Change over time of the mutagenicity in the lungs of gpt delta transgenic mice by extract of airborne particles collected from ambient air in the Tokyo metropolitan area.

BACKGROUND: Previously we found that DNA adducts were accumulated in the lungs of the rats exposed to ambient air in the Tokyo metropolitan area. To examine chronological change in in vivo mutagenicity of airborne particles, extracts produced from samples of total suspended particulates (TSP) collected from urban air in 1980, 1990, and 2010 in the Tokyo metropolitan area were intratracheally administered into the lungs of gpt delta mice, and differences in mutation and mutant frequency were determined by using the gpt assay. In vivo mutations induced by the extracts were characterized and mutation hotspots were identified by DNA sequencing of the mutated gpt gene. RESULTS: Administration of the 1990 extract at a dose of 0.3 mg/animal significantly elevated total mutant frequency to 3.3-times that in vehicle control, and the in vivo mutagenicity of the extract (induced mutation frequency per milligram extract) was estimated to be 2.0- and 2.4-times higher than that of the 2010 and 1980 extract, respectively. G-to-A transition was the most common base substitution in the vehicle control mice. However, administration of the 1990 extract increased the frequency of G-to-T transversion, which is a landmark base substitution induced by oxidative stress; furthermore, when the extract was administered at a dose of 0.15 mg, the mutant and mutation frequencies of G-to-T transversion were significantly increased to frequencies comparable with those of G-to-A transition. Similar increases in the mutant and mutation frequencies of G-to-T transversion were observed after administration of the 2010 extract. Hotspots (mutation foci identified in three or more mice) of G-to-A transition mutations at nucleotides 64 and 110 were induced by the 1980, 1990, and 2010 extracts; a hotspot of G-to-T transversions at nucleotide 406 was also induced by the 2010 extract. Previously, we showed that diesel exhaust particles or their extract, as well as 1,6-dinitropyrene, administered to mice induced these hotspots of G-to-A transitions. CONCLUSIONS: The results of the present study suggested that mutagenesis induced by extracts produced from TSP collected in the Tokyo metropolitan area induced in vivo mutagenicity via the same mechanism underlying the induction of in vivo mutagenicity by components of diesel exhaust.

Long term trends in atmospheric concentrations of polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons: A study of Japanese cities from 1997 to 2014.

Total suspended particulate matter (TSP) was collected during the summer and winter in five Japanese cities spanning Hokkaido to Kyushu (Sapporo, Kanazawa, Tokyo, Sagamihara and Kitakyushu) from 1997 to 2014. Nine polycyclic aromatic hydrocarbons (PAHs) with four to six rings, including pyrene (Pyr) and benzo[a]pyrene (BaP), were identified using high-performance liquid chromatography (HPLC) with fluorescence detection. Two nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1-NP) and 6-nitrobenzo[a]pyrene (6-NBaP), were identified by HPLC with chemiluminescence detection. A comparison of PAH and NPAH concentrations and [NPAH]/[PAH] ratios such as [1-NP]/[Pyr] and [6-NBaP]/[BaP] revealed the following characteristics in the five cities: (1) In Sapporo, Kanazawa, Tokyo and Sagamihara, the concentrations of PAHs and NPAHs were high at the beginning of the sampling period and then steadily decreased, with NPAHs decreasing faster than PAHs. The large initial [1-NP]/[Pyr] ratios suggest that the major contributor was automobiles but subsequent decreases in this ratio suggest decreased automobile contributions. (2) By contrast, PAH concentrations in Kitakyushu did not decrease during the sampling period, though concentrations of NPAHs decreased. The consistently smaller [1-NP]/[Pyr] ratio and larger [6-NBaP]/[BaP] ratio in Kitakyushu suggests that the major contributor of PAHs was not automobiles but iron manufacturing which uses a large amount of coal. The sudden increase in atmospheric PAH concentrations in the winter of 2014 may also be due to iron manufacturing.

Magnetite Nanoparticles Induce Genotoxicity in the Lungs of Mice via Inflammatory Response.

Nanomaterials are useful for their characteristic properties and are commonly used in various fields. Nanosized-magnetite (MGT) is widely utilized in medicinal and industrial fields, whereas their toxicological properties are not well documented. A safety assessment is thus urgently required for MGT, and genotoxicity is one of the most serious concerns. In the present study, we examined genotoxic effects of MGT using mice and revealed that DNA damage analyzed by a comet assay in the lungs of imprinting control region (ICR) mice intratracheally instilled with a single dose of 0.05 or 0.2 mg/animal of MGT was approximately two- to three-fold higher than that of vehicle-control animals. Furthermore, in gpt delta transgenic mice, gpt mutant frequency (MF) in the lungs of the group exposed to four consecutive doses of 0.2 mg MGT was significantly higher than in the control group. Mutation spectrum analysis showed that base substitutions were predominantly induced by MGT, among which G:C to A:T transition and G:C to T:A transversion were the most significant. To clarify the mechanism of mutation caused by MGT, we analyzed the formation of DNA adducts in the lungs of mice exposed to MGT. DNA was extracted from lungs of mice 3, 24, 72 and 168 h after intratracheal instillation of 0.2 mg/body of MGT, and digested enzymatically. 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and lipid peroxide-related DNA adducts were quantified by stable isotope dilution liquid chromatography-mass spectrometry (LC-MS/MS). Compared with vehicle control, these DNA adduct levels were significantly increased in the MGT-treated mice. In addition to oxidative stress- and inflammation related-DNA adduct formations, inflammatory cell infiltration and focal granulomatous formations were also observed in the lungs of MGT-treated mice. Based on these findings, it is suggested that inflammatory responses are probably involved in the genotoxicity induced by MGT in the lungs of mice.

Characteristics of the transformation frequency at the tumor promotion stage of airborne particulate and gaseous matter at ten sites in Japan.

We used a high-volume air sampler in the summer of 2007 and the winter of 2008 at ten Japanese sites (Sapporo, Sendai, Maebashi, Tsukuba, Shinjuku, Sagamihara, Shizuoka, Touhaku, Kitakyushu, and Kagoshima) to collect total suspended particulate (TSP) and gaseous matter for evaluation. We evaluated the transformation frequency at the tumor promotion stage of these samples in a cell transformation assay using Bhas 42 cells, which were established from BALB/c 3T3 cells transfected with the v-Ha-ras oncogene. All samples collected from the gaseous matter were negative for transformed foci. There were several patterns of transformation frequency at the tumor promotion stage by area for the TSP samples. At Sapporo, the transformation frequency at the tumor promotion stage was remarkably higher in winter than in summer as well as in winter at the other sites. At six urban cities from Sendai to Shizuoka, the levels of transformed frequencies per µg of suspended particulates in winter were almost the same, and were higher than those of the remaining three sites. At three sites, Touhaku, Kitakyushu and Kagoshima, the transformation results in winter were judged as negative. The characteristics of the transformed frequencies of the compounds adsorbed on particulate matter at the sampling sites were significant in winter. We also studied the correlation between the transformation frequency at the tumor promotion stage of the TSP samples and the results of quantitative analysis of 16 polyaromatic hydrocarbons (PAHs) at the ten sites. We found that the transformation frequency at the tumor promotion stage of airborne samples could not be predicted based on the quantitative results of the PAHs in those samples. These data suggest that direct risk assessment of air samples with a bioassay is more valuable than quantitative analysis of compounds such as PAHs for predicting carcinogenicity.

Genotoxicity of multi-walled carbon nanotubes in both in vitro and in vivo assay systems.

The genotoxic effects of multi-walled carbon nanotubes (MWCNTs) were examined by using in vitro and in vivo assays. MWCNTs significantly induced micronuclei in A549 cells and enhanced the frequency of sister chromatid exchange (SCE) in CHO AA8 cells. When ICR mice were intratracheally instilled with a single dose (0.05 or 0.2 mg/animal) of MWCNTs, DNA damage of the lungs, analysed by comet assay, increased in a dose-dependent manner. Moreover, DNA oxidative damage, indicated by 8-oxo-7,8-dihydro-2'-deoxyguanosine and heptanone etheno-deoxyribonucleosides, occurred in the lungs of MWCNT-exposed mice. The gpt mutation frequencies significantly increased in the lungs of MWCNT-treated gpt delta transgenic mice. Transversions were predominant, and G:C to C:G was clearly increased by MWCNTs. Moreover, many regions immunohistochemically stained for inducible NO synthase and nitrotyrosine were observed in the lungs of MWCNT-exposed mice. Overall, MWCNTs were shown to be genotoxic both in in vitro and in vivo tests; the mechanisms probably involve oxidative stress and inflammatory responses.

A pilot survey of 39 Victorian WWTP effluents using a high speed luminescent umu test in conjunction with a novel GC-MS-database technique for automatic identification of micropollutants.

In 2007, samples of treated effluent were collected at point of discharge to the environment from 39 wastewater treatment plants (WWTPs) located across Victoria, Australia grouped by treatment type. Sample genotoxicity was assessed with a high-throughput luminescent umu test method using Salmonella typhimurium TL210 strain, with and without addition of a commercially available metabolic activation system. Samples were also screened using a gas chromatographic-mass spectrometric mass-structure database recognition method. A genotoxic response was observed in half of the samples tested without metabolic activation system (

A pilot study of the water quality of the Yarra River, Victoria, Australia, using in vitro techniques.

A pilot study was initiated to provide the first information on the recombinant receptor-reporter gene bioassay (hormonal) activity of freshwaters in Victoria. The project involved the collection of water samples from six stations on the main stem of the Yarra River in and upstream of the city of Melbourne, Australia in April 2008 and April 2009. Samples were prepared for measurement of sample toxicity using a modified photobacterium test, genotoxicity using a high-throughput luminescent umu test method, and human and medaka estrogen receptor (hERα and medERα), retinoic acid receptor (RAR), aryl hydrocarbon receptor (AhR) and thyroid receptor (TR) assay activity using the relevant yeast-based bioassays. Most samples were only weakly or moderately toxic, with no relationship observed to location along the river. The data for 2008 suggests that at that time the Yarra River samples contained few compounds that were, in and of themselves, genotoxic. No estrogenic or thyroid, and <1 ng/L retinoic acid receptor activity was observed. AhR activity increased with progressed downstream. AhR activity was higher in April 2009 than at the same time in 2008, perhaps as a result of extensive bush fires in the catchment in the months immediately prior to sampling. About 24% of the total AhR activity observed was associated with suspended solids.

[Characteristics of indoor gaseous air pollutants in winter].

There are many gaseous air pollutants found in indoor air. It is very important to precisely measure the concentration of these compounds in order to evaluate the risk to human health and to reduce their concentrations. A diffusive sampling device is suitable for measurement of indoor air, because these are small, light, and can be used without a power supply for the pump. In this study, representative gaseous air pollutants in winter indoor and outdoor air were measured using diffusive sampling devices. Furthermore, the relationship between gaseous air pollutants, secondary formation mechanism, and the outbreak source were examined. The indoor concentrations of aldehydes, nitrogen dioxide and ammonia were higher than outdoor concentrations. By contrast, indoor concentrations of ozone were lower than outdoor concentrations. The indoor concentrations of nitrogen dioxide in 43% houses exceeded the maximum limit stated by environmental law (60 ppb). It was suggested that the main emission sources of nitrogen dioxide are kerosene and gas stoves. In addition, it was suggested that carbonyl compounds are formed by interactions between volatile organic compounds (VOCs) and ozone from outdoor air. Formic acid was estimated to be formed by the oxidation of formaldehyde with ozone, because a positive correlation between formaldehyde and formic acid, and an inverse correlation between formaldehyde and ozone, were observed in indoor air.

Apoptotic death of hematopoietic tumor cells through potentiated and sustained adhesion to fibronectin via VLA-4.

It has been postulated that inactivated beta1-integrins are involved in the disordered growth of hematopoietic tumor cells. We recently found that TNIIIA2, a peptide derived from tenascin-C, strongly activates beta1-integrins through binding with syndecan-4. We show here that Ramos Burkitt's lymphoma cells can survive and grow in suspension but undergo apoptosis when kept adhering to fibronectin by stimulation with TNIIIA2. Other integrin activators, Mg(2+) and TS2/16 (an integrin-activating antibody), were also capable of inducing apoptosis. The inactivation of ERK1/2 and Akt and the subsequent activation of Bad were involved in the apoptosis. The results using other hematopoietic tumor cell lines expressing different levels of fibronectin receptors (VLA-4 and VLA-5) showed that potentiated and sustained adhesion to fibronectin via VLA-4 causally induces apoptosis also in various types of hematopoietic tumor cells in addition to Ramos cells. Because TNIIIA2 requires syndecan-4 as a membrane receptor for activation of beta1-integrins, it induced apoptosis preferentially in hematopoietic tumor cells, which expressed both VLA-4 and syndecan-4 as membrane receptors mediating the effects of fibronectin and TNIIIA2, respectively. Therefore, normal peripheral blood cells, such as neutrophils, monocytes, and lymphocytes, which poorly expressed syndecan-4, were almost insusceptible to TNIIIA2-induced apoptosis. The TNIIIA2-related matricryptic site of TN-C could contribute, once exposed, to preventing prolonged survival of hematopoietic malignant progenitors through potentiated and sustained activation of VLA-4.

The expression of nerve growth factor in mice lung following low-level toluene exposure.

To clarify the effect of indoor air pollutants on nerve growth factor (NGF) production in lung, male C3H/HeN mice were exposed to filtered air (control) or toluene at levels of 0.9 ppm, 9 ppm, or 90 ppm for 30 min via nose-only inhalation on days 0, 1, 2, 7, 14, 21, 28, 35, 42, 49 and 56. As an allergic mouse model, some mice (n=24) were immunized with ovalbumin. Lungs from each mouse were collected to determine NGF and related receptor expressions using real-time reverse transcription polymerase chain reaction (RT-PCR) analysis. NGF and TrkA mRNAs were increased in the lungs of the immunized mice following exposure to 9 ppm toluene (n=6) (P<0.05 ppm vs. 0 ppm). Remarkably increased NGF-positive bronchiolus and alveolar epithelium cells were observed in 9 ppm toluene-exposed, immunized mice. To determine NGF mediating signaling, we also examined mRNA expression of neurotrophin receptor p75 (p75(NTR)) and oxidative stress marker, heme oxygenase (HO)-1 in the lung. There is no difference in the expressions of p75(NTR) and HO-1 between toluene-exposed and control mice. The expression of CCL2 and CCL3 mRNAs was significantly elevated in 9 ppm toluene-exposed, immunized mice. These findings suggest that the exposure with volatile organic compounds enhanced NGF expression and airway inflammation stronger in allergic individuals than in healthy individuals.

Running exercise for short duration increases bone mineral density of loaded long bones in young growing rats.

Running exercise is an effective therapy for the prevention of osteoporosis; however, appropriate duration of exercise has not been determined. We therefore investigated the effect of exercise duration on bone mineral density (BMD) and systemic bone metabolism using young growing rats. Fifteen 8-week-old female Wistar rats were divided into three groups according to running load: control group (no running), short duration (30 min/day) and long duration (180 min/day), and animals ran on a treadmill 5 days per week over an 8-week period. BMD of the tibia was measured using peripheral quantitative computed tomography, and serum levels of tartarate-resistant acid phosphatase (TRAP), a bone resorption marker and alkaline phosphatase (ALP), a bone formation marker were measured to know whether the treadmill exercise would affect systemic bone metabolism. Short-duration running exercise (30 min/day) caused a significant increase in BMD of the metaphyseal trabecula (p < 0.05) with a reduction of serum TRAP levels (p < 0.01) and an increase in serum levels of calcium (p < 0.05) and phosphorus (p < 0.01). Conversely, long-duration exercise (180 min/day) significantly reduced BMD of the diaphyseal and metaphyseal cortex and that of the diaphyseal trabecula with a significant reduction of serum ALP levels and a significant increase in serum phosphorus. These findings suggest that short-duration exercise may increase BMD through suppression of bone resorption, whereas long-duration exercise may reduce BMD through suppression of bone formation. Exercising for short duration but not prolonged exercise is recommended to increase BMD of loaded long bones.

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).

Behavior of cadmium and lead contained in wood during the carbonization process.

The behavior of heavy metals in wood during its carbonization process was examined. Cadmium in wood samples was found to be volatile when the samples were carbonized at 600 degrees C or higher, which demonstrated that removal of cadmium was feasible. Meanwhile, lead was found to be barely volatile even if the wood samples were carbonized at 1,000 degrees C or higher, which demonstrated that lead was difficult to remove and recover. The possibility of removing/recovering lead contained in wood by energization was then examined. By examining the concentration of sulfuric acid used as an electrolyte as well as load voltage, approximately 10% of lead was found to be recoverable.

Role of CD4(+) T cells in the modulation of neurotrophin production in mice exposed to low-level toluene.

To investigate the role of CD4(+) T cells in neurotrophin production following toluene exposure, male C3H mice were exposed to filtered air (control) or 9 ppm of toluene in a nose-only exposure chamber for 30 min on 3 consecutive days followed by weekly sessions for 4 weeks. All the mice were immunized with ovalbumin and some groups of mice were treated with anti-CD4 antibody. BDNF content in BAL fluid and NGF content in plasma were significantly increased in toluene-exposed mice. However, treatment with anti-CD4 mAb completely abrogated these effects. These findings suggest that the CD4(+) T cells may be involved in the toluene-induced modulation of neurotrophin production.

Comparison of carbonaceous aerosols in Tokyo before and after implementation of diesel exhaust restrictions.

We compared the status of carbonaceous aerosols in Tokyo before and after the implementation of a diesel vehicle regulation intended to reduce the quantity of particulate carbon from diesel engines in one of the largest scale ever attempts at vehicle exhaust control. Radiocarbon (14C) in elemental carbon (EC) and total carbon (TC) were analyzed to identify fossil fuel carbonaceous particles emitted from diesel-powered vehicles. One-sided paired-month t-tests showed no distinct difference in the absolute concentrations of particles in terms of total mass (19.5 to 18.0 microg m(-3); p = 0.321), EC (3.6 to 3.3 microg m(-3); p = 0.272), and TC (6.3 to 6.2 microg m(-3); p = 0.418) for the finest particles (d(a) < 1.1 microm) after the implementation of the regulation. The ratios of the concentrations of the chemical constituents were, however, altered after the regulation. EC/TC was significantly decreased from 56.7% to 50.2% (p = 0.039). Although it was not statistically significant, the percentage of fossil carbon in EC also decreased (67.8% to 63.8%; p = 0.104). Since EC is predominantly of combustion origin, the observed decrease was likely due to the decrease in fossil EC emissions from diesel-powered vehicles. The decrease in EC/TC after the implementation of the regulation was also likely to have resulted from attachment to diesel vehicle exhaust systems of particulate filters as required as part of the regulation by the Tokyo Metropolitan Government. The EC/TC of fossil carbon of the finest particles decreased from 66.2% to 55.2% (p = 0.066), but EC/TC of biomass carbon did not decrease but rose slightly from 43.6% to 44.5% (p > 0.5). Thus, the relative ratios of components of carbonaceous aerosol particles, such as 14C, could provide a better understanding of the atmospheric pollution status, despite short-term fluctuations, than do measurements of absolute concentrations.

Athymic nude mice are insensitive to low-level toluene-induced up-regulation of memory-related gene expressions in the hippocampus.

The function of the N-methyl-d-aspartate (NMDA) subtype of glutamatergic receptors is known to be antagonized by toluene, a well-characterized neurotoxic chemical known to impair memory functions. Recently, peripheral T cells have been clearly shown to play an important role in cognitive and behavioral functions. In the present study, we investigated the role of peripheral T cells in the hippocampal mRNA expression of memory-related genes induced by low levels of toluene exposure in mice. BALB/c wild-type (WT) and nude mice were exposed to 9ppm of toluene or filtered air (0ppm toluene; control groups) in a nose-only exposure chamber for 30min on 3 consecutive days followed by weekly sessions for 4 weeks. Twenty-four hours after the last exposure, the hippocampi were collected and the inducibility of memory-related genes was examined using a real-time quantitative PCR method. NMDA NR2A, calcium/calmodulin-dependent protein kinase IV (CaMKIV), cyclic AMP-responsive element binding protein 1 (CREB1), and BDNF were significantly up-regulated in the hippocampi of WT mice exposed to 9ppm of toluene, compared to the expressions observed in WT mice exposed to filtered air, but similar results were not observed in nude mice. To investigate the possible involvement of peripheral T cells in the toluene-induced up-regulation of memory-related genes in WT mice, we examined the mRNA expression of Thy-1 (a pan T cell-specific marker) and quantified the number of cells that were immunoreactive to a T cell antigen receptor, CD3 (CD3-ir). Both the expression of Thy-1 mRNA and the number of CD3-ir cells were significantly higher in the hippocampi of the WT mice exposed to 9ppm of toluene, compared with that in WT mice exposed to filtered air; similar results were not observed in nude mice. We also examined the expression of chemokine genes like CCL2 and CCL3. The expression of CCL3 mRNA was significantly up-regulated only in the toluene-exposed WT mice. Although other differences unrelated to immune function may exist between WT and nude mice from the same background, the findings of the present study strongly suggest that the recruitment of peripheral T cells in the hippocampi of BALB/c WT mice exposed to low levels of toluene may be involved in the toluene-induced up-regulation of memory-related genes at the mRNA level.

Modulation of neurological related allergic reaction in mice exposed to low-level toluene.

The contributing role of indoor air pollution to the development of allergic disease has become increasingly evident in public health problems. It has been reported that extensive communication exists between neurons and immune cells, and neurotrophins are molecules potentially responsible for regulating and controlling this neuroimmune crosstalk. The adverse effects of volatile organic compounds which are main indoor pollutants on induction or augmentation of neuroimmune interaction have not been fully characterized yet. To investigate the effects of low-level toluene inhalation on the airway inflammatory responses, male C3H mice were exposed to filtered air (control), 9 ppm, and 90 ppm toluene for 30 min by nose-only inhalation on Days 0, 1, 2, 7, 14, 21, and 28. Some groups of mice were injected with ovalbumin intraperitoneally before starting exposure schedule and these mice were then challenged with aerosolized ovalbumin as booster dose. For analysis of airway inflammation, bronchoalveolar lavage (BAL) fluid were collected to determine inflammatory cell influx and lung tissue and blood samples were collected to determine cytokine and neurotrophin mRNA and protein expressions and plasma antibody titers using real-time RT-PCR and ELISA methods respectively. Exposure of the ovalbumin-immunized mice to low-level toluene resulted in (1) increased inflammatory cells infiltration in BAL fluid; (2) increased IL-5 mRNA, decreased nerve growth factor receptor tropomyosin-related kinase A and brain-derived neurotrophic factor mRNAs in lung; and (3) increased IgE and IgG(1) antibodies and nerve growth factor content in the plasma. These findings suggest that low-level toluene exposure aggravates the airway inflammatory responses in ovalbumin-immunized mice by modulating neuroimmune crosstalk.

Detection of aminophenylnorharman, a possible endogenous mutagenic and carcinogenic compound, in human urine samples.

Mutagenic/carcinogenic 9-(4'-aminophenyl)-9H-pyrido[3,4-b]indole [aminophenylnorharman (APNH)] is formed from norharman and aniline in the presence of cytochrome P450 3A4/1A2. Because both precursors are widely distributed in the environment, human exposure is unavoidable. To clarify APNH formation in the human body, amounts of the compound in 24-h human urine collected from smokers and nonsmokers, eating a normal diet, were analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry. In addition, norharman and aniline were also analyzed by high-performance liquid chromatography and gas chromatography, respectively. APNH could be detected in all urine samples at levels 49 to 449 pg for smokers and 21 to 594 pg for nonsmokers per 24-h urine, respectively. The amounts of norharman and aniline were 46 to 185 ng and 0.70 to 8.10 microg for smokers and 52 to 447 ng and 0.49 to 5.72 microg for nonsmokers, respectively, per 24-h urine (none of the levels differing significantly between smokers and nonsmokers). To exclude exogenous exposure to norharman and aniline, we analyzed the levels of APNH, norharman, and aniline in urine samples collected from inpatients receiving parenteral alimentation. Similar to the healthy volunteers, all urine samples contained 12 to 338 pg of APNH, 6 to 75 ng of norharman, and 0.33 to 1.86 microg of aniline per 24-h urine. These results suggest that APNH should be considered as a novel endogenous mutagen/carcinogen; thus, it is very important to determine the biological significance of this carcinogen for human cancer development.

Activity related to the carcinogenicity of plastic additives in the benzophenone group.

This study examines the activities relating to the carcinogenicity of six types of benzophenone derivatives (benzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone) currently used in plastic products as additives to serve as ultraviolet absorbing agents. The evaluation of the initiation activity used a light absorption umu-test, a luminescent umu-test and the Ames test. The promotion activity was examined by a Bhas assay, a method that uses Bhas 42 cells for the formation of transformation foci. The luminescent umu-test indicated positive initiation activity of 2-hydroxy-4-methoxybenzophenone, and pseudo-positive activity of 2,4-dihydroxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone. In the Ames test, 2-hydroxy-4-octyloxybenzophenone showed pseudo-positive initiation activity. Conversely, 2,4-dihydroxybenzophenone indicated weak promotion activity at 10 microg/ml concentration.

Measurements of exposure concentrations of benzene, toluene and xylene, and amounts of respiratory uptake.

With respect to benzene, toluene, and o-, m- and p-xylene contained in indoor air, this study determined the amounts of their uptake through the human respiratory system using the difference between concentrations in inhalation and exhalation, and examined their relationship to concentrations in blood and urine measured before and after exposure. At relatively high concentrations, respiratory absorption of these compounds tended to increase rapidly in the early stage of exposure but decrease after several hours. It was also confirmed that concentrations of these compounds in both blood and urine increased during the first 3 hours of exposure. These results suggested that measurements of concentrations in inhalation and exhalation may provide a simple method for estimating the extent of respiratory exposure to these substances.