Organic halogens in the environment: studies of environmental biodegradability and human exposure.

Abstract

Organic halogens from chlorobleaching of kraft pulp were not as biorecalcitrant as has been assumed. Fifty percent were removed during biotreatment of wastewater, and 50% of the remaining organohalogens faded in fresh water ecosystems in 200 to 400 days. Molecular size seemed not to hinder biodegradation up to sizes of approximately 2000 daltons. Anoxic biodegradation was of prime importance for halomineralization of pulp bleaching organohalogens but could also lead to toxic metabolites such as vinyl chloride from tri- and tetrachloroethene in anoxic soil. Indigenous soil microbes were unable to clean old organohalogen pollution but had converted chlorophenols into polymeric substances, chlorohumus, which were found bioaccumulable by earthworms in spite of the large (up to 5000 g/mole) molecular sizes. Because of the danger of formation of toxic metabolites, the biochemistry of the xenobiotic degradation must be elucidated before active bioremediation is practiced on polluted soil or water. Groundwater pollution by chlorophenols led to increased disease among the exposed population in one well-studied case. Two further cases of potential environmental health impact are described.

Dechlorination of Commercial PCBs and Other Multiple Halogenated Compounds by a Sediment-Free Culture ContainingDehalococcoidesandDehalobacter

“…In this study, an enrichment culture AD14 was successfully established for extensive dehalogenation of Aroclor 1260 and the common coexisting halogenated compounds, e.g., PBDEs, PCE, 1,2-DCA, and 2,4,6-TCP. Although PBDEs were widely detected as cocontaminants at PCB contaminated sites, − no culture has been reported to dehalogenate both PCB and PBDE mixtures. PCB dechlorinators in culture AD14 are capable of extensively dehalogenating multiple compounds that are common contaminants in groundwater and sediments, e.g., PBDEs, 2,4,6-TCP, PCE, and 1,2-DCA.…”

“…For example, an exponential increase in the concentrations of PCBs and polybrominated diphenyl ethers (PBDEs) was found in dolphins and sharks from Florida coastal waters based on a 10-year period study . A more troublesome problem is that many PCB-contaminated sites are cocontaminated by other various halogenated compounds such as PBDEs , and chloroethenes, posing challenges to the bioremediation strategies.…”

Family Tree for Aqueous Organic Redox Couples for Redox Flow Battery Electrolytes: A Conceptual Review

“…However, some similarities regarding the toxicological behavior have been observed related to the appearance of a given moiety in an organic molecule. The introduction of a halogen atom into organic compounds is generally associated with an increase in the toxicity of the obtained derivative [90,91]. Moreover, the bigger number of halogen substituents potentially increases the health hazards from the given analogue molecule.…”

Stoffmonografie Chlorphenole ? Referenzwerte

“…In industriell belasteten Böden können die Chlorphenole in Konzentrationen bis zu 100 µg/kg Trockensubstanz vorkommen [33]. Im Umfeld der holzverarbeitenden Industrie (Sägewerke) wurden in den 1980er-Jahren in Finnland zum Teil hohe Chlorphenolkonzentrationen im Boden, im Wasser und im Sediment festgestellt [34,35,36].…”