Review of Creosote Pollution Toxicity and Possibilities of Bioremediation

Abstract

Creosote oil is a complex mixture of hydrocarbon compounds obtained from high temperature distillation of coal tar. It is used for over 100 years as a fungicide, insecticide, miticide, and sporicide to protect wood and is applied by pressure methods to wood products, primary utility poles and railroad ties. This treated wood is intended for exterior or outdoor uses only. Its commercial uses include railroad ties 70%, utility poles 15-20%, and other miscellaneous commercial uses 10-15%. Composition of the creosote depends on the source and it has typically 85% polycyclic aromatic hydrocarbons (PAHs), 10% phenolic compounds, and 5% heterocyclic. Between 20 and 40% of the total weight of typical creosote can be attributed to the 16 PAHs defined as priority pollutants by the United States Environmental Protection Agency (EPA). The production of creosote in the European Union (EU) has been estimated to be approximately 60.000-100.000 t per year. The presence of the toxic PAHs and phenolic compounds make creosote treated wood harmful for the environment at the end of its service life and direct or indirect human exposure to creosote treated wood may cause carcinogenic affect to kidney, liver, bladder, eyes and skin. In this presentation we review creosote environmental pollution toxicity and possibilities of remediation.

Ionic Liquids as Antifungal Agents for Wood Preservation

“…One of the most efficient methods for fungal attack prevention (aside from chemical functionalization, impregnation with synthetic resins or coating methods, e.g., painting) is represented by the passive or pressure impregnation with different types of preservatives [ 10 , 11 ]. Historically, oil-based preservatives (including those containing polycyclic aromatic hydrocarbons) were among the first used [ 12 ], followed by waterborne preservatives based on silicates, borates, fluorides, heavy metal ions salts (especially Zn 2+ and Cu 2+ ), metallic or metal oxide particulate dispersions, metal-heterocyclic compounds complexes, or salts of arsenic/arsenous acid [ 13 , 14 , 15 ]. These formulations generally represent efficient antifungal formulations in terms of considerably extending the lifecycle of wood end-products on a mid or long-term level, but possess significant shortcomings such as relatively high toxicity (aside from silicates and some borates), and a moderate to high leaching potential [ 16 , 17 , 18 ].…”

Modification of the Bacterial Cell Wall—Is the Bioavailability Important in Creosote Biodegradation?

“…The effectiveness of biodegradation depends on the chemical structure of creosote components, their concentration, as well as on the age of the contaminant [2]. Low molecular weight PAHs (consisting of two and three rings) are faster removed than the compounds of high molecular weight [32][33][34]. Naphthalene, a two-ringed PAH, is degraded relatively easily [35].…”

Metataxonomic analyses reveal differences in aquifer bacterial community as a function of creosote contamination and its potential for contaminant remediation

“…Its composition varies according to the origin of coal and manufacturing processes, but generally is composed of approximately 85% polycyclic aromatic hydrocarbons, 10% phenolic compounds and 5% N, S and O heteroaromatics 2,8 , besides the monoaromatic hydrocarbons benzene, toluene, ethylbenzene and xylenes (BTEX) 9 . This contamination type deserves further attention given that about 20–40% of creosote-prevalent PAHs correspond to the 16 PAHs listed as priority pollutants by the US-EPA (United States Environmental Protection Agency), due to their recalcitrant, bioaccumulative character and their toxic, genotoxic, immunotoxic and carcinogenic properties 2,7,10 .…”

“…Therefore, creosote residues represent a threat to all biotic compounds of ecosystems and the contaminated sites are considered a priority for remediation 4,6,10 . Among the available remediation technologies, the use of microorganisms with ability to degrade and detoxify environmental contaminants, named bioremediation, has been highlighted 18,19 .…”

“…Bioremediation is an appealing approach to dealing with environmental contaminants as it often results in removal of a contaminant through natural biological processes. Diverse studies have revealed that, under certain conditions, most PAHs are susceptible to microbial degradation 10,20 , including bacteria belonging to the Pseudomonas , Acinetobacter , Sphingomonas , Bacillus , Enterobacter , Mycobacterium , Rhodococcus and Arthrobacter genus 10,21 . This fact has led to an increase in the application of the bioremediation approach in the restoration of environments contaminated by PAHs 7,22,23 .…”