A wire reclamation incinerator as a source of environmental contamination with tetrachlorodibenzo-p-dioxins and tetrachlorodibenzofurans

Evaluation of the emission characteristics of PCDD/Fs from electric arc furnaces

Distribution of PCDD/F (polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran) congeners at two electric arc furnaces (EAFs) in Taiwan is evaluated via intensive stack sampling and analysis. Two kinds of exhaust system in EAFs including stack system and shutter system are selected for measuring dioxin emissions. In addition, dioxin emissions during oxidation and reduction stages at EAF-A were characterized. Results indicate that the PCDD/F concentration of stack gas in EAF-A was 4.39 ng/Nm(3) while total Toxic Equivalent Quantity (TEQ) concentration was 0.35 ng I-TEQ/Nm(3). The PCDD/F concentration of stack gas in EAF-B was 2.20 ng/Nm(3) and the TEQ concentration was 0.14 ng I-TEQ/Nm(3). 1,2,3,4,6,7,8-H(p)CDF, OCDD and OCDF are the major contributors of the dioxin concentrations for two EAFs investigated and the percentage of PCDD/F in particulate phase increases as the chlorination level of the PCDD/F congener increases. The results obtained on gas/particulate partitioning of PCDD/Fs in flue gases prior to the APCD in EAFs indicate that more than 90% exists in particulate phase. In EAF-A, the PCDD/F concentration during oxidation stage is slightly higher than that measured during reduction stage, including the sampling points of CO converter outlet, prior to bag filter and stack. Majority of PCDD/Fs emitted from steel-making processes exists in particulate-phase (about 60-70%) at both EAFs investigated.

Halogenated aromatics from steel production: results of a pilot-scale investigation

The potential environmental impact of emissions of halogenated aromatics from the steel industry is of growing concern. It has been suggested that electric arc furnaces are the only industrial source with constant or increasing emissions of dioxins to air. Here the results are reported from a pilot plant study on how scrap composition and various treatment alternatives affect the formation and release of chlorinated and brominated aromatics. The experiments were conducted with a statistical mixture design, and it is shown that scrap composition has a significant impact on the outcome. In contrast, the various treatment schemes examined--shredding, disassembly, and briquetting--did not affect the formation and release of halogenated aromatics. Parallel experiments with injection of adsorbents showed that it is possible to reduce emissions without substantial investments, and this option is recommended as a low-cost solution.

Industrial chemicals and the horse

Poisoning resulting from exposure to a wide variety of industrial chemicals is not a common occurrence in horses, but it does happen on occasion. A wide range of toxicosis can occur from a wide range of industrial pollutants, such as dioxin, carbon tetrachloride, and tetrachloroethylene, to heavy metals, such as cadmium and zinc. The equine practitioner must consider industrial chemical toxicosis in differential diagnoses and work with a reputable veterinary diagnostic laboratory to confirm or rule out industrial chemical poisoning.

Acute neurobehavioural effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in Han/Wistar rats

The neurobehavioural effects of a single non-lethal dose (1000 micrograms/kg intraperitoneally) of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were assessed in young male Han/Wistar rats, highly resistant to acute lethality of TCDD. TCDD decreased body weight significantly compared with ad libitum fed controls. TCDD did not change the behaviour or the motility of rats in the open field test 8 days after the treatment nor did it affect the spontaneous motor activity up to 27 days after the exposure. In the elevated plus-maze test for anxiety, TCDD-treated rats did not differ from either ad libitum fed controls or pair-fed controls. In the 24-hr passive avoidance test, the learning of TCDD-treated rats did not differ significantly from that of ad libitum fed controls or pair-fed controls from 8 hr to 16 days after the treatment. TCDD did not affect the motor coordination or the maintenance of balance on the rotating rod but it impaired them slightly in the elevated horizontal bridge test 16 hr after exposure. It did not affect nociception in the hot plate test 16 hr or 8 days after the injection. The results suggest that a single sublethal dose of TCDD does not alter markedly the general behaviour of Han/Wistar rats, in contrast to its striking effect on feeding behaviour which results in a marked decrease in body weight gain.

Bronchial responsiveness in an area of air pollution resulting from wire reclamation

Spirometric data from 86 primary school children living in an area of air pollution resulting from wire reclamation incineration were analysed and compared with 92 non-exposed schoolchildren. There were lower values for forced vital capacity and forced expiratory volume and thus a higher incidence of pulmonary function abnormalities in the children in the polluted area than those in a non-polluted area. There was no significant difference in the prevalence of respiratory symptoms between these two areas when surveyed by a questionnaire. Twenty eight schoolchildren from a non-polluted area and 26 children from the polluted area, who were said to have no respiratory symptoms and for whom consent forms were obtained, were recruited for a bronchial responsiveness test. Nine (35%) of 26 children in the polluted area were responders (less than 50 U) and only one of the control subjects was a responder. The mean (SD) log cumulative dose producing a 35% decrease in respiratory conductance and the minimum cumulative dose required to decrease respiratory conductance from the baseline in the children of the polluted area were significantly lower than that of the control subjects (1.32 (0.37) log units and 1.26 (0.44) log units, respectively, compared with 1.70 (0.10) log unit for both measurements in non-exposed children). These results indicate that air pollution resulting from wire reclamation can produce a detrimental effect on both pulmonary function and bronchial responsiveness in primary schoolchildren who are continually exposed to air pollutants from the time of their birth.

Effects of air pollution resulting from wire reclamation incineration on pulmonary function in children

This study evaluated the effect of long-term air pollution resulting from wire reclamation incineration on pulmonary function in children. General physical examination and the determination of spirometric parameters, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and forced mid-expiratory flow (FEF25-75%) were conducted in 400 primary school children between ages 9 and 11 years who reside in one control and three polluted areas. A survey using ATS-DLD-78-C questionnaire indicated that there were no significant differences in their demographic characteristics among children in the four areas under study. Those who had nonrespiratory diseases that might affect pulmonary function and those who failed to perform spirometric measurements were excluded from the study; therefore, 382 children were included in data analysis. The results revealed that (1) the mean values of FVC and FEV1 (expressed as percentage of predicted values calculated from Polgar's equations) in the polluted areas were significantly lower than the nonpolluted area (p less than 0.05), and (2) the incidence of pulmonary function abnormality in the polluted areas was greater than that of the nonpolluted area (p less than 0.05). The results indicated that air pollution produced by wire reclamation incineration can impair children's pulmonary function.

Evaluation of potential transmission of 2,3,7,8-tetrachlorodibenzo-p-dioxin-contaminated incinerator emissions to humans via foods

Interest in the potential sources of human exposure to TCDD (dioxins, TCDD and equivalents, or 2,3,7,8-tetrachlorodibenzo-p-dioxin) via foods has recently shifted from phenoxy herbicides to products of combustion and waste disposal. Proposals to locate municipal waste combustors in rural areas have raised concerns that emissions, which could contain TCDD, could contaminate animal feeds and such human foods as milk, meat, and vegetables. Important factors that can affect the results of an assessment of incinerator emissions include (1) the emission and deposition rates of TCDD from the source, (2) the fractional retention and half-life of fly ash on plants, (3) the environmental half-life of TCDD, (4) the animal feeding and management systems, (5) the bioavailability of TCDD and related compounds, (6) the metabolism and pharmacokinetics of TCDD in farm animals, (7) food consumption levels, (8) the half-life of TCDD in humans, and (9) the model selected to estimate cancer risk. For persons living in the area of highest deposition near an incinerator, a possible uptake of TCDD from foods of animal origin was estimated to be about 10-40 fg/kg.d, which was much greater than the 1-5 fg/kg.d uptake estimated for foods of plant origin. The total uptake of TCDD from foods by the maximally exposed population will usually be about 500- to 1000-fold greater than that due to inhalation. Although milk was assumed to be the most important food pathway in several previous assessments that evaluated the hazards of airborne emissions, we determined that the deposition-forage-cattle-beef pathway was the more important route of exposure. The previous assessments appear to have used inappropriate pharmacokinetic models for TCDD and to have overestimated pasture use for dairy cows. The amount of TCDD accumulated in soil from airborne emissions was found to be less important than the amount deposited in forage, a finding that is the opposite of the usual conclusions drawn for other routes of TCDD introduction into agricultural environments. Based on the assumption and parameters used in this assessment, the potential human health risks due to TCDD emissions from incinerators are insignificant compared to other background sources of TCDD. It would be desirable to measure TCDD in soil and crops around existing facilities to better evaluate this assessment, but it is likely that concentrations would be too low to reliably quantitate.