Effects of motorcycle exhaust inhalation exposure on cytochrome P-450 2B1, antioxidant enzymes, and lipid peroxidation in rat liver and lung

The contribution of moped emissions to ultrafine and fine particle concentrations on bike lanes

Although not emitting air pollution themselves, cyclists are exposed to air pollution from motorised traffic. Because of the close proximity of mopeds to cyclists, moped emissions may affect cyclist exposure. However, the quantitative contribution of mopeds to cyclists' air pollution exposures is uncertain. The aim of the research was to quantify the contribution of moped emissions to air pollution concentrations on bike lanes. Measurements of Particle Number Concentrations (PNC),¹ Particulate Matter (PM)² and Black Carbon (BC)³ on bike lanes were performed in September 2016 in four Dutch cities. Passing two- and four-stroke mopeds and other traffic were recorded and distinguished by sound by the trained field worker. One-second PNC, PM and one-minute BC concentrations were measured. Using regression analyses the contribution of passing mopeds to air pollution exposure was analysed. At 18 non-tunnel locations, two-stroke and four-stroke mopeds contributed at average 12,000 and 3000 pt./cm³ PNC per second when passing by, respectively. In a tunnel, this was 92,000 and 12,000 pt./cm³. Two- and four-strokes added 3 to 19% to total PNC at non-tunnel sites and 58% in a tunnel. Four-strokes caused at average 54% of the contribution of moped emissions to total PNC. At non-tunnel sites, the contribution of mopeds to PM was 1.2 and 0.2 μg/m³ for two- and four-strokes, respectively. In a tunnel this was 3.9 and 2.3 μg/m³. Minute-measurements of BC did not show a relation between mopeds passing by and BC. Mopeds caused substantial short-term increases in air pollution levels on bike lanes, especially in a tunnel. Two-stroke mopeds caused higher concentration peaks than four-stroke mopeds. The contribution to total air pollution concentrations of four-stroke mopeds was larger, because of the higher share of four-strokes. Because of the close proximity of mopeds to cyclists, cyclists air pollution exposure can be largely influenced by moped emissions.

Air pollution and effects on reproductive-system functions globally with particular emphasis on the Brazilian population

In recent years, numerous studies showed that exposure to environmental air pollutants affected reproductive functions and, in particular, produced adverse effects on pregnancy outcomes, fertility, and fetal health. Epidemiological studies demonstrated that exposure to ambient levels of air pollutants are associated with low birth weight, intrauterine growth retardation, prematurity, neonatal death, and decreased fertility in males. Experimental animal data supported these findings and indicated that female fertility was also disturbed. Although there are various mechanisms of action suggested to show the manner in which air pollutants alter pregnancy and the reproductive systems in both genders, further studies are needed to correlate causal relationships. This information would serve to better understand the underlying physiologic changes in the reproductive system induced by exposure to air pollutants and possibly establish a link between the dose and response of individual or mixture of air pollutants.

Motorcycle exhaust induces reproductive toxicity and testicular interleukin-6 in male rats

Motorcycle exhaust (ME) from two-stroke engines contains many toxicants and poses a potential health hazard. The major objectives of the present study were to investigate the male reproductive toxicity of ME and the underlying mechanisms of toxicity. Male Wistar rats were exposed to ME by inhalation 1 h each in the morning and afternoon, Monday through Friday. Exposures to 1:50 diluted ME for 4 weeks or to 1:10 diluted ME for 2 and 4 weeks showed concentration- and time-dependent decreases of testicular weight, spermatid number, and cauda epididymal sperm number. Subsequent studies were done using 4-week exposure to 1:10 diluted ME. ME caused histopathological changes including testicular spermatocytic necrosis and seminiferous tubule atrophy and cauda epididymal formation of clusters of pyknotic and necrotic sperm cells. ME-exposed male rats mated with untreated females showed decreases of male mating index and female fertility index and an increase of implantation site loss. ME decreased 7-ethoxycoumarin O-deethylase and superoxide dismutase activities but induced proinflammatory cytokine interleukin-6 (IL-6) messenger RNA (mRNA) in the testis. Male rats were exposed to ME with or without cotreatment with 50 mg/kg vitamin E orally for 4 weeks. ME decreased serum testosterone concentration. This effect was reversed by cotreatment with vitamin E. ME decreased testicular spermatid number and induced IL-6 mRNA and protein. These effects were also reversed by the vitamin E cotreatment. The present findings show that ME causes male reproductive effects and induces testicular IL-6 in rats by mechanisms involving induction of oxidative stress and inhibition of steroidogenesis.

Compositions and oxidative damage of condensate, particulate and semivolatile organic compounds from gasoline exhausts

The effects of extracts of condensate, particulate and semivolatile organic compounds from absolute gasoline exhausts on DNA single strand break, levels of malondialdehyde (MDA), carbonyl protein and activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were investigated in lungs and brains of adult Sprague-Dawley rats of both sexes. In addition, the non-conventional components of the extracts and concentrations of 13 polycyclic aromatic hydrocarbon (PAHs) in gasoline exhaust were measured by GS/MS. Extract of gasoline exhaust at different doses (5.6, 16.7 and 50.0L/kg) were given to administered animals by intratracheal instillation once a week for 4 weeks, while blank control and solvent groups were given with physiological saline and dimethyl sulfoxide (DMSO). Our results showed that gasoline exhaust increased DNA single strand break, promoted lipid peroxidation and oxidative protein damage and decreased activities of SOD in lungs and brains. While, it decreased the activities of GPx in lungs but not in brains. The present data suggested that gasoline exhaust exposure could cause oxidative damage to lung and brain of rats. That was to say that gasoline is a toxin to brain of mammals, not only to lung.

Induction of fibroblast growth factor-9 and interleukin-1alpha gene expression by motorcycle exhaust particulate extracts and benzo(a)pyrene in human lung adenocarcinoma cells

Motorcycle exhaust particulates (MEP) contain carcinogenic polycyclic aromatic hydrocarbons including benzo(a)pyrene. This study has determined the ability of MEP to alter the expression of select genes from drug metabolism, cytokine, oncogene, tumor suppressor, and estrogen signaling families of human lung adenocarcinoma CL5 cells. cDNA microarray analyses and confirmation studies were performed using CL5 cells treated with 100 microg/ml MEP extract for 6 h. The results showed that MEP increased the mRNA levels of metabolic enzymes CYP1A1 and CYP1B1, proinflammatory cytokines interleukin (IL)-1alpha, IL-6, and IL-11, fibroblast growth factor (FGF)-6 and FGF-9, vascular endothelial growth factor (VEGF)-D, oncogene fra-1, and tumor suppressor p21. In contrast, MEP decreased tumor suppressor Rb mRNA in CL5 lung epithelial cells. Treatment with 10 microM benzo(a)pyrene for 6 h altered gene expression profiles, in a manner similar to those by MEP. Induction of IL-1alpha, IL-6, IL-11, and FGF-9 mRNA by MEP and benzo(a)pyrene was concentration and time dependent. Cotreatment with 2 mM N-acetylcysteine blocked the MEP- and benzo(a)pyrene-mediated induction. Treatment with MEP or benzo(a)pyrene increased IL-6 and IL-11 releases to CL5 cell medium. Incubation of human lung fibroblast WI-38 with MEP- or benzo(a)pyrene-induced CL5 conditioned medium for 4 days stimulated cell growth of the fibroblasts. Inhalation exposure of rats to 1:10 diluted motorcycle exhaust 2 h daily for 4 weeks increased CYP1A1, FGF-9, and IL-1alpha mRNA in lung. This present study shows that MEP and benzo(a)pyrene can induce metabolic enzyme, inflammatory cytokine, and growth factor gene expression in CL5 cells and stimulate lung epithelium-fibroblast interaction.