Takashi Amagai

Pollution level, phase distribution and source analysis of polycyclic aromatic hydrocarbons in residential air in Hangzhou, China

A survey of polycyclic aromatic hydrocarbons (PAHs) in residential air in Hangzhou, China, was carried out. Air samples were collected from indoor and outdoor environments during both summer and winter and analyzed for the level of 16 PAHs. The results showed total PAH contents ranging from 0.425 to 36.2 microg/m(3) with highest concentrations in the kitchen areas generally. Particulate PAHs were predominantly absorbed on PM(2.5) with proportion of 59-97% to total particulate phase, followed by PM(2.5-10) (3-24%) and PM(>10) (0-17%). PAH concentrations in indoor air of smoking residences tended to be higher than those of nonsmoking residences. Outdoor environment, Chinese conventional cooking practice, mothball emission and unknown source accounted for -10.5%, 32.8%, 71.5% and 6.2% of total PAHs in indoor air of nonsmoking residences, respectively. Outdoor environment was the fate for indoor PAHs in general, and consumed 10.5% of total PAHs. Finally, health risks associated with the inhalation of PAHs were assessed, and the results indicated that health-based guideline levels for lung cancer risk were exceeded. The largest contribution to total health risks in summer and winter was NA (72.9%) and BaP (45.2%), respectively.

Differential action of chlorinated polycyclic aromatic hydrocarbons on aryl hydrocarbon receptor-mediated signaling in breast cancer cells.

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs), which are a series of halogenated aromatic hydrocarbons, have been found in the environment. The primary step in their metabolic activation seems to be associated with aryl hydrocarbon receptor (AhR)‐mediated induction of the cytochrome P450 (CYP) 1 family, although the evidence remains unclear. In this study, we first investigated the effects of five ClPAHs with three to five rings and the corresponding parent PAHs on the expression of CYP1A1 and 1B1 in human breast cancer MCF‐7 cells. For the targeted ClPAHs, Western blot analysis of ClPAH‐induced CYP1A1 and 1B1 showed an enhancement in activities in comparison with induction by the corresponding parent PAHs, and the effects of chlorination were especially prominent in phenanthrene. In a further study, using 6‐chlorobenzo[a]pyrene (6‐ClBaP), cotreatment with 17β‐estradiol showed an increase in the expression of CYP1B1 mRNA but not CYP1A1 mRNA. Since the AhR ligand has been reported to induce formation of an AhR‐estrogen receptor (ER) complex, which stimulates transcription of ER target genes, the effects of ClPAHs in MCF‐7 cells transfected with estrogen response elements‐regulated green fluorescent protein (GFP) reporter genes were also investigated in this study. 6‐ClBaP induced a dose‐dependent increase in GFP expression related to ER signaling through AhR activation in the cells, but 3,9,10‐trichlorophenanthrene (3,9,10‐Cl3ClPhe) did not, despite its ability to activate AhR. Furthermore, we investigated the effect of ClPAHs on the expression of the endogenous ER‐responsive genes, cathepsin D, in MCF‐7 cells. 6‐ClBaP stimulated expression of the ER‐responsive genes but 3,9,10‐Cl3ClPhe did not, as in the GFP expression system. These results suggest that estrogenic action mediated ER signaling through AhR activation does not necessarily occur for every ligand that can activate AhR.

A simple method for screening emission sources of carbonyl compounds in indoor air

Volatile organic compounds (VOCs) emitted from building and furnishing materials are frequently observed in high concentrations in indoor air. Nondestructive analytical methods that determine the main parameters influencing concentration of the chemical substances are necessary to screen for sources of VOC emissions. Toward this goal, we have developed a new flux sampler, referred to herein as an emission cell for simultaneous multi-sampling (ECSMS), that is used for screening indoor emission sources of VOCs and for determining the emission rates of these sources. Because the ECSMS is based on passive sampling, it can be easily used on-site at a low cost. Among VOCs, low-molecular-weight carbonyl compounds including formaldehyde are frequently detected at high concentrations in indoor environments. In this study, we determined the reliability of the ECSMS for the collection of formaldehyde and other carbonyl compounds emitted from wood-based composites of medium density fiberboards and particleboards. We then used emission rates determined by the ECSMS to predict airborne concentrations of formaldehyde emitted from a bookshelf in a large chamber, and these data were compared to formaldehyde concentrations that were acquired simultaneously by means of an active sampling method. The values obtained from the two methods were quite similar, suggesting that ECSMS measurement is an effective method for screening primary sources influencing indoor concentrations of formaldehyde.

Evaluation of chlorinated benz[a]anthracene on hepatic toxicity in rats and mutagenic activity in Salmonella typhimurium

Chlorinated benz[a]anthracenes (Cl‐BaA) are halogenated aromatic compounds (typified by dioxins) found in the environment at relatively high concentrations. Fischer 344 rats were intragastrically administered 0, 1, or 10 mg of Cl‐BaA or its parent compound benz[a]anthracene (BaA) per kg of body weight for 14 consecutive days. Both chemicals at 10 mg/kg/day inhibited the gain in body weight, and consequent increase in relative liver weight. Hepatic gene expression of cytochrome P450 (CYP) 1A1, 1A2, and 1B1 was significantly stimulated by administration of BaA (10 mg/kg/day) compared with the control. After administration of Cl‐BaA, only the CYP1A2 gene was significantly induced, even at the lower dosage; CYP1A1 and 1B1 mRNA levels remained unchanged in Cl‐BaA‐treated rats compared with controls. To elucidate the role of such Cl‐BaA exposure and induced CYPs at toxicity onset, we investigated the mutagenicity of BaA and Cl‐BaA using Salmonella typhimurium TA98 and TA100. BaA and Cl‐BaA at 10 μg/plate produced positive results in both strains in the presence of rat S‐9. Incubation of Cl‐BaA with recombinant rat CYP1A2 produced a significantly higher number of revertant colonies in TA98 and TA100 than in controls, but no such change was observed for BaA. In conclusion, BaA changes its own physiological and toxicological actions by its chlorination; (1) daily exposure to Cl‐BaA selectively induces hepatic CYP1A2 in rats and (2) Cl‐BaA induces frameshift mutations in the presence of CYP1A2, although BaA does not exert mutagenicity. This indicates that CYP1A2 may metabolize Cl‐BaA to active forms.

Comparison of polycyclic aromatic hydrocarbon pollution in Chinese and Japanese residential air

Comparative studies on polycyclic aromatic hydrocarbon (PAH) pollution in residential air of Hangzhou (China) and Shizuoka (Japan) were conducted in summer (August, 2006) and winter (January, 2007). Total concentrations of 8 PAHs ranged from 7.1 to 320 ng/m3 and 0.15 to 35 ng/m3 in residential air of Hangzhou and Shizuoka, respectively. Air PAH concentrations in smoking houses were higher than that in nonsmoking houses. In nonsmoking houses, mothball emission and cooking practice were the emission sources of 2- and 3-ring PAHs in Hangzhou, respectively. The 2- and 3-ring PAHs were from use of insect repellent, kerosene heating and outdoor environment in nonsmoking houses in Shizuoka. The 5- and 6-ring PAHs in residential air were mainly from outdoor environment in both cities. Toxicity potencies of PAHs in residential air of Hangzhou were much higher than that in Shizuoka.

Emission Sources and their Contribution to Indoor Air Pollution by Carbonyl Compounds in a School and a Residential Building in Shizuoka, Japan

A simple method for screening indoor emission sources of carbonyl compounds developed previously by the authors was used for this study. The new device, which is called “emission cell for simultaneous multisampling” (ECSMS), was used for flux sampling of volatile carbonyl compounds from surfaces of building and furnishing materials in situ. Indoor carbonyl concentrations in various rooms at a school and residential building in Shizuoka, Japan, were investigated in 2006 using the developed techniques. In several rooms, formaldehyde concentrations exceeded the air quality guideline value (100 µg m−3) set by the World Health Organization. The formaldehyde emission rates from the various surfaces in those rooms were determined using the ECSMS units. The furniture was found to be the major emission source of formaldehyde emission in many of the rooms; emissions from the furniture accounted for 42–79% of each room’s total emissions. On the basis of the results, a strategy to reduce the indoor formaldehyde concentrations in each room is proposed by this paper. This study confirmed that the ECSMS can be used for on-site screening of primary emission sources of formaldehyde that could cause indoor air pollution.