From in utero and childhood exposure to parental smoking to childhood cancer: a possible link and the need for action

Observational methods for human studies of transgenerational effects

There are substantial challenges in studying human transgenerational epigenetic outcomes resulting from environmental conditions. The task requires specialized methods and tools that incorporate specific knowledge of multigenerational relationship combinations of probands and their ancestors, phenotype data for individuals, environmental information of ancestors and their descendants, which can span historical to present datasets, and informative environmental data that chronologically aligns with ancestors and descendants over space and time. As a result, there are few epidemiologic studies of potential transgenerational effects in human populations, thus limiting the knowledge of ancestral environmental conditions and the potential impacts we face with modern human health outcomes. In an effort to overcome some of the challenges in studying human transgenerational effects, we present two transgenerational study designs: transgenerational space-time cluster detection and transgenerational case-control study design. Like other epidemiological methods, these methods determine whether there are statistical associations between phenotypic outcomes (e.g., adverse health outcomes) among probands and the shared environments and environmental factors facing their ancestors. When the ancestor is a paternal grandparent, a statistically significant association provides some evidence that a transgenerational inheritable factor may be involved. Such results may generate useful hypotheses that can be explored using epigenomic data to establish conclusive evidence of transgenerational heritable effects. Both methods are proband-centric: They are designed around the phenotype of interest in the proband generation for case selection and family pedigree creation. In the examples provided, we incorporate at least three generations of paternal lineage in both methods to observe a potential transgenerational effect.

Thirdhand tobacco smoke exposure increases the genetic background-dependent risk of pan-tumor development in Collaborative Cross mice

Increasing evidence has shown that thirdhand smoke (THS) exposure is likely to induce adverse health effects. An important knowledge gap remains in our understanding of THS exposure related to cancer risk in the human population. Population-based animal models are useful and powerful in investigating the interplay between host genetics and THS exposure on cancer risk. Here, we used the Collaborative Cross (CC) mouse population-based model system, which recapitulates the genetic and phenotypic diversity observed in the human population, to assess cancer risk after a short period of exposure, between 4 and 9 weeks of age. Eight CC strains (CC001, CC019, CC026, CC036, CC037, CC041, CC042 and CC051) were included in our study. We quantified pan-tumor incidence, tumor burden per mouse, organ tumor spectrum and tumor-free survival until 18 months of age. At the population level, we observed a significantly increased pan-tumor incidence and tumor burden per mouse in THS-treated mice as compared to the control (p = 3.04E-06). Lung and liver tissues exhibited the largest risk of undergoing tumorigenesis after THS exposure. Tumor-free survival was significantly reduced in THS-treated mice compared to control (p = 0.044). At the individual strain level, we observed a large variation in tumor incidence across the 8 CC strains. CC036 and CC041 exhibited a significant increase in pan-tumor incidence (p = 0.0084 and p = 0.000066, respectively) after THS exposure compared to control. We conclude that early-life THS exposure increases tumor development in CC mice and that host genetic background plays an important role in individual susceptibility to THS-induced tumorigenesis. Genetic background is an important factor that should be taken into account when determining human cancer risk of THS exposure.

Neurological repercussions of neonatal nicotine exposure: A review

Smoking during pregnancy is hazardous to both the mother and the foetus, according to a substantial amount of recorded data. Exposure to nicotine and other compounds in cigarette smoke increases the risk of sudden infant death syndrome (SIDS) by two to five times during pregnancy. Serotonergic abnormalities have been discovered in SIDS infants in the zone of the medulla oblongata, which is known to control cardio-respiratory function. SIDS establishes a connection between depression, learning difficulties and behavioural disorders. Prenatal nicotine intake during the second trimester affects the dopaminergic neurological system, making the foetal brain more susceptible to nicotine and developing ADHD symptoms not just in a foetus but in adolescents also. Prenatal nicotine exposure alters the neurological route of neurotransmitters, acetylcholine and dopamine. Nicotine enhances neuronal activity in adults but desensitizes these processes in babies and young children exposed prenatally. The impact of a neurotoxin like nicotine is determined by the amount and duration of exposure. Continued exposure throughout pregnancy will influence a wide range of activities in the neurodevelopment, whereas exposure confined to a single stage of pregnancy may only affect the processes that are forming at that stage. To decrease the effect of nicotine on neonates due to maternal smoking strategies like nicotine replacement therapy (NRT), folic acid treatment and other behavioural treatments have been studied. Hence, this review focuses on the impact of exposure to nicotine on neonates, which results in various neurological consequences and smoking cessation therapies.

Urine 4-(methylnitrosamino)-1-(3) pyridyl-1-butanol and cotinine in Alaska native postpartum women and neonates comparing smokers and smokeless tobacco users

OBJECTIVE

Foetuses and neonates of women who use tobacco are exposed to nicotine and tobacco-derived carcinogens. We determined the relationship between urine biomarkers of tobacco toxicant exposure postpartum and in the neonates of Alaska Native (AN) women, comparing smokers and smokeless tobacco (ST) users, including iqmik, a homemade ST product.

METHODS

AN women, including 36 smokers, 9 commercial ST and 16 iqmik users their neonates participated. Urine from the woman at the time of delivery and her neonate's first urine were analysed for cotinine, the major metabolite of nicotine, and 4-(methylnitrosamino)-1-(3) pyridyl-1-butanol (NNAL), a tobacco-specific carcinogen biomarker.

RESULTS

Maternal urine cotinine and neonatal urine cotinine were strongly correlated in all tobacco use groups (r from 0.83 to 0.9, p < 0.002). Correlations between maternal cotinine and neonatal NNAL were moderately strong for cigarettes and commercial smokeless but weaker for iqmik users (r 0.73, 0.6 and 0.36, respectively).

CONCLUSION

Correlations between maternal and neonatal biomarkers of tobacco toxicant exposure vary, dependent on tobacco product use.

SIGNIFICANCE

This study provides novel data on biomarkers of tobacco exposure among postpartum AN women and their neonates. The results could be useful to guide future epidemiological studies of health risks associated with use of various tobacco products during pregnancy.

Maternal smoking impacts key biological pathways in newborns through epigenetic modification in Utero

BACKGROUND

Children exposed to maternal smoking during pregnancy exhibit increased risk for many adverse health effects. Maternal smoking influences methylation in newborns at specific CpG sites (CpGs). Here, we extend evaluation of individual CpGs to gene-level and pathway-level analyses among 1062 participants in the Norwegian Mother and Child Cohort Study (MoBa) using the Illumina 450 K platform to measure methylation in newborn DNA and maternal smoking in pregnancy, assessed using the biomarker, plasma cotinine. We used novel implementations of bioinformatics tools to collapse epigenome-wide methylation data into gene- and pathway-level effects to test whether exposure to maternal smoking in utero differentially methylated CpGs in genes enriched in biologic pathways. Unlike most pathway analysis applications, our approach allows replication in an independent cohort.

RESULTS

Data on 485,577 CpGs, mapping to a total of 20,199 genes, were used to create gene scores that were tested for association with maternal plasma cotinine levels using Sequence Kernel Association Test (SKAT), and 15 genes were found to be associated (q < 0.25). Six of these 15 genes (GFI1, MYO1G, CYP1A1, RUNX1, LCTL, and AHRR) contained individual CpGs that were differentially methylated with regards to cotinine levels (p < 1.06 × 10-7). Nine of the 15 genes (FCRLA, MIR641, SLC25A24, TRAK1, C1orf180, ITLN2, GLIS1, LRFN1, and MIR451) were associated with cotinine at the gene-level (q < 0.25) but had no genome-wide significant individual CpGs (p > 1.06 × 10-7). Pathway analyses using gene scores resulted in 51 significantly associated pathways, which we tested for replication in an independent cohort (q < 0.05). Of those 32 replicated in an independent cohort, which clustered into six groups. The largest cluster consisted of pathways related to cancer, cell cycle, ERα receptor signaling, and angiogenesis. The second cluster, organized into five smaller pathway groups, related to immune system function, such as T-cell regulation and other white blood cell related pathways.

CONCLUSIONS

Here we use novel implementations of bioinformatics tools to determine biological pathways impacted through epigenetic changes in utero by maternal smoking in 1062 participants in the MoBa, and successfully replicate these findings in an independent cohort. The results provide new insight into biological mechanisms that may contribute to adverse health effects from exposure to tobacco smoke in utero.

Parental smoking during pregnancy shortens offspring's legs

One of the most severe detrimental environmental factors acting during pregnancy is foetal smoke exposure. The aim of this study was to assess the effect of maternal, paternal and parental smoking during pregnancy on relative leg length in 7- to 10-year-old children. The research conducted in the years 2001-2002 included 978 term-born children, 348 boys and 630 girls, at the age of 7-10 years. Information concerning the birth weight of a child was obtained from the health records of the women. Information about the mother's and the father's smoking habits during pregnancy and about the mothers' education level was obtained from a questionnaire. The influence of parental smoking on relative leg length, controlled for age, sex, birth weight and the mother's education, as a proxy measure of socioeconomic status, and controlled for an interaction between sex and birth weight, was assessed by an analysis of covariance, where relative leg length was the dependent variable, smoking and sex were the independent variables, and birth weight as well as the mother's education were the covariates. Three separate analyses were run for the three models of smoking habits during pregnancy: the mother's smoking, the father's smoking and both parents' smoking. Only both parents' smoking showed a significant effect on relative leg length of offspring. It is probable that foetal hypoxia caused by carbon monoxide contained in smoke decelerated the growth of the long bones of foetuses.

Breastfeeding, Other Early Life Exposures and Childhood Leukemia and Lymphoma

Childhood cancer incidence increases and although rare, it is a leading cause of mortality. Leukemia and lymphoma comprise 40% of all cancers in children but little is known of their etiology. In this study, we examined the associations of breastfeeding and other early life exposures with childhood leukemia and lymphoma. A population-based case-control study carried out in 2011-2013 comprised mothers of 190 incidents (2005-2013) of leukemia/lymphoma cases aged 1-19 yr at diagnosis and 384 population-based controls. Interviews based on a computerized structured questionnaire were conducted with the mothers. Multivariate logistic regression models adjusted for potential confounders assessed the association between breastfeeding patterns and childhood leukemia/lymphoma. Ever breastfeeding category was associated with a 64% decreased risk for childhood leukemia/lymphoma lsqb;odds ratio (OR) = 0.36, 95% confidence interval (CI): 0.22, 0.60lrqb; and similar trends, with a dose-response effect, were observed for any breastfeeding (exclusive and/or partial) category for 6, 12, and 18+ mo. Other infant exposures associated with cancer risk were child iron supplementation (OR = 0.39, 95% CI: 0.26, 0.59), pet ownership (OR = 0.50, 95% CI: 0.33, 0.78), paternal smoking (OR = 1.93, 95% CI: 1.18, 3.15), and having older siblings (OR = 1.18, 95% CI: 1.05, 1.33). Breastfeeding-a controllable and modifiable exposure-is inversely associated with risk for childhood leukemia and lymphoma with a dose-response effect.

Cotinine and polycyclic aromatic hydrocarbons levels in the amniotic fluid and fetal cord at birth and in the urine from pregnant smokers

Cigarette smoking during pregnancy has several impacts on fetal development, including teratogenic effects. The objective of this study was to assess whether the toxic substances (cotinine and polycyclic aromatic hydrocarbons) found in pregnant smokers are transmitted to their fetuses. The outcomes were analyzed measuring cotinine and 1-hydroxypyrene in the amniotic fluid and maternal urine, benzopyrene and cotinine in the umbilical cord blood. Through a controlled cross-sectional design, 125 pregnant women were selected and classified according to their smoking status: 37 current smokers, 25 passive smokers and 63 non-smokers (controls). We performed high-performance liquid chromatography to measure substances’ concentrations. A post-hoc Tukey’s test was used to analyze the differences between the groups. All variables were significantly different between controls and smokers. The mean ratios between the concentration of cotinine in smokers compared to controls were as follows: 5.9 [2.5–13.5], p<0.001 in the urine; 25 [11.9–52.9], p<0.001 in the amniotic fluid; and 2.6 [1.0–6.8], p = 0.044 in the umbilical cord blood. The mean ratios of 1-hydroxypyrene concentration between smokers and controls were 7.3 [1.6–29.6], p = 0.003 in the urine and 1.3 [1.0–1.7], p = 0.012 in the amniotic fluid, and of benzopyrene in umbilical cord blood was 2.9 [1.7–4.7], p<0.001. There were no significant differences between controls and passive smokers. When comparing the three groups together, there were statistical differences between all variables. Thus, the fetuses of pregnant smokers are exposed to toxic and carcinogens substances. To our knowledge, this is the first study to measure 1-hydroxypyrene in the amniotic fluid and benzopyrene in umbilical cord blood by high-performance liquid chromatography when considering pregnant women in relation to smoking exposure only.

Tobacco smoke and risk of childhood acute non-lymphocytic leukemia: findings from the SETIL study

BACKGROUND

Parental smoking and exposure of the mother or the child to environmental tobacco smoke (ETS) as risk factors for Acute non-Lymphocytic Leukemia (AnLL) were investigated.

METHODS

Incident cases of childhood AnLL were enrolled in 14 Italian Regions during 1998-2001. We estimated odds ratios (OR) and 95% confidence intervals (95%CI) conducting logistic regression models including 82 cases of AnLL and 1,044 controls. Inverse probability weighting was applied adjusting for: age; sex; provenience; birth order; birth weight; breastfeeding; parental educational level age, birth year, and occupational exposure to benzene.

RESULTS

Paternal smoke in the conception period was associated with AnLL (OR for ≥ 11 cigarettes/day  = 1.79, 95% CI 1.01-3.15; P trend 0.05). An apparent effect modification by maternal age was identified: only children of mothers aged below 30 presented increased risks. We found weak statistical evidence of an association of AnLL with maternal exposure to ETS (OR for exposure>3 hours/day  = 1.85, 95%CI 0.97-3.52; P trend 0.07). No association was observed between AnLL and either maternal smoking during pregnancy or child exposure to ETS.

CONCLUSIONS

This study is consistent with the hypothesis that paternal smoke is associated with AnLL. We observed statistical evidence of an association between maternal exposure to ETS and AnLL, but believe bias might have inflated our estimates.

Neonatal tumours

Neonatal or perinatal tumours frequently relate to prenatal or developmental events and have a short exposure window which provides an opportunity to study tumours in a selective sensitive period of development. As a result, they display a number of host-specific features which include occasional spontaneous maturational changes with cells still responding to developmental influences. Neonatal tumours (NNT) are studied for a number of important reasons. Firstly, many of the benign tumours arising from soft tissue appear to result from disturbances in growth and development and some are associated with other congenital anomalies. Study of these aspects may open the door for investigation of genetic and epigenetic changes in genes controlling foetal development as well as environmental and drug effects during pregnancy. Secondly, the clinical behaviour of NNT differs from that of similar tumours occurring later in childhood. In addition, certain apparently malignant NNT can 'change course' in infancy leading to the maturation of apparently highly malignant tumours. Thirdly, NNT underline the genetic associations of most tumours but appear to differ in the effects of proto-oncogenes and other oncogenic factors. In this context, there are also connections between the foetal and neonatal period and some "adult" cancers. Fourthly, they appear to arise in a period in which minimal environmental interference has occurred, thus providing a unique potential window of opportunity to study the pathogenesis of tumour behaviour. This study will seek to review what is currently known in each of these areas of study as they apply to NNT. Further study of the provocative differences in tumour behaviour in neonates provides insights into the natural history of cancer in humans and promotes novel cancer therapies.

Polymorphisms in ERCC1 and XPF genes and risk of gastric cancer in an eastern Chinese population

BACKGROUND

Inherited functional single nucleotide polymorphisms (SNPs) in DNA repair genes may alter DNA repair capacity and thus contribute to cancer risk.

METHODS

Three ERCC1 functional SNPs (rs2298881C>A, rs3212986C>A and rs11615G>A) and two XPF/ERCC4 functional SNPs (rs2276466C>G and rs6498486A>C) were genotyped for 1125 gastric adenocarcinoma cases and 1196 cancer-free controls by Taqman assays. Odds ratios (OR) and 95% confidence intervals (CI) were used to estimate risk associations, and false-positive report probabilities (FPRP) were calculated for assessing significant findings.

RESULTS

ERCC1 rs2298881C and rs11615A variant genotypes were associated with increased gastric cancer risk (adjusted OR=1.33, 95% CI=1.05-1.67 for rs2298881 AC/CC and adjusted OR=1.23, 95% CI=1.05-1.46 for rs11615 AG/AA, compared with their common genotype AA and GG, respectively). Patients with 2-3 ERCC1 risk genotypes had significant increased risk (adjusted OR=1.56, 95% CI=1.27-1.93), compared with those with 0-1 ERCC1 risk genotypes, and this risk was more significantly in subgroups of never drinkers, non-gastric cardia adenocarcinoma (NGCA) and clinical stage I+II. All these risks were not observed for XPF SNPs.

CONCLUSIONS

These findings suggest that functional ERCC1 SNPs may contribute to risk of gastric cancer. Larger and well-designed studies with different ethnic populations are needed to validate our findings.

Transplacental carcinogenesis with dibenzo[def,p]chrysene (DBC): timing of maternal exposures determines target tissue response in offspring

Dibenzo[def,p]chrysene (DBC) is a transplacental carcinogen in mice (15mg/kg; gestation day (GD) 17). To mimic residual exposure throughout pregnancy, dams received four smaller doses of DBC (3.75mg/kg) on GD 5, 9, 13 and 17. This regimen alleviated the previously established carcinogenic responses in the thymus, lung, and liver. However, there was a marked increase in ovarian tumors (females) and hyperplastic testes (males). [(14)C]-DBC (GD 17) dosing revealed transplacental distribution to fetal tissues at 10-fold lower concentrations than in paired maternal tissue and residual [(14)C] 3weeks post-dose. This study highlights the importance of developmental stage in susceptibility to environmental carcinogens.

Transgenerational tobacco smoke exposure and childhood cancer: an observational study

AIM

Although tobacco smoke is an established risk factor for adult cancer, studies of the association between parental smoking and childhood cancer have produced inconsistent results. To investigate the transgenerational relationship between pre-natal and post-natal tobacco smoke exposure from the grandmother's pregnancies until after the post-natal period and childhood cancer.

METHODS

Exposure to tobacco smoke was recorded for three generations. Data were collected through personal interviews using the paediatric environmental history, and were compared among 128 children with cancer and 128 matched controls. The contingency tables and a logistic multivariable regression model were used to control for possible confounding factors.

RESULTS

Smoke exposure during oogenesis (maternal grandmother smokers)--odds ratio (OR) 2.2 (95% confidence interval (CI) 1.1-4.9)--and during the mother' pregnancies--OR 1.8 (95% CI 1.1-3.3)--were significantly associated with an increased risk of childhood cancer.

CONCLUSIONS

Tobacco smoke exposure during the grandmother's and mother's pregnancies increase the risk of cancer in the descendants. The results suggest that the biological plausibility of the association between parental smoking and paediatric cancer can be explained by the large latency period of paediatric carcinogenesis.

Long-term consequences of fetal and neonatal nicotine exposure: a critical review

Cigarette smoking during pregnancy is associated with numerous obstetrical, fetal, and developmental complications, as well as an increased risk of adverse health consequences in the adult offspring. Nicotine replacement therapy (NRT) has been developed as a pharmacotherapy for smoking cessation and is considered to be a safer alternative for women to smoking during pregnancy. The safety of NRT use during pregnancy has been evaluated in a limited number of short-term human trials, but there is currently no information on the long-term effects of developmental nicotine exposure in humans. However, animal studies suggest that nicotine alone may be a key chemical responsible for many of the long-term effects associated with maternal cigarette smoking on the offspring, such as impaired fertility, type 2 diabetes, obesity, hypertension, neurobehavioral defects, and respiratory dysfunction. This review will examine the long-term effects of fetal and neonatal nicotine exposure on postnatal health.

Cigarette smoking during pregnancy: chromosome translocations and phenotypic susceptibility in mothers and newborns

The effects of maternal cigarette smoking during pregnancy on structural chromosome aberrations were evaluated in peripheral lymphocytes from 239 mothers and their 241 newborns to determine whether smoking during pregnancy, genetic susceptibility, and race are associated with chromosome aberrations including translocations. Demographic information and cigarette smoking data were obtained via questionnaire. There were 119 Caucasian Americans, 118 African Americans, and 2 Asian Americans. The average maternal age was 24.9+/-5.8 (mean+/-S.D.) years. Thirty-nine percent of the Caucasian Americans and 45.4% of the African Americans self-reported that they were active smokers during the index pregnancy. The average number of cigarettes smoked per day was 2.65+/-5.75 and 1.37+/-3.17 for Caucasian and African American mothers, respectively. Peripheral blood lymphocytes from the mother and from the fetal side of the placenta were evaluated for chromosome aberrations by whole chromosome painting. Aliquots from the same blood samples were also used to assess genetic susceptibility with an in vitro bleomycin challenge assay. Spontaneous translocation frequencies in both maternal and newborn lymphocytes were not associated with cigarette smoking, socioeconomic status, or education. The absence of a smoking effect may be attributable to the low level of cigarette usage in these subjects. The average bleomycin-induced damage in the maternal and newborn populations was 0.37+/-0.27 and 0.15+/-0.14 breaks per cell, respectively, a difference that was highly significant (p<0.0001). In newborns there was a positive association between bleomycin sensitivity and the frequencies of aberrations as measured by chromosome painting: p Collapse

Key Words

• cigarette smoking
• pregnancy
• newborns
• mothers
• chromosome translocations
• genomic susceptibility

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MESH Headings

• Adolescent
• Adult
• Black or African American
• Chromobacterium
• Female
• Humans
• Infant, Newborn
• Male
• Maternal-Fetal Exchange
• Pregnancy
• Smoking/adverse effects
• Translocation, Genetic/genetics
• White People

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Grants

• R01 DE033016 NIDCR NIH HHS
• ZIJ BC011218-01 Intramural NIH HHS
• R01 HD33016 NICHD NIH HHS

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Affiliation(s)

L Michelle Bennett Physical and Life Sciences Directorate, L-452, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States.
Yun Wang
Marilyn J Ramsey
Gail F Harger
William L Bigbee
James D Tucker

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Early life insult from cigarette smoke may be predictive of chronic diseases later in life

Evidence is rapidly accumulating that links cigarette smoke (CS) exposure in utero with the development of a variety of disease pathologies in the older offspring including, type 2 diabetes, obesity, certain childhood cancers and respiratory disorders. The role that the fetal environment plays in these late-onset outcomes and the underlying cellular/molecular mechanisms by which these CS-induced effects may occur are currently unknown. Although we are becoming more aware of the fact that prenatal insult can underlie childhood/adult diseases, critical knowledge gaps still exist including gene-environment interactions, and how a CS-induced imbalance in immune dynamics (i.e. TH1/TH2) might affect asthma development and/or exacerbation later in life. In this mini-review we introduce the concept of sexual dimorphism in CS-induced late-onset disease outcomes, as well as explore the mechanisms by which CS exposure in utero can lead to cardiovascular, cancer and respiratory abnormalities in the exposed offspring. By addressing such questions using animal models, appropriate intervention strategies can be developed that will help to protect children's health and their long-term quality of life.

From the American Academy of Pediatrics: Technical report--Secondhand and prenatal tobacco smoke exposure

Secondhand tobacco smoke (SHS) exposure of children and their families causes significant morbidity and mortality. In their personal and professional roles, pediatricians have many opportunities to advocate for elimination of SHS exposure of children, to counsel tobacco users to quit, and to counsel children never to start. This report discusses the harms of tobacco use and SHS exposure, the extent and costs of tobacco use and SHS exposure, and the evidence that supports counseling and other clinical interventions in the cycle of tobacco use. Recommendations for future research, policy, and clinical practice change are discussed. To improve understanding and provide support for these activities, the harms of SHS exposure are discussed, effective ways to eliminate or reduce SHS exposure are presented, and policies that support a smoke-free environment are outlined.

Environmental tobacco smoke (ETS) and respiratory health in children

Environmental tobacco smoke (ETS) is a major risk factor for poor lung health in children. Although parental smoking is the commonest source of ETS exposure to children, they are also exposed to ETS in schools, restaurants, public places and public transport vehicles. Apart from containing thousands of chemicals, the particle size in the ETS is much smaller than the main stream smoke, and therefore has a greater penetrability in the airways of children. Exposure to ETS has been shown to be associated with increased prevalence of upper respiratory tract infections, wheeze, asthma and lower respiratory tract infections. Even developing fetuses are exposed to ETS via the umbilical cord blood if the mother is exposed to tobacco smoke. The placenta also does not offer any barrier to the penetration of ETS into the fetus. The immune system in these babies is more deviated toward the allergic and asthmatic inflammatory phenotype and therefore makes them more prone to develop asthma later in life. An increased awareness of the harmful effects of ETS on children's health is warranted.

Lymphoma and lung cancer in offspring born to pregnant mice dosed with dibenzo[a,l]pyrene: the importance of in utero vs. lactational exposure

The fetus and neonate cannot be viewed as "little adults"; they are highly sensitive to toxicity from environmental chemicals. This phenomenon contributes to the fetal basis of adult disease. One example is transplacental carcinogenesis. Animal models demonstrate that environmental chemicals, to which pregnant women are daily exposed, can increase susceptibility of the offspring to cancer. It is uncertain to what degree in utero vs. lactational exposure contributes to cancer, especially for hydrophobic chemicals such as polyhalogenated biphenyls, ethers, dioxins, furans, etc., which can partition into breast milk. We developed a pregnant mouse model in which exposure to the polycyclic aromatic hydrocarbon (PAH), dibenzo[a,l]pyrene (DBP), during late gestation, produces an aggressive T-cell lymphoma in offspring between 3 and 6 months of age. Survivors exhibit multiple lung and liver (males) tumors. Here, we adopt a cross-foster design with litters born to dams treated with DBP exchanged with those born to dams treated with vehicle. Exposure to DBP in utero (about 2 days) produced significantly greater mortality than residual DBP exposure only through breast milk (3 weeks of lactation). As previously observed pups in all groups with an ahr(b-1/d) ("responsive") genotype were more susceptible to lymphoma mortality than ahr(d/d) ("non-responsive") siblings. At termination of the study at 10 months, mice exposed in utero also had greater lung tumor multiplicity than mice exposed only during lactation. Our results demonstrate that short exposure to DBP during late gestation presents a greater risk to offspring than exposure to this very hydrophobic PAH following 3 weeks of nursing.

Second hand smoke, age of exposure and lung cancer risk

BACKGROUND

Exposure to second hand smoke (SHS) has been identified as a risk factor for lung cancer for three decades. It is also known that the lung continues to grow from birth to adulthood, when lung growth stops. We hypothesize that after adjusting for active cigarette smoking, if SHS exposure took place during the period of growth, i.e. in the earlier part of life (0-25 years of age) the risk of lung cancer is greater compared to an exposure occurring after age 25.

METHOD

Second hand smoke exposure was self-reported for three different activities (leisure, work and at home) for this study population of 1669 cases and 1263 controls. We created variables that captured location of exposure and timing of first exposure with respect to a study participant's age (0-25, >25 years of age). Multiple logistic regressions were used to study the association between SHS exposure and lung cancer, adjusting for age, gender and active smoking variables.

RESULT

For study participants that were exposed to SHS at both activities (work and leisure) and compared to one or no activity, the adjusted odds ratio (AOR) for lung cancer was 1.30 (1.08-1.57) when exposure occurred between birth and age 25 and 0.66 (0.21-1.57) if exposure occurred after age 25 years. Respective results for non-smokers were 1.29 (0.82-2.02) and 0.87 (0.22-3.38), and current and ex-smokers combined 1.28 (1.04-1.58) and 0.66 (0.15-2.85).

CONCLUSION

All individuals exposed to SHS have a higher risk of lung cancer. Furthermore, this study suggests that subjects first exposed before age 25 have a higher lung cancer risk compared to those for whom first exposure occurred after age 25 years.

Induction of V(D)J-mediated recombination of an extrachromosomal substrate following exposure to DNA-damaging agents

V(D)J recombinase normally mediates recombination signal sequence (RSS) directed rearrangements of variable (V), diversity (D), and joining (J) germline gene segments that lead to the generation of diversified T cell receptor or immunoglobulin proteins in lymphoid cells. Of significant clinical importance is that V(D)J-recombinase-mediated rearrangements at immune RSS and nonimmune cryptic RSS (cRSS) have been implicated in the genomic alterations observed in lymphoid malignancies. There is growing evidence that exposure to DNA-damaging agents can increase the frequency of V(D)J-recombinase-mediated rearrangements in vivo in humans. In this study, we investigated the frequency of V(D)J-recombinase-mediated rearrangements of an extrachromosomal V(D)J plasmid substrate following exposure to alkylating agents and ionizing radiation. We observed significant dose- and time-dependent increases in V(D)J recombination frequency (V(D)J RF) following exposure to ethyl methanesulfonate (EMS) and methyl methanesulfonate (MMS) but not a nonreactive analogue, methylsulfone (MeSulf). We also observed a dose-dependent increase in V(D)J RF when cells were exposed to gamma radiation. The induction of V(D)J rearrangements following exposure to DNA-damaging agents was not associated with an increase in the expression of RAG 1/2 mRNA compared to unexposed controls or an increase in expression of the DNA repair Ku70, Ku80 or Artemis proteins of the nonhomologous end joining pathway. These studies demonstrate that genotoxic alkylating agents and ionizing radiation can induce V(D)J rearrangements through a cellular response that appears to be independent of differential expression of proteins involved with V(D)J recombination.

Study of the telomerase hTERT fraction, PCNA and CD34 expression on pituitary adenomas. Association with clinical and demographic characteristics

To determine the frequency of human telomerase reverse transcriptase (hTERT) catalytic fraction expression and its association with clinical and demographic characteristics of the patient, as well as with the expression of CD34 and proliferating cell nuclear antigen (PCNA) indexes on adenohypophyseal hormone tissues. A transverse study was realized with 49 cases of hypophyseal adenoma with analysis type cases and controls. The different adenohypophyseal hormones [prolactin (PRL), growth hormone (GH), follicle stimulating hormone, luteinizing hormone, thyroid gland stimulant hormone, adrenocorticotropic hormone (ACTH)], the catalytic fraction of the telomerase hTERT, the PCNA index and the CD34 density were determined by means of immunohistochemical techniques. The clinical, demographic and histopathological characteristics of the patients with and without hTERT expression were compared by means of Pearson's Chi-squared, Fisher's exact test and Mann-Whitney's U. Twenty-eight point six percent of the adenomas had positive expression for hTERT. The variables significantly correlated with hTERT's expression were younger age of presentation, diagnostic of adenoma producer, higher PCNA index, higher CD34 density, increased GH on serum and the expression on PRL tissue, GH and ACTH. Tobacco history had a negative association with hTERT's expression. The telomerase could be a marker of cellular proliferation associated with angiogenesis and hormonal activity. Evaluation of these variables could provide information about their biological behavior.

Environmental tobacco smoke exposure and children's health

Almost half of the child population is involuntarily exposed to environmental tobacco smoke (ETS). The ETS exposure gives rise to an excessive risk of several diseases in infancy and childhood, including sudden infant death syndrome, upper and lower respiratory infections, asthma and middle ear diseases. It is also linked to cancer, and behavioural problems and neurocognitive deficits in children.

CONCLUSIONS

Protecting children from ETS exposure is a complex and important issue. The best improvement in children's health is to be gained when parents stop smoking or, when that is not possible, they stop smoking in their children's environment. Paediatricians, because of their authority, and their frequent and regular contact with parents, play a leading role in protecting children from ETS exposure. An ideal approach to help parents to stop smoking seems to be initial minimal-contact advice provided by their paediatrician with feedback and supplemental printed materials, leading to greater intensity and duration of follow-up home visits.

The economic impact of early life environmental tobacco smoke exposure: early intervention for developmental delay

BACKGROUND AND OBJECTIVES

Early-life exposure to environmental tobacco smoke (ETS) can result in developmental delay as well as childhood asthma and increased risk of cancer. The high cost of childhood asthma related to ETS exposure has been widely recognized; however, the economic impact of ETS-related developmental delay has been less well understood.

METHODS AND RESULTS

The Columbia Center for Children's Environmental Health (CCCEH) has reported adverse effects of prenatal ETS exposure on child development in a cohort of minority women and children in New York City (odds ratio of developmental delay = 2.36; 95% confidence interval 1.22-4.58). Using the environmentally attributable fraction (EAF) approach, we estimated the annual cost of one aspect of ETS-related developmental delay: Early Intervention Services. The estimated cost of these services per year due to ETS exposure is > Dollars 50 million per year for New York City Medicaid births and Dollars 99 million per year for all New York City births.

CONCLUSION

The high annual cost of just one aspect of developmental delay due to prenatal exposure to ETS provides further impetus for increased prevention efforts such as educational programs to promote smoke-free homes, additional cigarette taxes, and subsidizing of smoking cessation programs.

Environmental tobacco smoke exposure in school children: parent report and urine cotinine measures

BACKGROUND

Environmental tobacco smoke (ETS) in the home continues to be a major health risk for children around the world. Measuring ETS is a central feature of clinical and epidemiological studies, with children's exposure often assessed through parental estimates. The authors examined the relationship between parent-reported estimates of children's exposure to ETS and children's urinary cotinine levels and evaluated the ETS exposure and its effect on respiratory health in children.

METHODS

A total of 188 school children were included in the study. Parents were asked to complete a questionnaire about their smoking habits, their children's respiratory morbidity status and housing conditions. Urinary cotinine levels were measured in children.

RESULTS

According to the responses, 72.3% of the children came from households with smokers, and 34.6% had daily exposure to ETS. When urine cotinine levels of >10 ng/mL were used as the yardstick of exposure, 76% of the children were identified as ETS exposed. No relation was detected between the symptoms of respiratory tract diseases and ETS exposure. To determine the amount of ETS exposure, the contribution of parental reports was low.

CONCLUSION

To evaluate the level of ETS exposure of children, the parents' reports were not reliable. The addition of a biological measure results in a more informative estimate of ETS exposure in children.

Environmental tobacco smoke exposure: prevalence and mechanisms of causation of infections in children

BACKGROUND AND OBJECTIVES

Environmental tobacco smoke (ETS) exposure is probably one of the most important public health hazards in our community. Our aim with this article is to (1) review the prevalence of ETS exposure in the United States and how this prevalence is often measured in practice and (2) summarize current thinking concerning the mechanism by which this exposure may cause infections in young children.

METHODS

We conducted a Medline search to obtain data published mainly in peer-reviewed journals.

RESULTS

There is still a very high prevalence of ETS exposure among US children ranging from 35% to 80% depending on the method of measurement used and the population studied. The mechanism by which ETS may be related to these infections is not entirely clear but may be through suppression or modulation of the immune system, enhancement of bacterial adherence factors, or impairment of the mucociliary apparatus of the respiratory tract, or possibly through enhancement of toxicity of low levels of certain toxins that are not easily detected by conventional means.

CONCLUSIONS

The prevalence of ETS exposure in the United States is still very high, and its role in causing infections in children is no longer in doubt even if still poorly understood. Research, therefore, should continue to focus on the various mechanisms of causation of these infections and how to best reduce the exposure levels.

The Epithelial Cell in Lung Health and Emphysema Pathogenesis

Cigarette smoking is the primary cause of the irreversible lung disease emphysema. Historically, inflammatory cells such as macrophages and neutrophils have been studied for their role in emphysema pathology. However, recent studies indicate that the lung epithelium is an active participant in emphysema pathogenesis and plays a critical role in the lung's response to cigarette smoke. Tobacco smoke increases protease production and alters cytokine expression in isolated epithelial cells, suggesting that these cells respond potently even in the absence of a complete inflammatory program. Tobacco smoke also acts as an immunosuppressant, reducing the defense function of airway epithelial cells and enhancing colonization of the lower airways. Thus, the paradigm that emphysema is strictly an inflammatory-cell based disease is shifting to consider the involvement of resident epithelial cells. Here we review the role of epithelial cells in lung development and emphysema. To better understand tobacco-epithelial interactions we performed microarray analyses of RNA from human airway epithelial cells exposed to smoke extract for 24 hours. These studies identified differential regulation of 425 genes involved in diverse biological processes, such as apoptosis, immune function, cell cycle, signal transduction, proliferation, and antioxidants. Some of these genes, including VEGF, glutathione peroxidase, IL-13 receptor, and cytochrome P450, have been previously reported to be altered in the lungs of smokers. Others, such as pirin, cathepsin L, STAT1, and BMP2, are shown here for the first time to have a potential role in smoke-associated injury. These data broaden our understanding of the importance of epithelial cells in lung health and cigarette smoke-induced emphysema.

Maternal coffee and alcohol consumption during pregnancy, parental smoking and risk of childhood acute leukaemia

INTRODUCTION

We investigated the role of maternal alcohol and coffee drinking and parental smoking on the risk of childhood acute leukemia in a multicenter case-control study.

METHODS

The study included 280 incident cases and 288 hospitalized controls, frequency matched with the cases by age, gender and center. Data collection was completed by face-to-face standardized interviews of the case and control mothers.

RESULTS

An association with maternal alcohol consumption during pregnancy was observed with acute lymphoid leukemia (ALL) (OR=2.0 [1.4-3.0]) and acute non-lymphoid leukemia (ANLL) (OR=2.6 [1.2-5.8]). Maternal coffee consumption during pregnancy was associated with childhood acute leukemia, ORs increasing in ALL with coffee consumption (OR=1.1 [0.7-1.8], OR=2.4 [1.3-4.7] and OR=3.1 [1.0-9.5], respectively, for < or =3, 4-8 and >8 cups/day). No association with maternal smoking during pregnancy or parental smoking before or after the index child's birth was observed.

DISCUSSION

Our results suggest an association with maternal alcohol and coffee drinking during pregnancy and call for further investigations. Besides, the present study does not support the hypothesis of an increase in the risk of childhood leukemia related to parental smoking.

Effects of Prenatal Exposure to Cigarette Smoke on Offspring Tumor Susceptibility and Associated Immune Mechanisms

Epidemiologic evidence suggests that prenatal exposure to intact (unfractionated) cigarette smoke (CS) increases the incidence of cancer in the offspring. A toxicology study was carried out to examine the effects and underlying mechanisms of prenatal exposure to mainstream cigarette smoke (MCS) on offspring resistance to tumor challenge and surveillance mechanisms critical for the recognition and destruction of tumors. Pregnant B6C3F1 mice were exposed by inhalation to MCS for 5 days/week (4 h/day from gestational day 4 to parturition). Smoke-induced effects on offspring-host resistance to transplanted tumor cells; natural killer (NK) cell and cytotoxic T-lymphocyte (CTL) activity; cytokine levels; lymphoid organ immune cell subpopulations; and histology-were examined in 5-, 10- and 20-week-old male and female offspring. At a concentration of smoke roughly equivalent to smoking <1 pack of cigarettes/day, prenatally exposed male offspring challenged at 5 week of age with EL4 lymphoma cells demonstrated a greater than two-fold increase in tumor incidence (relative to age-/gender-matched air-exposed offspring); tumors in prenatally smoke-exposed pups also grew significantly faster. Cytotoxic T-lymphocyte activity in the smoke-exposed 5- and 10-week-old male pups was significantly less than that of the age- and gender-matched controls. No effects of prenatal CS exposure were observed on offspring NK activity, cytokine levels, lymphoid organ histology, or immune cell subpopulations. Results demonstrated that exposure of pregnant mice to a relevant dose of MCS decreased offspring resistance against transplanted tumor cells and persistently reduced CTL activity in prenatally exposed pups. This study provides biological plausibility for the epidemiologic data indicating that children of mothers who smoke during pregnancy have a greater risk of developing cancer in later life.

Nucleotide excision repair as a marker for susceptibility to tobacco-related cancers: a review of molecular epidemiological studies

DNA repair is a complicated biological process consisting of several distinct pathways that play a central role in maintaining genomic stability. Research on DNA repair and cancer risk is a vital, emerging field that recently has seen rapid advances facilitated by the completion of the Human Genome Project. In this review, we described phenotypic and genotypic markers of nucleotide excision repair (NER) that have been used in molecular epidemiology studies. We summarized the population-based studies to date that have examined the association between DNA repair capacity phenotype and genetic polymorphisms of the NER genes and risk of tobacco-related cancers, including cancers of the lung, head and neck, prostate, bladder, breast, and esophagus. We also included studies of melanoma and nonmelanoma skin cancers because individuals with defective NER, such as patients with xeroderma pigmentosum (XP) are highly susceptible to ultraviolet light (UV)-induced melanoma and nonmelanoma skin cancers. The published data provide emerging evidence that DNA repair capacity may contribute to genetic susceptibility to cancers in the general population. However, many of the studies are limited in terms of the size of the study populations. Furthermore, all published findings are still considered preliminary, the assays used in the studies have yet to be validated, and the results need to be confirmed. Large and well-designed population-based studies are warranted to assess gene-gene and gene-environment interactions and to ultimately determine, which biomarkers of DNA repair capacity are useful for screening high-risk populations for primary prevention and early detection of tobacco-related cancers.

Epidemiology of brain tumors in childhood--a review

Malignant brain tumors are the leading cause of cancer death among children and the second most common type of pediatric cancer. Despite several decades of epidemiologic investigation, the etiology of childhood brain tumors (CBT) is still largely unknown. A few genetic syndromes and ionizing radiation are established risk factors. Many environmental exposures and infectious agents have been suspected of playing a role in the development of CBT. This review, based on a search of the medical literature through August 2003, summarizes the epidemiologic evidence to date. The types of exposures discussed include ionizing radiation, N-nitroso compounds (NOC), pesticides, tobacco smoke, electromagnetic frequencies (EMF), infectious agents, medications, and parental occupational exposures. We have chosen to focus on perinatal exposures and review some of the recent evidence indicating that such exposures may play a significant role in the causation of CBT. The scientific community is rapidly learning more about the molecular mechanisms by which carcinogenesis occurs and how the brain develops. We believe that advances in genetic and molecular biologic technology, including improved histologic subtyping of tumors, will be of huge importance in the future of epidemiologic research and will lead to a more comprehensive understanding of CBT etiology. We discuss some of the early findings using these technologies.

Adverse health effects of prenatal and postnatal tobacco smoke exposure on children

Parents who choose to smoke are possibly not aware of, or deny, the negative effects of passive smoking on their offspring. This review summarises a wide range of effects of passive smoking on mortality and morbidity in children. It offers paediatricians, obstetricians, specialists in preventive child health care, general practitioners, and midwives an approach to promote smoking cessation in smoking parents before, during, and after pregnancy.

Ontogenic differences in human liver 4-hydroxynonenal detoxification are associated with in vitro injury to fetal hematopoietic stem cells

4-hydroxynonenal (4HNE) is a highly mutagenic and cytotoxic alpha,beta-unsaturated aldehyde that can be produced in utero during transplacental exposure to prooxidant compounds. Cellular protection against 4HNE injury is provided by alcohol dehydrogenases (ADH), aldehyde reductases (ALRD), aldehyde dehydrogenases (ALDH), and glutathione S-transferases (GST). In the present study, we examined the comparative detoxification of 4HNE by aldehyde-metabolizing enzymes in a panel of adult and second-trimester prenatal liver tissues and report the toxicological ramifications of ontogenic 4HNE detoxification in vitro. The initial rates of 4HNE oxidation and reduction were two- to fivefold lower in prenatal liver subcellular fractions as compared to adult liver, and the rates of GST conjugation of 4HNE were not detectable in either prenatal or adult cytosolic fractions. GSH-affinity purification of hepatic cytosol yielded detectable and roughly equivalent rates of GST-4HNE conjugation for the two age groups. Consistent with the inefficient oxidative and reductive metabolism of 4HNE in prenatal liver, cytosolic fractions prepared from prenatal liver exhibited a decreased ability to protect against 4HNE-protein adduct formation relative to adults. Prenatal liver hematopoietic stem cells (HSC), which constitute a significant percentage of prenatal liver cell populations, exhibited ALDH activities toward 4HNE, but little reductive or conjugative capacity toward 4HNE through ALRD, ADH, and GST. Cultured HSC exposed to 5 microM 4HNE exhibited a loss in viability and readily formed one or more high molecular weight 4HNE-protein adduct(s). Collectively, our results indicate that second trimester prenatal liver has a lower ability to detoxify 4HNE relative to adults, and that the inefficient detoxification of 4HNE underlies an increased susceptibility to 4HNE injury in sensitive prenatal hepatic cell targets.

Genomic and transcriptional alterations in mouse fetus liver after transplacental exposure to cigarette smoke

The transplacental exposure of fetuses to maternal cigarette smoke may increase the risk of developmental impairments, congenital diseases, and childhood cancer. The whole-body exposure of Swiss mice to environmental cigarette smoke (ECS) during pregnancy decreased the number of fetuses per dam, placenta weight, and fetus weight. ECS increased DNA adducts, oxidative nucleotide alterations, and cytogenetic damage in fetus liver. Evaluation by cDNA array of 746 genes showed that 61 of them were expressed in fetus liver under basal conditions. The oral administration of N-acetylcysteine (NAC) during pregnancy enhanced the expression of three genes only, including two glutathione S-transferases and alpha1-antitrypsin precursor, whose deficiency plays a pathogenetic role in congenital emphysema. Transplacental ECS upregulated the expression of 116 genes involved in metabolism, response to oxidative stress, DNA and protein repair, and signal transduction. NAC inhibited the ECS-related genetic damage and upregulation of most genes. ECS stimulated pro-apoptotic genes and genes downregulating the cell cycle, which may justify growth impairments in the developing fetus. Thus, both genetic and epigenetic mechanisms were modulated by ECS. Moreover, hypoxia-related genes and several oncogenes and receptors involved in proliferation and differentiation of leukocytes were induced in the fetal liver, which also bears hematopoietic functions.

Detection of DNA adducts in developing CD4+ CD8+ thymocytes and splenocytes following in utero exposure to benzo[a]pyrene

Environmental carcinogen exposure may play an important role in the incidence of cancer in children. In addition to environmental pollutants, maternal smoking during pregnancy may be a contributing factor. Major carcinogenic components of cigarette smoke and other combustion by-products in the environment include polycyclic aromatic hydrocarbons (PAH). Mouse offspring exposed during midpregnancy to the PAH, benzo[a]pyrene (B[a]P), show significant deficiencies in their immune functions, observed in late gestation which persist for at least 18 months. Tumor incidences in these progeny are 8 to 10-fold higher than in controls. We have demonstrated a significant reduction in thymocytes (CD4+ CD8+, CD4+ CD8+ Vbeta8+, CD4+ CD8+ Vgamma2+) from newborn and splenocytes (CD4+ CD8+) from 1-week-old mouse progeny exposed to B[a]P in utero. To investigate possible causes of the observed T cell reduction, we analyzed the thymocytes and splenocytes from progeny and maternal tissues for the presence of B[a]P-DNA adducts. Adducts were detected in maternal, placental and offspring lymphoid tissues at day 19 of gestation, at birth and 1-wk after birth. The presence of B[a]P-DNA adducts in immature T cells may, in part, explain the previously observed T cell immunosuppression and tumor susceptibility in mice exposed to B[a]P in utero. The effects of DNA lesions on progeny T cells may include interference with normal T-cell development. These results provide a possible explanation for the relationship between maternal smoking during pregnancy and childhood carcinogenesis.

Relation of childhood brain tumors to exposure of parents and children to tobacco smoke: the SEARCH international case-control study. Surveillance of Environmental Aspects Related to Cancer in Humans

The etiology of childhood brain tumors (CBTs) remains unknown. Tobacco smoke contains several known carcinogens and can induce DNA adducts in human placenta and hemoglobin adducts in fetuses. We present the results of an international case-control study to evaluate the association between CBTs and exposure of parents and children to cigarette smoke. The study was undertaken as part of the SEARCH program of the IARC. Nine centers in 7 countries were involved. The studies mainly covered the 1980s and early 1990s. Cases (1,218, ages 0-19 years) were children newly diagnosed with a primary brain tumor; there were 2,223 population-based controls. Most mothers who agreed to participate were interviewed in person at home. Odds ratios (ORs) were calculated by unconditional logistic regression, adjusted for age, sex and center, for all types of CBT combined, 4 CBT histotypes, 5 age groups and each center. There was no association between the risk of brain tumors in the child and parental smoking prior to pregnancy, maternal smoking or regular exposure to others' cigarette smoke during pregnancy at home or at work, or passive smoking by the child during the first year of life. These results did not change considering the child's age at diagnosis, the histologic type of tumor or center.

Environment, genome and cancer

Cancer is one of the most serious diseases that threaten human being today. To some degree, it is a genetic disease but environmental and other nongenetic factors clearly play a role in many stages of neoplastic process. Genetic factors by themselves are thought to explain only about 5% of all cancer. The remainder can be attributed to external, 'environment' factors that act in conjunction with both genetic and acquired susceptibility. Of note, part of the susceptibility is owing to the variety of human genome. So, environment, human genome and cancer have much to do with each other. Combining all of the information from epidemiology and from research works in laboratory with policy-making and clinical works, purifying the environment, giving special protection to the high risk population, the mortality of cancer may decrease gradually in the future.

Exposure to parental tobacco and alcohol use: effects on children's health and development

This review examines three ways in which parental tobacco and alcohol use compromises the physical and mental health of children: 1) direct exposure to the substances; 2) living with parents who may become ill from using these substances; and 3) children's modeling of parental substance use. Implications for prevention, intervention, and public education are discussed, and a reframing of the national dialogue on youth substance abuse is called for.

Risk factors for pediatric tumors of the central nervous system: results from a German population-based case-control study

BACKGROUND

From 1993 to 1997 we conducted two population-based case-control studies on childhood cancer and a variety of potential risk factors in Germany. One case group involved children under the age of 15 years having a tumor of the central nervous system (CNS).

PROCEDURE

For both studies, one conducted in the northwestern area of Germany, the other covering the whole of West Germany, incident cases were identified from the nationwide German Childhood Cancer Registry, and controls were randomly selected from complete population registration files.

RESULTS

In total 466 pediatric CNS tumor cases and 2,458 controls were available for analyses. We observed only few positive associations, namely, between CNS tumors and low birth weight [<2,500 g; odds ratio (OR), 1.73; 95% confidence interval (CI), 1.06-2.84], between ependymoma and maternal smoking during pregnancy (>10 cigarettes per day: OR, 4.71; 95% CI, 1.69-13.1), and between astrocytoma and exposure to wood preservatives (OR, 1.91; 95% CI, 1.22-3.01). CNS tumors were not associated with high birth weight, duration of breast feeding, maternal age at time of delivery, duration of gestation, previous fetal losses, paternal smoking during pregnancy, maternal alcohol consumption, the child's exposure to pesticides, maternal diagnostic X-ray examinations during pregnancy, X-ray examinations of the child, or exposure to residential magnetic fields.

CONCLUSIONS

Despite the large study population, we found only few factors that were associated with CNS tumors or one of the morphological subgroups. Therefore, our results suggest that aspects of the prenatal and neonatal period play only a minor role in the etiology of pediatric CNS tumors.

The miseries of passive smoking

Passive smoking is defined as an involuntary exposure to a combined but diluted cigarette sidestream smoke (SS, gas and particle phases that are evolved from the smoldering end of a cigarette while the smoker is not puffing) and the exhaled smoke from smokers. SS contains numerous cytotoxic substances such as polycyclic aromatic hydrocarbons (PAHs), aromatic amines, nitrosamines, heavy metals, poisonous gases, pesticide residues, and radioactive elements in quantities much higher than those found from the cigarette mainstream smoke (MS) which is puffed by smokers. Passive smoking is found to be the cause of death from cancers and cardiac disease. Furthermore, it damagingly involves reproductive organs, the nervous system, genetic materials, and is particularly hazardous to mother and child during pregnancy and to those with a history of asthma, chronic infections, induced or earned immune deficiency, or predisposed susceptibility.

Childhood cancer and parental use of tobacco: findings from the inter-regional epidemiological study of childhood cancer (IRESCC)

Parental smoking data have been re-abstracted from the interview records of the Inter-Regional Epidemiological Study of Childhood Cancer (IRESCC) to test further the hypothesis that paternal cigarette smoking is a risk factor for the generality of childhood cancer. Reported cigarette smoking habits for the parents of 555 children diagnosed with cancer in the period 1980-1983 were compared, in two separate matched pairs analyses, with similar information for the parents of 555 children selected from GP lists (GP controls) and for the parents of 555 hospitalized children (hospital controls). When cases were compared with GP controls there was a statistically significant positive trend (P = 0.02) between the risk of childhood cancer and paternal daily consumption of cigarettes before the pregnancy; there was no significant trend for maternal smoking habit. When cases were compared with hospital controls there was a statistically significant negative trend (P< 0.001) between the risk of childhood cancer and maternal daily consumption of cigarettes before the pregnancy; there was no significant trend for paternal smoking habit. Neither of the significant trends could be explained by adjustment for socioeconomic grouping, ethnic origin or parental age at the birth of the child, or by simultaneous analysis of parental smoking habits. Relations between maternal consumption of cigarettes and birth weights suggested that (maternal) smoking data were equally reliable for case and control subjects, although comparisons with national data suggested that the hospital control parents were unusually heavy smokers. These findings give some support for the hypothesis that paternal cigarette smoking is a potential risk factor for the generality of childhood cancers.