Michael Wilken

Effectiveness of Activated Carbon and Biochar in Reducing the Availability of Polychlorinated Dibenzo-p-dioxins/Dibenzofurans in Soils

Five activated carbons (ACs) and two biochars were tested as amendments to reduce the availability of aged polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs) in two soils. All sorbents (ACs and biochars) tested substantially reduced the availability of PCDD/Fs measured by polyoxymethylene (POM) passive uptake and earthworm (E. fetida) biouptake. Seven sorbents amended at a level of 0.2 × soil total organic carbon (0.2X) reduced the passive uptake (physicochemical availability) of total PCDD/Fs in POM by 40% to 92% (or toxic equivalent by 48% to 99%). Sorbents with finer particle sizes or more macropores showed higher reduction efficiencies. The powdered regenerated AC and powdered coconut AC demonstrated to be the most effective and the two biochars also performed reasonably well especially in the powdered form. The passive uptake of PCDD/F in POM increased approximately 4 to 5 fold as the contact time between POM and soil slurry increased from 24 to 120 d while the efficacy of ACs in reducing the physicochemical availability remained unchanged. The reduction efficiencies measured by POM passive uptake for the regenerated AC were comparable to those measured by earthworm biouptake (bioavailability) at both dose levels of 0.2X and 0.5X. The biota-soil accumulation factor (BSAF) values for unamended soil ranged from 0.1 for tetra-CDD/F to 0.02 for octa-CDD/F. At both dose levels, the regenerated AC reduced the BSAFs to below 0.03 with the exception of two hexa-CDD/Fs. The reduction efficiencies measured by earthworm for coconut AC and corn stover biochar were generally less than those measured by POM probably due to larger particle sizes of these sorbents that could not be ingested by the worms.

Mortality Rates Among Trichlorophenol Workers With Exposure to 2,3,7,8-Tetrachlorodibenzo-p-dioxin

The authors examined 1,615 workers exposed to dioxins in trichlorophenol production in Midland, Michigan, to determine if there were increased mortality rates from exposure. Historical dioxin levels were estimated by a serum survey of workers. Vital status was followed from 1942 to 2003, and cause-specific death rates and trends with exposure were evaluated. All cancers combined (standardized mortality ratio (SMR) = 1.0, 95% confidence interval (CI): 0.8, 1.1), lung cancers (SMR = 0.7, 95% CI: 0.5, 0.9), and nonmalignant respiratory disease (SMR = 0.8, 95% CI: 0.6, 1.0) were at or below expected levels. Observed deaths for leukemia (SMR = 1.9, 95% CI: 1.0, 3.2), non-Hodgkin lymphoma (SMR = 1.3, 95% CI: 0.6, 2.5), diabetes (SMR = 1.1, 95% CI: 0.6, 1.8), and ischemic heart disease (SMR = 1.1, 95% CI: 0.9, 1.2) were slightly greater than expected. No trend was observed with exposure for these causes of death. However, for 4 deaths of soft tissue sarcoma (SMR = 4.1, 95% CI: 1.1, 10.5), the mortality rates increased with exposure. The small number of deaths and the uncertainty in both diagnosis and nosology coding make interpretation of this finding tenuous. With the exception of soft tissue sarcoma, the authors found little evidence of increased disease risk from exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Bioaccumulation of polychlorinated dibenzo-p-dioxins/dibenzofurans in E. fetida from floodplain soils and the effect of activated carbon amendment.

Laboratory studies were conducted to evaluate the bioaccumulation of aged polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil near the base of the terrestrial food chain using earthworms (E. fetida) as a model organism. This research also assessed the effect of activated carbon (AC) addition to soil on PCDD/F bioaccumulation in earthworms and passive uptake in polyoxymethylene (POM) samplers. Two soils taken from a wetland and a levee along the Tittabawassee River floodplain downstream of Midland, MI were used in this study. In the untreated soils, biota sediment accumulation factors (BSAFs) ranged from 0.17 for 2,3,7,8-TCDD to 0.02 for some of the higher chlorinated congeners, which were substantially lower than would be predicted using a conventional equilibrium partitioning model. The addition of AC to the floodplain soils generally reduced the BSAF values to lower than 0.02. Amendment of the wetland soil (having a high organic content) with 2% and 5% AC resulted in a 78 and 91% reduction of toxicity equivalent (TEQ) in earthworms, respectively. More strikingly, amendment of the natural levee soil (having a low organic content) with 2% and 5% AC showed >99% reduction of TEQ in earthworms. Also, freely dissolved aqueous concentrations of PCDD/Fs in soil slurries, as measured by equilibrium passive samplers, decreased up to 99% with AC treatment. Results of this study indicate that bioaccumulation of PCDD/Fs in earthworms from historically impacted floodplain soils is low and can be further reduced by amending with a strong sorbent.

Mortality rates among workers exposed to dioxins in the manufacture of pentachlorophenol.

Objective: We sought to determine if workers exposed to dioxins in pentachlorophenol (PCP) manufacturing were at increased risk of death from specific causes. Methods: We examined death rates among 773 workers exposed to chlorinated dioxins during PCP manufacturing from 1937 to 1980 using serum dioxin evaluations to estimate exposures to five dioxins. Results: Deaths from all causes combined, all cancers combined, lung cancer, diabetes, and ischemic heart disease were near expected levels. There were eight deaths from non-Hodgkin lymphoma (standardized mortality ratios = 2.4, 95% CI = 1.0 to 4.8). We observed no trend of increasing risk for any cause of death with increasing dioxin exposure. However, the highest rates of non-Hodgkin lymphoma were found in the highest exposure group (standardized mortality ratios = 4.5, 95% CI = 1.2 to 11.5). Conclusions: Other than possibly an increased risk of non-Hodgkin lymphoma, we find no other cause of death related to the mixture of the dioxin contaminants found in PCP.

Mortality in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin at a trichlorophenol plant in New Zealand.

Objective: We examined the overall mortality rates of 1599 workers employed between 1969 and 1988 at a New Zealand site, which manufactured trichlorophenol. Methods: We developed exposure estimates for 2,3,7,8-tetrachlorodibenzo-p-dioxin from a serum dioxin evaluation and used standardized mortality ratios (SMR) and proportional hazards models to evaluate risk from exposure. Results: Among exposed workers, deaths from total cancers (SMR = 1.1, 95% confidence intervals [CI]: 0.9–1.4), non-Hodgkin lymphoma (SMR = 1.6, 95% CI: 03–4.7), and ischemic heart disease (SMR = 1.1, 95% CI: 0.9–1.5) were slightly greater than expected, whereas deaths from lung cancer (SMR = 0.8, 95% CI: 0.4–1.5) were less than expected. We observed no significant trends with exposure levels. Conclusions: Although this study is small, we found no increasing trend of cancer or disease risk with increasing 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure with the possible exception of all cancers combined.

PCDD/PCDF balance of different municipal waste management methods

Abstract An inventory of different methods of managing municipal waste show not only incineration and disposal, but recycling techniques like composting or material recycling for e.g. metals are facing comparable dioxin problems. This result will have consequences in the public discussion about dioxin problems in waste management. A comprehensive solution for this problem cannot be achieved by end-of-the-pipe-techniques (e.g. dioxin filters in MWI), but has to go to the roots: the input of dioxins and precursor substances into waste management.

Flooding area and sediment contamination of the river Mulde (Germany) with PCDD/F and other organic pollutants

About 300 sediment, top- and subsoil samples from cross-sectional and longitudinal profiles of the flooding area of the river Mulde and its tributaries were analyzed for PCDD/F, benzenehexachloride (Σ αf a-, β-, γ- and Δ-BHC) and DDX. Though the Bitterfeld region (Germany) turned out to be an important (former) emitter of these substances, a considerable pre-contamination of the Mulde before it enters the Bitterfeld region with at least DDX and PCDD/F has to be taken into account. As sediment contamination partly reaches extreme values (ppm and higher), and as these contaminants can be remobilized into the water, the risk of a secondary contamination of other sediments and flooding areas, especially the river Elbe, cannot be excluded

Serum concentrations of chlorinated dibenzo-p-dioxins and dibenzofurans among former Michigan trichlorophenol and pentachlorophenol workers

This study examines serum levels of 2,3,7,8-substituted chlorinated dioxins and furans, and PCBs for 375 Michigan workers with potential chlorophenol exposure, 37 Worker Referents, and 71 Community Referents. The chlorophenol workers were last exposed to trichlorophenol and/or pentachlorophenol 26–62 years ago. Employees working only in the trichlorophenol units had mean lipid-adjusted 2378-tetrachlorodibenzo-p-dioxin (TCDD) levels of 15.9 ppt compared with 6.5 ppt in the Worker Referents. Employees working only in the pentachlorophenol units had mean lipid-adjusted levels for 123478-H6CDD of 16.1 ppt, 123678-H6CDD of 150.6 ppt, 123789-H6CDD of 20.2 ppt, 1234678-H7CDD of 192.6 ppt, and OCDD of 2,594.0 ppt compared with the Worker Referent levels for the same congeners of 7.5, 74.7, 8.6, 68.7, and 509.1 ppt, respectively. All furan and PCB levels among workers in the trichlorophenol and/or pentachlorophenol departments were similar to the Worker Referents. The Tradesmen who worked throughout the plant had dioxin congener profiles consistent with both trichlorophenol and pentachlorophenol exposures. PCB levels and levels of 23478-P5CDF, 123478-H6CDF, and 123678-H6CDF were also greater in these Tradesmen than in the Worker Referents. The Worker Referent group had higher levels of dioxins and furans than the Community Referents indicating the potential for exposure outside the chlorophenol departments at the site. Distinct patterns of dioxin congeners were found many years after exposure among workers with different chlorophenol exposures. Furthermore, past trichlorophenol exposures were readily distinguishable from past pentachlorophenol exposures based on serum dioxin evaluations among workers. These data can be used to better assess dioxin exposures in future health studies.

Serum dioxin levels in former chlorophenol workers

Using gas chromatography/mass spectrometry, we measured lipid-adjusted serum levels for all 2,3,7,8-substituted dioxins and furans, and four coplanar polychlorinated biphenyls in 62 workers with chlorophenol exposure and 36 workers without chlorophenol exposures working at the same plant during the same time. We oversampled among workers diagnosed with chloracne. Mean dioxin background levels from 36 nonchlorophenol workers were estimated as 6.0 parts-per-trillion (ppt) for 2,3,7,8 tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 67.5 ppt for 1,2,3,4,6,7,8 heptachlorodibenzo-p-dioxin (Hepta-CDD). We found different dioxin and furan profiles for trichlorophenol and pentachlorophenol (PCP) workers. Among trichlorophenol workers with chloracne, we found 2,3,7,8-TCDD (mean=30.5 ppt) above background levels and among PCP workers with chloracne, we found high levels of Hepta-CDD (mean=312.5 ppt) and other higher chlorinated dioxins and furans. Cumulative exposure estimates for dioxins for both 2,3,7,8-TCDD and the higher chlorinated dioxins created in the early 1980s for our epidemiology studies were highly correlated with serum dioxin levels when age and body mass index were taken into account. While workers previously diagnosed with chloracne had high serum dioxin levels, some workers without diagnosed chloracne also had high levels. Among tradesworkers with plant-wide responsibilities, we observed serum dioxins and PCB levels higher than background indicating workplace exposures. We estimate that the mean level of 2,3,7,8-TCDD present in the serum of workers on the date workplace exposure terminated was 267 ppt (ranging from 8 to 1184 ppt) assuming a 9-year half-life, 582 ppt (ranging from 10 to 2,641 ppt) assuming a 7-year half-life, and 1928 ppt (ranging from 22 to 17,847) when a toxicokinetic model is used. We conclude that our findings are consistent with other studies reporting high serum dioxin levels among chlorophenol workers after occupational exposures.

Distribution of PCDD/PCDF and other organochlorine compounds in different municipal solid waste fractions

Abstract The authors prepared 70 analyses of four waste fractions of samples taken in 1980 (A = paper + cardboards; B = Plastics, wood, leather, textile etc.; C = fine debris 8 mm), due to their content of PCDD/PCDF, and other organochlorine compounds. PCDD/PCDF contamination in I-TE was 18.3 - 383 pg/g (fraction A), 29.1 - 1370 pg/g (fraction B), 8 - 468 pg/g (fraction C) and 7.4 - 100 pg/g (fraction D). The average PCDD/PCDF content in I-TE of the analytical waste amounted to 104 pg/g, of the wet total waste to 50.2 pg/g. Patterns and possible input factors are discussed.