Kinetics of silica nanoparticles in the human placenta.

The potential medical applications of nanoparticles (NPs) warrant their investigation in terms of biodistribution and safety during pregnancy. The transport of silica NPs across the placenta was investigated using two models of maternal-foetal transfer in human placenta, namely, the BeWo b30 choriocarcinoma cell line and the ex vivo perfused human placenta. Nanotoxicity in BeWo cells was examined by the MTT assay which demonstrated decreased cell viability at concentrations >100 µg/mL. In the placental perfusion experiments, antipyrine crossed the placenta rapidly, with a foetal:maternal ratio of 0.97 ± 0.10 after 2 h. In contrast, the percentage of silica NPs reaching the foetal perfusate after 6 h was limited to 4.2 ± 4.9% and 4.6 ± 2.4% for 25 and 50 nm NPs, respectively. The transport of silica NPs across the BeWo cells was also limited, with an apparent permeability of only 1.54 × 10(-6) ± 1.56 × 10(-6) cm/s. Using confocal microscopy, there was visual confirmation of particle accumulation in both BeWo cells and in perfused placental tissue. Despite the low transfer of silica NPs to the foetal compartment, questions regarding biocompatibility could limit the application of unmodified silica NPs in biomedical imaging or therapy.

The human placenta--an alternative for studying foetal exposure.

Pregnant women are daily exposed to a wide selection of foreign substances. Sources are as different as lifestyle factors (smoking, daily care products, alcohol consumption, etc.), maternal medication or occupational/environmental exposures. The placenta provides the link between mother and foetus, and though its main task is to act as a barrier and transport nutrients and oxygen to the foetus, many foreign compounds are transported across the placenta to some degree and may therefore influence the unborn child. Foetal exposures to environmental and medicinal products may have impact on the growth of the foetus (e.g. cigarette smoke) and development of the foetal organs (e.g. methylmercury and thalidomide). The scope of this review is to give insight to the placental anatomy, development and function. Furthermore, the compounds physical properties and the transfer mechanism across the placental barrier are evaluated. In order to determine the actual foetal risk from exposure to a chemical many studies regarding the topic are necessary, including means of transportation, toxicological targets and effects. For this purpose several in vivo and in vitro models including the placental perfusion system are models of choice.

Urinary 1-hydroxypyrene in children living in city and rural residences in Denmark.

AIMS: The present study aims to assess the biological uptake in children of polycyclic aromatic hydrocarbons measured as 1-hydroxypyrene in urine from children living in city and rural residences. METHODS: 103 children living in Copenhagen and 101 children living in rural residences of Denmark collected urine samples Monday to Friday morning. Each day, the family filled in a printed diary that included questions about the time and activity patterns of the child. Multiple regression analyses were used to identify predictors of the excreted 1-hydroxypyrene level. RESULTS: During the week, the children excreted on average 0.07 [95% CI: 0.01-0.41] micromol urinary 1-hydroxypyrene per mol creatinine. Children living in urban residences excreted 0.02 [95% CI: 0.01-0.05] micromol more 1-hydroxypyrene than children living in rural residences. This was confirmed in the multiple regression analysis showing a 29% (95% CI: 2-64%) higher excretion among urban children than rural children. Moreover, the regression analysis showed that for each hour per day spent outside the children excreted 58% (1.58 [1.22-2.03]) more 1-hydroxypyrene in urine. CONCLUSION: The present study indicates that children living in urban residences are more exposed to PAH than children living in rural residences. Time spent outdoors increased the excretion of 1-hydroxypyrene, which was most evident among urban children. Higher concentrations of ambient air pollution in urban areas may explain this finding. No influence of environmental tobacco smoke, cooking habits, and heating facilities was detected.

Cytogenetic effects in children and mothers exposed to air pollution assessed by the frequency of micronuclei and fluorescence in situ hybridization (FISH): a family pilot study in the Czech Republic.

A family pilot study was conducted in the Czech Republic to test the hypothesis that exposure to air pollution with particulate matter (PM) in children results in detectable effects indicated by a number of biomarkers of exposure and early effects. The frequency of micronuclei (MN) in peripheral blood lymphocytes (PBLs) was analysed to assess the cytogenetic effects in children and mothers living in two different areas. From each area two groups of children from a total of 24 families (mean age: 6.0+/-0.6 and 9.0+/-1.2 years) in a total of 47 children and 19 mothers (mean age: 33.6+/-3.9 years) participated. Chromosome aberrations determined with fluorescence in situ hybridization (FISH) painting for chromosomes #1 and #4 were analysed in 39 children and 20 parents. Teplice, a mining district, in Northern Bohemia was selected for the analyses of the effects in a population exposed to high levels of air pollution, especially during winter, and compared with a population from the rural area of Prachatice in Southern Bohemia. Significant higher frequencies of MN were found in the younger children living in the Teplice area as compared with those living in the Prachatice area (7.0+/-2.3 per thousand versus 4.9+/-2.0 per thousand, p=0.04). Higher levels of MN were also measured in the older children and the mothers from the Teplice area (9.2+/-3.7 per thousand versus 6.6+/-4.4 per thousand) and (12.6+/-3.4 per thousand versus 10.1+/-4.0 per thousand). The increased MN frequency may be associated with elevated carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) concentration of the PM(2.5) measured in the ambient Teplice air, but other factors like genotoxic compounds from the diet or protective effect of micronutrients, which was not addressed in this pilot study, may also differ between the two areas. MN frequencies were found to increase with age in children. Lower MN frequency was found in boys as compared to girls. The result of the FISH analyses showed a low number of individuals with detectable levels of aberrations and no significant increases in genomic frequency of stable chromosome exchanges (F(G)/100) were found in children or parents from the Teplice area in comparison with those from the Prachatice area. The family pilot study indicates that MN is a valuable and sensitive biomarker for early biological effect in children and adults living in two different areas characterised with significant exposure differences in c-PAHs concentrations during winter.

Urinary 1-hydroxypyrene in children living in city and rural residences in Denmark.

AIMS: The present study aims to assess the biological uptake in children of polycyclic aromatic hydrocarbons measured as 1-hydroxypyrene in urine from children living in city and rural residences. METHODS: 103 children living in Copenhagen and 101 children living in rural residences of Denmark collected urine samples Monday to Friday morning. Each day, the family filled in a printed diary that included questions about the time and activity patterns of the child. Multiple regression analyses were used to identify predictors of the excreted 1-hydroxypyrene level. RESULTS: During the week, the children excreted on average 0.07 [95% CI: 0.01-0.41] mumol urinary 1-hydroxypyrene per mol creatinine. Children living in urban residences excreted 0.02 [95% CI: 0.01-0.05] mumol more 1-hydroxypyrene than children living in rural residences. This was confirmed in the multiple regression analysis showing a 29% (95% CI: 2-64%) higher excretion among urban children than rural children. Moreover, the regression analysis showed that for each hour per day spent outside the children excreted 58% (1.58 [1.22-2.03]) more 1-hydroxypyrene in urine. CONCLUSION: The present study indicates that children living in urban residences are more exposed to PAH than children living in rural residences. Time spent outdoors increased the excretion of 1-hydroxypyrene, which was most evident among urban children. Higher concentrations of ambient air pollution in urban areas may explain this finding. No influence of environmental tobacco smoke, cooking habits, and heating facilities was detected.

Impact of types of lymphocyte chromosomal aberrations on human cancer risk: results from Nordic and Italian cohorts.

The frequency of cells with structural chromosomal aberrations (CAs) in peripheral blood lymphocytes is the first genotoxicity biomarker that has shown an association with cancer risk. CAs are usually divided into chromosome-type (CSAs) and chromatid-type aberrations (CTAs), with different mechanisms of formation. From a mechanistic point of view, it is of interest to clarify whether the cancer predictivity of CAs is different with respect to CSAs and CTAs. We report here cancer risk for cytogenetically tested, healthy subjects with respect to frequency of CAs, CSAs, and CTAs in peripheral blood lymphocytes, using Nordic (1981 subjects with CA data, 1871 subjects with CSA/CTA data) and Italian (1573 subjects with CA data, 877 subjects with CTA/CSA data) cohorts, with a median follow-up of 17 years. High levels of CAs at test were clearly associated with increased total cancer incidence in the Nordic cohorts and increased total cancer mortality in the Italian cohort. In the Nordic cohorts, significantly elevated cancer risks were observed for subjects with both high CSAs and high CTAs at test, and these variables showed equally strong cancer predictivity. The results of the Italian cohort did not indicate any clear-cut difference in cancer predictivity between the CSA and CTA biomarkers. There was no significant effect modification by age at test, gender, country, or time since test. The results suggest that both DNA double-strand breaks and other initial DNA lesions responsible for CSAs and CTAs are associated with cancer risk.

Urinary 1-hydroxypyrene and mutagenicity in bus drivers and mail carriers exposed to urban air pollution in Denmark.

BACKGROUND: Previous studies in Denmark have shown that bus drivers and tramway employees were at an increased risk for developing several types of cancer and that bus drives from central Copenhagen have high levels of biomarkers of DNA damage. AIMS: The present study evaluates 1-hydroxypyrene concentrations and mutagenic activity in urine as biomarkers of exposure in non-smoking bus drivers in city and rural areas on a work day and a day off and in non-smoking mail carriers working outdoors (in the streets) and indoors (in the office). METHODS: Twenty-four hour urine samples were collected on a working day and a day off from 60 non-smoking bus drivers in city and rural areas and from 88 non-smoking mail carriers working outdoors (in the streets) and indoors (in the office). The concentration of 1-hydroxypyrene was measured by means of HPLC and the mutagenic activity was assessed by the Ames assay with Salmonella tester strain YG1021 and S9 mix. The N-acetyltransferase (NAT2) phenotype was used as a biomarker for susceptibility to mutagenic/carcinogenic compounds. RESULTS: Bus drivers excreted more 1-hydroxypyrene in urine than did mail carriers. The differences were slightly smaller when NAT2 phenotype, cooking at home, exposure to vehicle exhaust, and performing physical exercise after work were included. The NAT2 slow acetylators had 29% (1.29 [CI: 1.15-1.98]) higher 1-hydroxypyrene concentrations in urine than the fast acetylators. Male bus drivers had 0.92 revertants/mol creatinine [CI: 0.37-1.47] and female bus drivers 1.90 revertants/mol creatinine [CI: 1.01-2.79] higher mutagenic activity in urine than mail carriers. CONCLUSION: The present study indicates that bus drivers are more exposed to polycyclic aromatic hydrocarbons (PAH) and mutagens than mail carriers. Mail carriers who worked outdoors had higher urinary concentration of 1-hydroxypyrene, a marker of exposure to PAH, than those working indoors. The individual levels of urinary mutagenic activity were not correlated to excretion of 1-hydroxypyrene. This might be due to the fact that the most potent mutagenic compounds in diesel exhaust are not PAH but dinitro-pyrenes. Among bus drivers, fast NAT2 acetylators had higher mutagenic activity in urine than slow NAT2 acetylators and female bus drivers had higher mutagenic activity than male bus drivers.

[Follow-up examination of Danish stainless steel welders previously examined in 1987]. / Opfølgende undersøgelse af danske rustfrit stål-svejsere, tidligere undersøgt i 1987.

INTRODUCTION: A Danish cohort from 1987 consisting of 226 stainless steel welders and reference persons is part of the European Study Group on Cytogenetic Biomarkers and Health (ESCH). In ESCH increased cancer morbidity and mortality was significantly associated with high levels of chromosomal aberrations, measured in blood samples several years prior to cancer registration. The positive association was found in two cohorts from the Nordic countries and from Italy. MATERIAL AND METHODS: ESCH followed all registered cancer cases and control persons by questionnaires and interviews to obtain information about exposures in the period from the time of blood sampling for chromosomal aberration analysis to the time of cancer diagnosis. In Denmark the total cohort was included in the inquiry and the ESCH questions were supplemented with questions from the Danish National Work Environment Cohort Study 1990-95. RESULTS: Responses from one hundred and forty-four persons showed that seventy-four were employed at the same workplace place as in 1987. Differences in occupational exposures, such as more noise, heat and insufficient lighting and no differences in the self-rated health were found in comparison with the Danish National Work Environment Cohort Study as such and with the sample of metal workers. Only very few of the study persons knew the threshold limit value of welding fumes but a majority found that the working environment had improved during the past ten years. DISCUSSION: This study confirms hazardous exposures in stainless steel welding. The threshold limit value, however, has been lowered since 1987 suggesting there is less cancer risk today from stainless steel welding.