Evaluation of the genotoxicity of PM2.5 collected by a high-volume air sampler with impactor.

BACKGROUND: The harmful effects of fine particles with an aerodynamic diameter less than 2.5 µm (PM2.5) on respiratory organs are emphasized in pollution studies because PM2.5 have high deposition rates in the respiratory organs and contain various hazardous compounds. In this study, a sampling method combining a high-volume air sampler (HV) with a PM2.5 impactor was developed for collecting large quantities of PM2.5. The concentrations of elemental carbon (EC), organic carbon (OC), inorganic ions, and polycyclic aromatic hydrocarbons (PAHs) were measured in PM2.5 collected by the high-and low-volume air samplers (LV). RESULTS: Similar results were obtained from the HV and LV methods, with respect to inorganic carbon, organic carbon, sodium ions, ammonium ions, and PAHs with more than four rings. Because of the much larger amount of PM2.5 could be collected by the HV method, the trace constituents, that were difficult to detect by the conventional LV method, were readily detected by the HV method. Furthermore, when the microsuspension method that was modified more sensitive Ames mutagenicity test, was used to test the PM2.5 samples at four sites, mutagenic activities were detected by strains TA100 and TA98. Most of the mutagenic activity was associated with the PM2.5 fraction and mutagenic activity in winter was greater than that in summer. CONCLUSIONS: The HV method produced results similar to those from the conventional LV method with respect to the PM2.5 components present in the atmosphere in relatively high concentrations, but its 40-fold greater flow rate enabled the detection of mutagenic compounds present in only trace concentrations.

Establishing conditions for the storage and elution of rabies virus RNA using FTA(®) cards.

The Flinders Technology Associates filter paper cards (FTA(®) cards) can be used to store nucleic acid from various samples and are easily portable. However, RNA is physicochemically unstable compared with DNA, and appropriate methods have not been established for storage and extraction of RNA from FTA(®) cards. The present study investigated the optimum conditions for storage and elution of viral RNA (vRNA) using rabies virus (RABV) applied to FTA(®) cards. When TE buffer was used, the elution rates of vRNA increased with the length of the elution time. When the cards were stored at -80 °C or -20 °C, vRNA was stable over 3 months. Degradation of vRNAs occurred following storage at 4 °C and room temperature, suggesting that RNA should be extracted from cards as soon as possible if no freezer is available. When we tried to amplify vRNA from RABV-infected animal brains applied to FTA(®) cards and stored at -80 °C for 6 months, we did not detect any amplified products with the primer set for 964 bp of RABV N gene. However, we were able to detect amplified products by increasing the elution time of vRNA from FTA(®) cards from 30 min to 24 hr or by changing the primer sets to amplify 290 bp of N gene. Thus, we recommend extending the elution time for damaged or low concentration samples in FTA(®) cards.

[Determination of tobacco-specific N'-nitrosamines in mainstream smoke from Japanese cigarettes].

OBJECTIVES: Mainstream smoke from cigarettes contains tobacco-specific N'-nitrosamines (TSNAs) listed as Group 1 and 3 carcinogens by the International Agency for Research on Cancer (IARC). Herein, we report on a method of measuring the concentrations of TSNAs in mainstream smoke from the ten top-selling Japanese cigarette brands using an ISO regime by International Organization for Standardization (ISO) and HCI regime of Health Canada. METHODS: Tar in mainstream smoke was collected on a Cambridge filter pad using a smoking machine. The filter pad was immersed in 40 mL of ammonium acetate (pH 6.8) and shaken for 30 min. The extract was then loaded into a C18 column. After washing with 5 mL of 10% methanol and eluting with 5 mL of 70% methanol, the eluate was concentrated to 1 mL for LC-MS/MS analysis. RESULTS: The concentrations of TSNAs in all cigarette brands were higher when determined using the HCI regime than when determined using the ISO regime. Furthermore, the concentrations of TSNAs measured using both the ISO and HCI regimes showed negligible correlation to the tar and nicotine concentrations indicated on package labels. The cigarette samples used in the study were categorized into four classes: ultralow-, low-, medium-, and high-yield brands, which corresponded to 1, 3-6, 8-10, and 14 mg tar/cigarette, respectively. The concentration of TSNAs in ultralow-yield cigarettes was 210 ng/cigarette, as measured using the HCI regime, which was nearly equal to that in high-yield cigarettes (180 ng/cigarette). CONCLUSIONS: Exposure to TSNAs from mainstream smoke from ultralow-yield cigarettes is comparable to that from high-yield cigarettes. To properly evaluate the risk of smoking, not only the concentrations of tar and nicotine but also those of other chemicals, including TSNAs, should be printed on package labels.

Mutagenicity and PAH contents of soil in forests or planted areas in Japan.

We investigated the behavior of mutagenic substances in the soil of forests or planted areas. Mutagenicity and concentration was examined for 16 types of PAHs in soil samples collected at a depth of 1 m in 10 forests in Iwate, Ibaraki, Tokyo, Kanagawa, Yamanashi and Shizuoka prefectures in Japan. Mutagenicity and PAHs were detected mostly in soil from the surface to a depth of 30 cm when strains TA100, TA98 and YG1024 were used. In addition, a significant correlation was not found between the concentration of BaP, and specific mutagenic activity (TA98 without S9mix, r = 0.285).

Measurement of polynuclear aromatic hydrocarbons in canine lung after alkaline decomposition.

An alkaline decomposition method employing a KOH/alcohol solution was studied, and polynuclear aromatic hydrocarbons (PAHs) contained in particles remaining in canine lung were measured. As a result, BaA, BkF, BaP, and BghiP were found. By this method, PAHs extracted from the lungs of 32 dogs were 13.0-166.0 ng (mean, 63.0 ng) for BaA, 6.6-90.2 ng (mean, 27.4 ng) for BkF, 9.8-167.4 ng (mean 47.2 ng) for BaP, and 10.8-206.0 ng (mean, 61.8 ng) for BghiP. The results showed no correlation between the age and the concentration of PAHs in the lung, but some correlation was found between the age and the lung weight (p<0.01). There were significant correlations among the concentrations of the compounds in the lung (p<0.01). These results suggest that dogs, like humans, are affected by automobile exhaust and other common generation sources of such substances.