Estimation of the contribution of ultrafine particles to lung deposition of particle-bound mutagens in the atmosphere.

The present study was performed to estimate the contributions of fine and ultrafine particles to the lung deposition of particle-bound mutagens in the atmosphere. This is the first estimation of the respiratory deposition of atmospheric particle-bound mutagens. Direct and S9-mediated mutagenicity of size-fractionated particulate matter (PM) collected at roadside and suburban sites was determined by the Ames test using Salmonella typhimurium strain TA98. Regional deposition efficiencies in the human respiratory tract of direct and S9-mediated mutagens in each size fraction were calculated using the LUDEP computer-based model. The model calculations showed that about 95% of the lung deposition of inhaled mutagens is caused by fine particles for both roadside and suburban atmospheres. Importantly, ultrafine particles were shown to contribute to the deposition of mutagens in the alveolar region of the lung by as much as 29% (+S9) and 26% (-S9) for the roadside atmosphere and 11% (+S9) and 13% (-S9) for the suburban atmosphere, although ultrafine particles contribute very little to the PM mass concentration. These results indicated that ultrafine particles play an important role as carriers of mutagens into the lung.

Size distributions of polycyclic aromatic hydrocarbons in the atmosphere and estimation of the contribution of ultrafine particles to their lung deposition.

This is the first estimation of the contribution of ultrafine particles to the lung deposition of particle-bound polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The size distributions of nine PAHs (4-6 rings) were measured at roadside and suburban sites in winter in Japan. Deposition efficiencies and fluxes of PAHs in ultrafine mode (<0.12 microm), accumulation mode (0.12-2.1 microm), and coarse mode (>2.1 microm) to the human respiratory tract were calculated using the LUDEP computer-based model. From 10%-15% and 4.2%-6.9% of target PAHs were distributed in the ultrafine mode in the roadside and suburban atmosphere, respectively. The model calculations showed that as much as 18%-19% and 16%-17% of inhaled PAHs are deposited in the alveolar region of the lung for the roadside and suburban atmosphere, respectively. Total deposition fluxes of target PAHs in the alveolar region were about 1.5-fold greater for the roadside atmosphere than for the suburban atmosphere. Importantly, ultrafine particles were shown to contribute as much as 23%-30% and 10%-16% to PAH deposition in the alveolar region for the roadside and suburban atmosphere, respectively, although the contributions of ultrafine particles to the total particulate matter masswere only 2.3% in the roadside atmosphere and 1.3% in the suburban atmosphere. These results indicated that ultrafine particles are significant contributors to the deposition of PAHs into the alveolar region of the lung.

Bioremediation of the organochlorine pesticides, dieldrin and endrin, and their occurrence in the environment.

Dieldrin and endrin are persistent organic pollutants that cause serious environmental problems. Although these compounds have been prohibited over the past decades in most countries around the world, they are still routinely found in the environment, especially in the soil in agricultural fields. Bioremediation, including phytoremediation and rhizoremediation, is expected to be a useful cleanup method for this soil contamination. This review provides an overview of the environmental contamination by dieldrin and endrin, along with a summary of our current understanding and recent advances in bioremediation and phytoremediation of these pollutants. In particular, this review focuses on the types and abilities of plants and microorganisms available for accumulating and degrading dieldrin and endrin.

Isolation of dieldrin- and endrin-degrading bacteria using 1,2-epoxycyclohexane as a structural analog of both compounds.

This report describes the selective isolation of dieldrin- and endrin-degrading bacteria from soil with high degradation activity toward dieldrin and endrin. Several enrichment cultures from the soil were arranged with several structural analogs of dieldrin and endrin as a growth substrate and examined for their degradation activities toward dieldrin and endrin. An enrichment culture with 1,2-epoxycyclohexane (ECH) was found to aerobically degrade dieldrin and endrin. Denaturing gradient gel electrophoresis (DGGE) indicated that three types of bacteria were predominant in the ECH enrichment culture. Of the three major bacteria, two isolates, Burkholderia sp. strain MED-7 and Cupriavidus sp. strain MED-5, showed high degradation activity toward dieldrin and endrin. The degradation efficiencies of strain MED-7 and MED-5 were 49% and 38% toward dieldrin, respectively, and 51% and 40% toward endrin, respectively, in the presence of ECH for 14 days. These results indicated that ECH was a useful substrate for selective and efficient isolation of dieldrin- and endrin-degrading bacteria from soil containing numerous bacteria. Interestingly, the two isolates could also degrade dieldrin and endrin even in the absence of ECH. These are the first microorganisms demonstrated to grow on dieldrin and endrin as the sole carbon and energy source under aerobic conditions.

Simple and sensitive method for determination of nitrated polycyclic aromatic hydrocarbons in diesel exhaust particles by gas chromatography-negative ion chemical ionisation tandem mass spectrometry.

An extremely simple and sensitive method was developed for determination of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs; mono-nitro-PAHs and dinitropyrenes) in diesel exhaust particles (DEPs) by gas chromatography-negative ion chemical ionisation tandem mass spectrometry (GC/NCI/MS/MS). We used two types of column in GC/NCI/MS/MS analysis. A polar column was used for determination of mono-nitro-PAHs, and a non-polar column was used for determination of dinitropyrenes and mono-nitro-PAHs except nitrofluoranthenes. The proposed method requires no clean-up procedure. The limits of detection ranged from 0.01 to 0.09 pg for all compounds tested. The applicability of the method to DEP samples was validated using diesel particulate standard reference materials (SRMs). Although DEPs contain complex matrices, all compounds could be detected easily in SRM2975 (diesel particulate matter) and SRM1975 (diesel particulate extract) without a clean-up procedure. The RSDs were less than 5% for all compounds examined. The quantitative results for SRMs exhibited good agreement with the available data in the literature. These results indicate that the proposed GC/NCI/MS/MS method is useful for determination of nitro-PAHs in DEP samples.