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Response to Comments on “Levels of Polychlorodibenzo-p-dioxins and Dibenzofurans in Crab Tissues from the Newark/Raritan Bay System” SIR: In our recent papers in Environmental Science and Technology (1, 2), we did not suggest, as is claimed in the preceding paper, that a former 2,4,5-T manufacturing facility on the lower Passaic River (now a Superfund site) is the “sole” source of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and other polychlorinated dibenzo-pdioxins and dibenzofurans (PCDD/Fs) to the Newark/ Raritan Bay Estuary and to the blue crabs (Callinectes sapidus), whose tissue we recently analyzed (1, 2). We do suggest, however, that this facility is a major source of 2,3,7,8-TCDD to the estuary. Our findings are consistent with all that has been reported in the papers we cited and with data furnished to the New Jersey Department of Environmental Protection and the U.S. Environmental Protection Agency Region II (3, 4). The authors of the preceding polemic assert that the number of sampling sites is inadequate to draw conclusions about the sources of 2,3,7,8-TCDD. Although we sampled only four sites, five to seven crabs were composited to obtain each sample, and samples were gathered at two different times of the year. Two composite samples from each site were analyzed for each sampling period. Furthermore, there is other evidence, as Iannuzzi et al. acknowledge, that there are higher levels of 2,3,7,8-TCDD in tissue samples taken more proximate to the former manufacturing site. Iannuzzi et al. “are more concerned with the fact that Cai et al. (1, 2) did not cite the numerous papers in the peer-reviewed literature which directly conflict with their claims”. The authors of the polemic refer to a “a number of comprehensive sediment and contaminant source investigations that have revealed the presence of multiple sources of PCDD/Fs to the Newark Bay Estuary”. It is informative that all the papers reporting these investigations have been authored by individuals from the same consulting group (ChemRisk) as that of Iannuzzi et al. There are reasons why it is not appropriate to cite these investigations, as is discussed in the following. The Newark Bay surficial sediment samples on which all of the referenced “investigations” (5-9) were based were selected with a bias that casts doubt on the appropriateness of any comparisons that we might have drawn with that work. Wanning et al. (9) stated that “Comparisons were conducted to determine whether the PCDD/F residues typically found in a broad range of potential environmental sources could explain the presence of these chemicals in Newark Bay. Only two surficial sediment samples, however, were taken in proximity to the former 2,4,5-T manufacturing facility on the Passaic River for these investigations. The majority of the samples were collected either above a dam approximately 16 mi upriver of the known source or in tributaries unlikely to be heavily impacted by the known manufacturing facility source. In addition, Newark Bay itself, a likely area for spread of PCDD/Fs from the former chemical manufacturing site, was scrupulously avoided in
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the sediment sampling. This bias in sampling is even more disturbing in light of the fact that the authors have access to an extensive sediment database for the former chemical manufacturing site and its vicinity (8). Avoiding sampling near a known source in attempting to relate Newark Bay PCDD/F residue patterns to other source patterns seems to us either to be the result of poor design or to be “disingenuous”. Second, the authors stated that their investigations “revealed the presence of multiple sources of PCDD/Fs to the Newark Bay Estuary”. This is an overstatement. Principal components analysis does not prove an absolute relationship between the distribution of PCDD/F in sediment samples and a putative source. It is merely a statistical methodology that attempts to relate the distribution pattern, or fingerprint, of congeners in one dataset to other patterns of congener distributions. This methodology can only serve as an indicator for those regions that were sampled. Third, the authors do not follow their own good advice to use “some caution ... when relating PCDD and PCDF residue levels to particular sources” and to consider various weathering processes that occur to PCDD/Fs once in sediment. In all their published investigations (5-9), the results are overinterpreted without taking into account the congener distribution uncertainties that are due to biotic and abiotic weathering. Iannuzzi et al. are also concerned that we (3) “failed to cite the numerous EPA studies which report the presence of TCDD sources at sites very near the Cai et al. (1) sampling locations”. Iannuzzi et al., however, refer to exactly one EPA report and one EPA memorandum. Where are the “numerous EPA studies”? Second, the authors overstate the conclusions of the EPA report. This report (10) simply presented a source-correlation analysis with aquatic organism tissue results and lists of potential regional sources. To determine an absolute relationship between PCDD/F organism tissue levels and sources in Raritan Bay will require more proof than can be obtained in a source-correlation analysis. In our second paper (2), we demonstrated a good correlation between the levels of 2,3,7,8-TCDD and another related chlorinated aromatic compound, 2,4,6,8-tetrachlorodibenzo-p-dioxin. We concluded that the correlation indicates that “the source of 2,4,6,8-TCDT may be the same as that of the 2,3,7,8-TCDD” (2). It is asserted in the foregoing polemic that our tentative conclusion is inconsistent with results of recent studies (ref 16 in the preceding paper). That report was accepted for publication after our articles had been accepted. It is informative that ref 16 presents TCDT data that were first published in one of the articles being criticized, but a correct citation was not given. Iannuzzi et al. claim that “the former 2,4,5-T facility is not a plausible current source of PCDD/Fs” because the “sediments associated with the era that the facility ceased operations are buried under approximately 1-5 m of sediment and therefore are not believed to be mobile or bioavailable”. If this is so, how do these authors explain the persistently high TCDD concentrations observed in surficial sediments collected adjacent to and in the vicinity of this facility in 1991-1993 (3). These TCDD concentrations are high in comparison to those in sediments collected
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both upriver and downriver to the facility. Furthermore, sediments will remain “buried” only in sites where there is no disturbance by man and/or by nature. Although one cannot prove conclusively that the source of the 2,3,7,8TCDD is the facility in question, one can identify circumstantial evidence that points to this facility as a major source, especially when one considers the dynamic nature of tidally influenced riverine sediments.
Literature Cited (1) Cai, Z.; Ramanujam, V. M. S.; Gross, M. L.; Cristini, A.; Tucker, R. K. Levels of polychlorodibenzo-p-dioxins and dibenzofurans in crab tissues from Newark/Raritan Bay system. Environ. Sci. Technol. 1994, 28, 1528-1534. (2) Cai, Z.; Giblin, D. E.; Ramanujam, V. M. S.; Gross, M. L.; Cristini, A. Mass-profile monitoring in trace analysis: Identification of polychlorodibenzothiophenes in crab tissues collected from the Newark/Raritan Bay system. Environ. Sci. Technol. 1994, 28, 1535-1538. (3) Analytical Data Summary Tables Related to Passaic River Study. Presented to U.S. Environmental Protection Agency Region II and New Jersey Department of Environmental Protection by ChemRisk, on behalf of Maxus Corporate Company/Occidental Chemical Corporation, Apr 22, 1993. (4) Passaic River Sediment Study. Presented to the New Jersey Department of Environmental Protection, prepared by Diamond Shamrock Chemicals Company and IT Corporation, March, 1986. (5) Finley, B.; Wenning, R. J.; Ungs, M. J.; Huntley, S.; Paustenbach, D. J. PCDDs and PCDFs in surficial sediments from the lower Passaic River and Newark Bay. Dioxin ’90 Conference Proceedings; Lewis Publishers: Chelsea, MI, 1990. (6) Wenning, R. J.; Paustenbach, D. J.; Johnson, G.; Ehrlich, R.; Harris, M.; Bedbury, H. Chemometric analysis of potential sources of polychlorinated dibenzo-p-dioxins and dibenzofurans in surficial sediments from Newark Bay, New Jersey. Chemosphere 1993, 27, 55. (7) Wenning, R. J.; Harris, M.; Finley, B.; Paustenbach, D. J.; Bedbury, H. Application of pattern recognition techniques to evaluate
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polychlorinated debenzo-p-dioxin and dibenzofuran distributions in surficial sediments from the lower Passaic River and Newark Bay. Ecotoxicol. Environ. Saf. 1993, 25, 103-125. (8) Wenning, R. J.; Paustenbach, D. J.; Harris, M.; Bedbury, H. Principal components analysis of potential sources of polychlorinated dibenzo-p-dioxin and dibenzofuran residues in surficial sediments from Newark Bay, New Jersey. Arch. Environ. Contam. Toxicol. 1993, 24, 271-289. (9) Wenning, R. J.; Harris, M.; Ungs, M. J.; Paustenbach, D. J.; Bedbury, H. Chemometric comparisons of polychlorinated dibenzo-p-dioxin and dibenzofuran residues in surficial sediments from Newark Bay, New Jersey and other industrialized waterways. Arch. Environ. Contam. Toxicol. 1992, 22, 397413. (10) National Study of Chemical Residues in Fish; U.S. Environmental Protection Agency, Office of Science and Technology: Washington, DC, 1992.
Zongwei Cai and Michael L. Gross* Department of Chemistry Washington University One Brookings Drive St. Louis, Missouri 63130
Angela Cristini Biology Department Ramapo College of New Jersey Mahwah, New Jersey 07430
Robert K. Tucker* and Ruth Prince Division of Science and Research New Jersey Department of Environmental Protection Trenton, New Jersey 08625 ES9510065
