Yukihiko Takagi

Human Exposure to Airborne Mutagens Indoors and Outdoors Using Mutagenesis and Chemical Analysis Methods

The lung cancer mortality rate has been steadily increasing in industrialized countries of the world. There are many risk factors for the lung cancer induction in our environments. Airborne carcinogens and mutagens are considered to be one of the major risk factors. However, quantitative contribution of airborne carcinogens and mutagens to the lung cancer induction has not yet been accurately evaluated, because of the lack of data on long-term human exposure to these chemicals in many areas which are in different pollution levels. For this purpose, there is an urgent need to develop methodologies suitable for monitoring long-term exposure to these carcinogens and mutagens.

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.

MEASUREMENT OF CONCENTRATIONS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN SANDBOXES IN 51 JAPANESE PARKS

We investigated the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the sand of sandboxes in 51 parks in Japan. We inspected the following 10 kinds of PAHs: fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1, 2, 3,-cd]pyrene, benzo [ghi]perylene, and dibenz[a,h]anthracene. The PAHs that showed relatively high concentrations were fluoranthene and pyrene, at 17.2 ng/g sand and 14.9 ng/g sand, respectively, on average. While the total concentration of PAHs in most samples ranged from 1 to 120 ng/g sand, some samples showed concentrations of 400, 600, and even nearly 1500 ng/g sand. The composition ratios of PAHs of most samples were comparable, but some samples had distinctive composition ratios, suggesting that various sources of pollution existed. The main problem is that the infants playing in sandboxes cannot distinguish between sandboxes polluted by PAH levels of several hundred ng/g sand or a thousand ng/g sand. Therefore, it is essential to investigate the causes of the pollution of PAH and to take countermeasures.

Application of the Ultramicro Forward-Mutation Assay to the Monitoring of Indoor and Outdoor Air Mutagenicity-Examples of Chengdu City and Tokyo

Various chemicals are emitted into the air from factories, offices, incinerators, and vehicles by industrial activity (Alfhei & Mψller, 1981; Mψller et al, 1982; Watanabe & Hirayama, 1997). In addition, indoor air is polluted by chemicals used or exhausted intentionally or unintentionally during heating (use of town gas and fossil fuel), cooking, smoking and building materials (Endo et al, 2000; Koyano et al, 1999; Takagi et al, 1997). People are concerned about the health impacts of the hazardous chemicals contained in those materials. The carcinogens and mutagens detected in air can be classified into two groups: particulate matter and gas/vapor matter. Regarding particulate matter, various substances including inorganic ones such as heavy metals and organic compounds such as polycyclic aromatic hydrocarbons are detected. Such substances and compounds include polycyclic aromatic hydrocarbons (PAHs) like benzo[a]pyrene, which is now attracting attention as a carcinogenic/mutagenic substance, and dinitropyrene, which shows extremely high mutagenicity for Salmonella TA98 strain (Watanabe & Hirayama, 1997). It is widely known that PAHs are formed during the incomplete combustion of organic matter (Somenath & Wilson, 1992). PAHs are also formed when fossil fuel is burned by industry and in daily life and so the health hazards of PAHs contained in the environment cannot be avoided. People spend 80 to 90% of their time indoors, and especially infants, elderly people and sick people with a weak immune system spend even longer hours indoors. Therefore, it is important to keep the indoor environment clean because human health is greatly influenced by the environment. However, there have been few studies on the mutagenicity of indoor air because the amount of such substances that can be sampled is limited. A new mutagenicity test that is more sensitive than the existing widely-usedAmes method: “plate incorporation method” and “preincubation method” needs to be developed. We studied use of the ultramicro forward mutation Assay,

MEASUREMENT OF CONCENTRATIONS OF POLYCYCLIC AROMATIC HYDROCARBONS AND DIOXIN COMPOUNDS IN CANINE LUNGS

Polycyclic aromatic hydrocarbons (PAHs) and dioxin compounds remaining in canine lungs were measured with an alkaline decomposition method employing KOH/ethanol. PAHs extracted from the lungs of 31 dogs were between 0.07 and 0.47 ng/wet-g (mean: 0.19 ng/wet-g) for BaA; 0.03 and 0.16 ng/wet-g (mean: 0.08 ng/wet-g) for BkF; 0.05 and 0.29 ng/wet-g (mean: 0.13 ng/wet-g) for BaP; and 0.05 and 0.35 ng/wet-g (mean: 0.17 ng/wet-g) for BghiP. Dioxin concentrations were between 0.047 and 0.870 pg-TEQ/wet-g (mean: 0.179 pg-TEQ/wet-g). There were big differences between the PAH concentrations and dioxin concentrations in the canine lungs. Strong relationships were observed between individual PAHs (r = 0.73–0.95). In this study, we detected PAHs and dioxins in all samples, confirming that canine lungs were contaminated by those pollutants.