmed. Thus, an "emergency quality control study" was performed including five laboratories from the official food control in Germany. The results had to be reported about two to three weeks after the first announcement of the samples (including time for shipment). The five laboratories applied different extraction and clean-up methods, used different GC-columns and GC/MS-equipment and different standard solutions. The results are in a good agreement. Slightly different results for most individual congeners were of minor importance. A difference was observed only in the 2,3,7,8-TCDF content of one laboratory which was not relevant for the evaluation of the increase of the dioxin contamination in milk and dairy products. The laboratory's individual methods proved to give correct results even under a very tight schedule.     

Dioxins: WHO's tolerable daily intake (TDI) revisited

In December 1990, the World Health Organization (WHO) established a tolerable daily intake (TDI) of 10 pg/kg b.w. (body weight) for TCDD, based on liver toxicity, reproductive effects and immunotoxicity in experimental animals, and making use of kinetic data in humans and experimental animals. Since then new epidemiological and toxicological data have emerged, in particular with respect to neurodevelopmental and endocrine effects of dioxin. Therefore, the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly organized a consultation on the "Assessment of the health risk of dioxins: re-evaluation of the TDI", May 1998, Geneva, Switzerland. The participants discussed the health risks for infants, cancer and non-cancer endpoints in humans and animals, mechanistic aspects, kinetic behaviour, modelling, exposure, and the applicability of the toxic equivalency (TEQ) concept. For the health risk assessment of dioxin-like compounds, the WHO Consultation focused on the most sensitive effects that are considered adverse (hormonal, reproductive and developmental effects) seen at low doses in animal studies (rats and monkeys). Human daily intakes corresponding with body burdens similar to those associated with adverse effects in animals could be estimated to be in the range of 14-37 pg/kg b.w./day. To arrive at a TDI expressed as TEQ, a composite uncertainty factor of 10 was recommended. By applying this uncertainty factor a TDI range of 1-4 pg TEQs/kg body weight was established. An extensive executive summary of the results of this WHO Consultation with all the underlying background documents will be published in Food Additives and Contaminants (in press).     

Decrease of PCDD/F levels in human blood from Germany over the past ten years (1989-1998)

744 whole blood samples of normal subjects from Germany collected in 1989-1998 have been analyzed for polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) by capillary gas chromatography/high resolution mass spectrometry. Over the examined time period a continuous decrease of the PCDD/F concentrations in human blood was observed. The mean levels found were 43.7 pg I-TEq/g (lipid basis) in 1989 and 20.7 pg I-TEq/g (lipid basis) in 1996/98 [median: 42.2 and 19.4]. The reduction to about the half was found for most congeners. Each one-year subset of the collective and the entire collective shows a positive correlation of the PCDD/F blood levels with age for most of the congeners, the sum values and the calculated toxicity equivalents. For statistical evaluation a multiplicative model was used: Concentration = A x Age(B). The correlation is mostly pronounced for lower chlorinated PCDD and for 2,3,4,7,8-PentaCDF. The PCDD/F concentrations in human blood in relation to the year of examination and the age of the subjects can be described by a linear model: I-TEq [pg/g (lipid basis)] = 6176 - 3.097 x Year + 0.6482 x Age or by a multiplicative model: I-TEq [pg/g(lipid basis)] = 10(89.08-0.04415 x Year + 0.008468 x Age).     

Levels of toxaphene congeners in fish from Danish waters

The levels of toxaphene congeners, in addition to PCB congeners and organochlorine pesticides, were determined in various fish samples from different Danish waters. While PCB-153 and p,p'-DDE show different levels depending on the fishing area, with highest levels in fish from the Western Baltic Sea, toxaphene was detected in all the samples investigated at a more constant level. The distribution of the three toxaphene congeners Parlar #26, #50 and #62 depends on the fishing area, with the Western Baltic Sea being different from the other waters by having almost equal levels of toxaphene congeners #26 and #50.     

Effect of methyl tertiary butyl ether concentrations on exhaust emissions from gasoline used in the metropolitan area of Mexico City

In this work, the primary objective was to assess the impact of oxygenated fuel on the exhaust emissions from an important fraction of vehicles in the Metropolitan Area of Mexico City (MAMC). The results aim to provide information on the actual effect of MTBE on a fleet that represents more than 60% of the in-use vehicles in the MAMC. Ten vehicles were tested with a low-octane base gasoline, and 10 more with a regular-grade unleaded base gasoline. Three MTBE concentrations, 5, 10, and 15 vol %, were tested following the U.S. Federal Test Procedure (FTP). CO, total HC, and NOx from the exhaust gases were quantitatively evaluated and also characterized for FTP speciated organic emissions. From this data, the O3-forming potential of the fuels was calculated. Results show that for the fleet using low-octane gasoline, the addition of 10% MTBE substantially reduced CO emissions, but total HC concentration in the exhaust showed a modest decrease. For the regular gasoline, the 10% MTBE blend seemed to be the best choice, but there was not a significant decrease in emissions. The specific reactivity of each fuel, expressed in grams of O3 per gram of nonmethane organic gases, increased with MTBE concentration in both cases. This result is important to consider, especially for a region like Mexico City, which has high atmospheric O3 concentrations.     

Costs, emissions reductions, and vehicle repair: evidence from Arizona

The Arizona inspection and maintenance (I/M) program provides one of the first opportunities to examine the costs and effectiveness of vehicle emission repair. This paper examines various aspects of emission reductions, fuel economy improvements, and repair costs, drawing data from over 80,000 vehicles that failed the I/M test in Arizona between 1995 and the first half of 1996. We summarize the wealth of data on repair from the Arizona program and highlight its limitations. Because missing or incomplete cost information has been a serious shortcoming for the evaluation of I/M programs, we develop a method for estimating repair costs when they are not reported. We find surprising evidence that almost one quarter of all vehicles that take the I/M test are never observed to pass the test. Using a statistical analysis, we provide some information about the differences between the vehicles that pass and those that do not. Older, more polluting vehicles are much more likely never to pass the I/M test, and their expected repair costs are much higher than those for newer cars. This paper summarizes the evidence on costs and emission reductions in the Arizona program, comparing costs and emissions reductions between cars and trucks. Finally, we examine the potential for more cost-effective repair, first through an analysis of tightening I/M cut points and then by calculating the cost savings of achieving different emission reduction goals when the most cost-effective repairs are made first.     

Speciated hydrocarbon emissions from small utility engines

Partially speciated hydrocarbon (HC) emissions data from several small utility engines, as measured by a Fourier Transform Infrared analyzer, are presented. The engines considered have nominal horsepower ratings between 3.7 and 9.3 kW. Both side-valve and overhead-valve engines are studied, and four different fuels are used in the engines. The results indicate that the small HCs present in the exhaust tend to be in the form of either methane or unsaturated HCs. Other small alkanes, such as ethane and propane, are present in only relatively small concentrations. In terms of ozone formation potential, the HCs in the form of methane will lead to little ozone, but the distribution of the C2 and C3 species is not ideal from an ozone reduction stand-point. It is also found that the presence of oxygen in the fuels appears to lead to somewhat more complete combustion, although the effects are not large. Finally, the overhead-valve engines appear to have lower HC emissions than side-valve engines, which is primarily due to higher operating A/F ratios and the engine geometry.     

Impact of long-term pesticide applications on some soil biological parameters

The soil oxidative and anaerobic processes, as well as, the microbial biomass were followed during three years in a cotton farm (Tatuí) where the recommended pesticides have been used for several years, and in an experimental field (S?o Paulo) treated first time with the same pesticides. The oxidative process was monitored by the dehydrogenase (DHA)-activity using triphenyltetrazolium chloride (TTC) as substrate. The anaerobic process was followed by the iron-oxide reduction, and the microbial biomass was estimated by the substrate (glucose)-indiced respiration. Increases in DHA-activity and in the microbial biomass occurred only in the farm soil, with concomitant decreases in iron-reduction. In the experimental field soil, the increases in DHA-activity were followed only by decreases in iron-reduction. Soil characteristics were the determining factor for different biological parameters after pesticide inputs. All the pesticides produced at least one clear but transient effect.     

Development of a risk assessment methodology for evaluating potential impacts associated with contaminated mud disposal in the marine environment

In order to assess impacts associated with disposal of contaminated mud arising from Hong Kong's dredging and reclamation projects, a methodology has been formulated to determine the level of risk posed by consumption of seafood/marine prey species to humans and to the Chinese White Dolphin (Sousa chinensis). This methodology improves on previously used techniques by incorporating risks for organic contaminants, accounting for doses from sources other than seafood, and incorporating additional local knowledge on Sousa chinensis behaviour. It thus represents an advance in risk assessment techniques and a new integration of risk assessment and monitoring in environmental management.