Jean-Louis Benoit-Guyod

Hazard to man and the environment posed by the use of urban waste compost: a review

Abstract This review presents the current state of knowledge on the relationship between the environment and the use of municipal waste compost in terms of health risk assessment. The hazards stem from chemical and microbiological agents whose nature and magnitude depend heavily on the degree of sorting and on the composting methods. Three main routes of exposure can be determined and are quantified in the literature: (i) The ingestion of soil/compost mixtures by children, mostly in cases of pica, can be a threat because of the amount of lead, chromium, cadmium, PCDD F and fecal streptococci that can be absorbed. (ii) Though concern about contamination through the food chain is weak when compost is used in agriculture, some authors anticipate accumulation of pollutants after several years of disposal, which might lead to future hazards. (iii) Exposure is also associated with atmospheric dispersion of compost organic dust that convey microorganisms and toxicants. Data on hazard posed by organic dust from municipal composts to the farmer or the private user is scarce. To date, microorganisms are only measured at composting plants, thus raising the issue of extrapolation to environmental situations. Lung damage and allergies may occur because of organic dust, Gram negative bacteria, actinomycetes and fungi. Further research is needed on the risk related to inhalation of chemical compounds.

Biodegradation of three substituted phenylurea herbicides (chlortoluron, diuron, and isoproturon) by soil fungi. A comparative study.

As a part of a study conducted on the fate of xenobiotics in the environment, a selection of 90 strains of micromycetes, mostly isolated from soil and belonging to various taxonomic groups, have been cultivated in liquid synthetic medium with chlortoluron (100 mg.L-1), diuron (20 mg.L-1), and isoproturon (100 mg.L-1) for 5 days. Evaluation of the chemicals in the culture media was made by HPLC. Our results show a wide variation not only with taxonomic groups but also with the species, and with the tested chemicals. On the whole, 4, 7, and 11% of the strains depleted respectively chlortoluron, diuron, and isoproturon, at 50% or over. Rhizoctonia solani was the only strain that depleted each of the 3 substituted phenylureas over 70%, nevertheless, the growth of this fungus was slightly inhibited by diuron. The very fast disappearance of the chemicals from the culture media was only due to biotic phenomena, as no adsorption occurred on the fungal biomass. So, depletion translated a real biodegradation of the tested substrates.

Biodegradation of Anthracene by soil fungi

Abstract A selection of 39 strains of micromycetes known as good degraders of polychlorinated aromatic compounds, mostly isolated from soil and belonging to various taxonomic groups, have been investigated for anthracene degradation. Toxicity and consumption assays, first evaluated on solid media, have not shown any toxicity of anthracene (1–100 mg.L −1 ) towards fungi. Degradation of anthracene (10 mg.L −1 ) was then investigated in a liquid synthetic medium for 4 days and evaluated by HPLC. Among the 39 strains tested, 19 degraded anthracene at 50% or more. Zygomycetes appeared to be the most efficient group (mean degradation : 81%) while Melanconiales were the least efficient (mean : 14%). Among 19 efficient strains, 8 had not yet been reported in the literature : Cryphonectria parasitica, Ceriporiopsis subvermispora, Oxysporus sp., Cladosporium herbarum, Drechslera spicifera, Verticillium lecanii, Fusarium moniliforme var. subglutinans and Rhizopus arrhizus .

Biodegradation of fluoranthene by soil fungi

A selection of 39 strains of micromycetes known as good degraders of polychlorinated aromatic compounds, mostly isolated from soil and belonging to various taxonomic groups, have been investigated for fluoranthene degradation. Toxicity assays, first evaluated on solid medium MEA, have not shown any toxicity of fluoranthene (1-100 mg.L-1) towards fungi. Whereas, consumption assays on a solid synthetic medium showed a toxicity at 100 mg.L-1. The degradation of fluoranthene (10 mg.L-1) was then investigated in a liquid synthetic medium for 4 days and evaluated by HPLC. Among the 39 strains tested, 18 degraded fluoranthene at 60% or more. Zygomycetes appeared to be the most efficient group (mean degradation: 90%). Among 18 performant strains, 10 had not yet been reported in the literature: Sporormiella australis, Cryptococcus albidus, Cicinobolus cesatii, Pestalotia palmarum, beauveria alba, Aspergillus terreus. Cunninghamella blakesleeana, C. echinulata, Mortierella ramanniana and Rhizopus arrhizus. Fluoranthene adsorption on fungi was very low for the strains which degraded well fluoranthene (mean adsorption: 4%). Whereas, some strains adsorbed it much more such as Colletotrichum dematium (47%) and Penicillium italicum (43%).

Health Risk Assessment of a Modern Municipal Waste Incinerator

During the modernization of the municipal waste incinerator (MWI, maximum capacity of 180,000 tons per year) of Metropolitan Grenoble (405,000 inhabitants), in France, a risk assessment was conducted, based on four tracer pollutants: two volatile organic compounds (benzene and 1, 1, 1 trichloroethane) and two heavy metals (nickel and cadmium, measured in particles). A Gaussian plume dispersion model, applied to maximum emissions measured at the MWI stacks, was used to estimate the distribution of these pollutants in the atmosphere throughout the metropolitan area. A random sample telephone survey (570 subjects) gathered data on time-activity patterns, according to demographic characteristics of the population. Life-long exposure was assessed as a time-weighted average of ambient air concentrations. Inhalation alone was considered because, in the Grenoble urban setting, other routes of exposure are not likely. A Monte Carlo simulation was used to describe probability distributions of exposures and risks. The median of the life-long personal exposures distribution to MWI benzene was 3.2 x 10(-5) micrograms/m3 (20th and 80th percentiles = 1.5 x 10(-5) and 6.5 x 10(-5) micrograms/m3), yielding a 2.6 x 10(-10) carcinogenic risk (1.2 x 10(-10)-5.4 x 10(-10)). For nickel, the corresponding life-time exposure and cancer risk were 1.8 x 10(-4) micrograms/m3 (0.9 x 10(-4)-3.6 x 10(-4) micrograms/m3) and 8.6 x 10(-8) (4.3 x 10(-8)-17.3 x 10(-8)); for cadmium they were respectively 8.3 x 10(-6) micrograms/m3 (4.0 x 10(-6)-17.6 x 10(-6)) and 1.5 x 10(-8) (7.2 x 10(-9)-3.1 x 10(-8)). Inhalation exposure to cadmium emitted by the MWI represented less than 1% of the WHO Air Quality Guideline (5 ng/m3), while there was a margin of exposure of more than 10(9) between the NOAEL (150 ppm) and exposure estimates to trichloroethane. Neither dioxins nor mercury, a volatile metal, were measured. This could lessen the attributable life-long risks estimated. The minute (VOCs and cadmium) to moderate (nickel) exposure and risk estimates are in accord with other studies on modern MWIs meeting recent emission regulations, however.

Effects of culture parameters on the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) by selected fungi

In order to enhance 2,4-D and 2,4-DCP degradation by four selected fungi (Cunninghamella elegans, C. echinulata, Rhizoctonia solani and Verticillium lecanii), three culture parameters (initial chemical concentration, amounts of glucose and nitrogen) were varied. The levels of both xenobiotics in the culture media were monitored by HPLC analysis after five days of cultivation. The best results were obtained at low initial concentration (20 mg.L-1 vs 100) and with low amounts of glucose (5 g.L-1 vs 10) and nitrogen (2.4 mM vs 24). When these two elements were lacking from the culture media, biodegradation was not suppressed, but took place to a lesser extent. Thus, initial chemical concentration and amounts of carbon and nitrogen, in the culture medium, were shown to strongly influence the extent of 2,4-D and 2,4-DCP removal by fungi.

Degradation of pentachloronitrobenzene by micromycetes isolated from soil

Abstract A wide study has been conducted on the fate of xenobiotics in the environment and more particularly on the biodegradation of these compounds. The selection of fungal strains able to degrade pentachloronitrobenzene (PCNB) has been performed. Of the collection of strains in our laboratory 1060 were incubated with PCNB (100 mg/l) for 5 days in liquid synthetic medium. The production of extracellular phenoloxidases was examined by using ten different reagents. We found that only 3% of the strains were able to degrade PCNB by over 70%. The most performant groups were Mucedinaceeae and Zygomycetes. No correlation was found between the production of extracellular phenoloxidases and the biodegradative capability of individual strains. A detailed study of PCNB metabolism by selected strains is in progress.

Relationship between the biodegradative capability of soil micromycetes for pentachlorophenol and for pentachloronitrobenzene

A collection of 1056 strains in our laboratory were incubated with various xenobiotics among which were two potent fungicides: pentachlorophenol (PCP) and pentachloronitrobenzene (PCNB). The production of extracellular phenoloxidases were examined, using a series of ten different reagents. On the whole, PCNB is less accessible to fungal degradation than PCP. Although no correlation was found between the biodegradative capability of individual fungal strains for PCP or for PCNB, when taxonomic groups were considered as a whole, the same activity profiles were found. Zygomycetes were the most efficient; yeasts the least efficient towards both substrates. A more detailed study of the metabolism of both substrates on selected strains is in progress.

Toxicity of pentachlorophenol for micromycetes isolated from freshwater sediments

In order to evaluate the impact of xenobiotics on fungal communities of sediments, lentic ecosystems have been reconstituted in the laboratory and examined before as well as after contamination.Microcosms (2 litres) have been treated with three different concentrations of pentachlorophenol (PCP) (3, 100, and 1000 mg l-1) at 22 degC. The fungal strains present in the sediments were first isolated and identified before contamination with PCP. Most of the strains belonged to Deuteromycetes (mainly Mucedinaceæ and Dematiaceæ) with a predominance of the genus Penicillium, and Ascomycetes were found in exceptional abundance. New isolations and identifications were made on days 1, 2, 4, 8, and 15 after contamination with PCP. The sensitivity of the various species were determined as a function of the level of PCP and the duration of contamination. Ascomycetes was particularly resistant to high concentrations of PCP. The toxicity of the xenobiotic towards strains belonging to various taxonomic groups is discussed, as well as the possibility that some of them may be useful for biodegradation and/or bioremediation processes, or as bioindicators of polluted sites.