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F P Perera

Publications and source records attributed to F P Perera.

At least 19 recordsLinked to original sources
PubMed1999

Molecular epidemiologic research on the effects of environmental pollutants on the fetus.

Evidence shows that fetuses and infants are more affected than adults by a variety of environmental toxicants because of differential exposure, physiologic immaturity, and a longer lifetime over which disease initiated in early life can develop. In this article we review data on the effects of in utero exposure to common environmental contaminants, including polycyclic aromatic hydrocarbons (PAH), particulate matter and environmental tobacco smoke (ETS). We then summarize results from our molecular epidemiologic study to assess risks from in utero exposures to ambient air pollution and ETS. This research study, conducted in Poland, used biomarkers to measure the internal and bioeffective dose of toxicants and individual susceptibility factors. The study included 160 mothers and 160 newborns. Ambient air pollution was significantly associated (p= 0.05) with the amount of PAH bound to DNA (PAH-DNA adducts) in both maternal and infant cord white blood cells (WBC). Newborns with elevated PAH-DNA adducts (greater than the median) had significantly decreased birth weight (p= 0.05), birth length (p= 0.02), and head circumference (p= 0.0005) compared to the newborns with lower adducts (n= 135). Maternal and infant cotinine levels were increased by active and passive cigarette smoke exposure of the mother (p= 0.01). An inverse correlation was seen between newborn plasma cotinine (nanograms per milliliter) and birth weight (p= 0.0001) and length (p= 0.003). Adducts were elevated in placental tissue and WBC of newborns who were heterozygous or homozygous for the cytochrome P4501A1 MspI restriction fragment length polymorphism (RFLP) compared to newborns without the RFLP. Levels of PAH-DNA and cotinine were higher in newborns than mothers. These results document that there is significant transplacental transfer of PAH and ETS constituents from mother to fetus; that PAH-DNA adduct levels in maternal and newborn WBC were increased with environmental exposure to PAH from ambient pollution; and that the fetus is more sensitive to genetic damage than the mother. The study also provided the first molecular evidence that transplacental PAH exposure to the fetus is compromising fetal development. If confirmed, these findings could have significant public health implications since a number of studies have found that reduction of head circumference at birth correlates with lower intelligence quotient as well as poorer cognitive functioning and school performance in childhood.

Adult↗
PubMed1999

Molecular and genetic damage from environmental tobacco smoke in young children.

To assess the risks of early life exposure to environmental tobacco smoke (ETS), we tested whether four biomarkers in peripheral blood were associated with home ETS exposure in Hispanic and African-American children. The biomarkers included cotinine (a metabolite of nicotine) and three indicators of molecular and genetic damage from mutagens/carcinogens, protein adducts formed by the carcinogens 4-aminobiphenyl (4-ABP) and polycyclic aromatic hydrocarbons (PAHs), and sister chromatid exchanges (SCEs). We also explored possible ethnic differences in biomarkers. The study cohort comprised 109 Hispanic and African-American preschool children (1-6 years of age). Plasma cotinine was analyzed by gas chromatography, 4-ABP-hemoglobin adducts by gas chromatography-mass spectroscopy, PAH-albumin adducts by ELISA, and SCEs by cytogenetic techniques. Data on the amount of smoking by mothers (average 10.5 cigarettes per day) and other household members and regular visitors (average 6.5 cigarettes per day) were obtained by interview-administered questionnaires. Cotinine, 4-ABP-hemoglobin adducts, and PAH-albumin were significantly higher (P < 0.05) in the ETS-exposed children compared with the unexposed. SCEs were marginally higher (P = 0.076). African-American children had higher levels of cotinine (P = 0.059) and PAH-albumin (P = 0.02) than Hispanic children, after controlling for exposure to ETS. These results indicate molecular and genetic damage in minority children with

Aminobiphenyl Compounds↗
PubMed1998

Recent developments in molecular epidemiology: A study of the effects of environmental polycyclic aromatic hydrocarbons on birth outcomes in Poland.

The authors briefly review the current potential and limitations of molecular epidemiology. This approach uses biomarkers to measure the internal and bioeffective dose of toxicants, early biologic effects likely to be predictive of cancer, and variations in individual susceptibility. The most frequent application of biomarkers has been in assessment of exposure/dose and susceptibility due to genetic and nongenetic factors. More research is needed to establish the predictive significance of biomarkers in terms of disease risk. To illustrate that molecular epidemiology has potential in identifying etiologic factors in disease, this article presents data from a recent study of the developmental effects of fetal exposure to polycyclic aromatic hydrocarbons (PAH) via ambient pollution. The study was carried out in an industrialized area of Poland with relatively high levels of PAH pollution from coal burning. PAH-DNA adducts in leukocytes and plasma cotinine were measured in umbilical cord blood as dosimeters of transplacental PAH and cigarette smoke, respectively. The study subjects were 70 newborns from the industrialized city of Krakow and 90 newborns from Limanowa, a rural town with far greater use of coal for home heating. Newborns whose levels of PAH-DNA adducts were above the median (3.85/10[8] nucleotides) had a significantly decreased birth length, weight, and head circumference. Cotinine was significantly inversely associated with birth weight and length. Although preliminary, these results provide a new molecular link between PAH exposure and developmental effects, generating initial data and hypotheses for further study.

Adult↗
PubMed1998

Molecular epidemiology of environmental carcinogenesis.

Environmental factors such as smoking, diet, and pollutants act in concert with individual susceptibility to cause most human cancers. This article briefly reviews molecular evidence that two types of susceptibility factors--common predisposing genetic traits and young age at exposure--convey heightened risk from certain exposures. Examples are drawn from molecular epidemiologic studies of common environmental carcinogens such as polycyclic aromatic hydrocarbons (PAH) and aromatic amines. Understanding of both genetic and acquired susceptibility in the population will be instrumental in developing health and regulatory policies that adequately protect of the more susceptible groups from risks of environmental carcinogens.

Adolescent↗
PubMed1998

Associations between both genetic and environmental biomarkers and lung cancer: evidence of a greater risk of lung cancer in women smokers.

This molecular epidemiologic case-control study of lung cancer incorporated three complementary biomarkers: the glutathione S-transferase M1 (GSTM1) null genotype, a potential marker of susceptibility, and polycyclic aromatic hydrocarbon-DNA adducts (PAH-DNA) and sister chromatid exchanges (SCE), both indicators of environmentally induced genetic damage. Associations between biomarkers and lung cancer were investigated, as were possible gene-environment interactions between the GSTM1 null genotype and tobacco smoke exposure. Subjects included 136 primary non-small cell lung cancer surgical patients and 115 controls at the Columbia Presbyterian Medical Center. Questionnaire and Tumor Registry data, pre-treatment blood samples and biomarker measurements on blood were obtained. Overall, GSTM1 null genotype was significantly associated with lung cancer [odds ratio (OR) = 2.04, 95% confidence interval (CI) = 1.13-3.68]. ORs for GSTM1 and lung cancer were significant in females (2.50, 1.09-5.72) and smokers (2.25, 1.11-4.54) and not significant in males (1.4, 0.58-3.38) and non-smokers (0.88, 0.18-4.33). However, ORs for males versus females and smokers versus non-smokers did not differ significantly. The OR for GSTM1 and lung cancer in female smokers was 3.03 (1.09-8.40), compared with 1.42 (0.53-4.06) in male smokers. In contrast to PAH-DNA adducts in leukocytes, SCE did not differ between cases and controls. Neither biomarker differed significantly between the two GSTM1 genotypes. The combined effect of elevated PAH-DNA adducts and GSTM1 genotype on case-control status (16.19, 1.2-115) appeared multiplicative. Results suggest that the effect of the GSTM1 null genotype is greatest in female smokers, which is consistent with other evidence that indicates that women are at higher risk of lung cancer than males, given equal smoking. Persons with both the GSTM1 deletion and elevated PAH-DNA adducts may represent a sensitive subpopulation with respect to carcinogens in tobacco smoke and other environmental media.

Adult↗
PubMed1998

Polycyclic aromatic hydrocarbon-DNA adducts in human placenta and modulation by CYP1A1 induction and genotype.

This study investigated the relationship in human placenta between polycyclic aromatic hydrocabon (PAH)-DNA adduct levels and two biomarkers of cytochrome P4501A1 (CYP1A1): gene induction evidenced by CYP1A1 mRNA, and a genetic polymorphism, the CYP1A1 MspI RFLP. CYP1A1 codes for an inducible enzyme system that catalyzes the bioactivation of PAHs. Prior research found a high correlation in human lung tissue between CYP1A1 activity and DNA damage from PAHs. The CYP1A1 Mspi RFLP has been linked in some studies to risk of lung cancer. The relationships in human placenta between DNA damage, CYP1A1 activity and genotype have not been well characterized and may be relevant to risks from transplacental PAH exposure. The study cohort consisted of 70 newborns from Krakow, Poland, a city with elevated air pollution, and 90 newborns from nearby Limanowa, an area with lower air pollution but greater indoor coal use. Contrary to results seen previously in lung tissue, CYP1A1 mRNA was not significantly correlated with PAH-DNA adduct levels in the placenta. Smoking (self-reported maternal and infant plasma cotinine) was significantly associated with CYP1A1 mRNA levels (P < 0.01), but not with PAH-DNA adduct levels. Placental PAH-DNA adduct levels were significantly higher in infants with the CYP1A1 MspI restriction site compared with infants without the restriction site (P < 0.01), implicating a genetic factor in inter-individual variation in DNA damage in human placenta. Further studies are needed to determine the relevance of this finding to risk of transplacental carcinogenesis.

Adult↗
PubMed1998

Children's health and the environment: a new agenda for prevention research.

Patterns of illness in American children have changed dramatically in this century. The ancient infectious diseases have largely been controlled. The major diseases confronting children now are chronic and disabling conditions termed the "new pediatric morbidity"--asthma mortality has doubled; leukemia and brain cancer have increased in incidence; neurodevelopmental dysfunction is widespread; hypospadias incidence has doubled. Chemical toxicants in the environment as well as poverty, racism, and inequitable access to medical care are factors known and suspected to contribute to causation of these pediatric diseases. Children are at risk of exposure to over 15,000 high-production-volume synthetic chemicals, nearly all of them developed in the past 50 years. These chemicals are used widely in consumer products and are dispersed in the environment. More than half are untested for toxicity. Children appear uniquely vulnerable to chemical toxicants because of their disproportionately heavy exposures and their inherent biological susceptibility. To prevent disease of environmental origin in America's children, the Children's Environmental Health Network (CEHN) calls for a comprehensive, national, child-centered agenda. This agenda must recognize children's vulnerabilities to environmental toxicants. It must encompass a) a new prevention-oriented research focus; b) a new child-centered paradigm for health risk assessment and policy formulation; and c) a campaign to educate the public, health professionals, and policy makers that environmental disease is caused by preventable exposures and is therefore avoidable. To anchor the agenda, CEHN calls for long-term, stable investment and for creation of a national network of pediatric environmental health research and prevention centers.

Child↗
PubMed1998

Relationship between ambient air pollution and DNA damage in Polish mothers and newborns.

Industrialized regions in Poland are characterized by high ambient pollution, including polycyclic aromatic hydrocarbons (PAHs) from coal burning for industry and home heating. In experimental bioassays, certain PAHs are transplacental carcinogens and developmental toxicants. Biologic markers can facilitate evaluation of effects of environmental PAHs on the developing infant. We measured the amount of PAHs bound to DNA (PAH-DNA adducts) in maternal and umbilical white blood cells. The cohort consisted of 70 mothers and newborns from Krakow, Poland, an industrialized city with elevated air pollution. Modulation of adduct levels by genotypes previously linked to risk of lung cancer, specifically glutathione S-transferase MI (GSTM1) and cytochrome P4501A1 (CYP1A1) Msp restriction fragment length polymorphism (RFLP), was also investigated. There was a dose-related increase in maternal and newborn adduct levels with ambient pollution at the women's place of residence among subjects who were not employed away from home (p < or = 0.05). Maternal smoking (active and passive) significantly increased maternal (p < or = 0.01) but not newborn adduct levels. Neither CYP1A1 Msp nor GSTM1 polymorphisms was associated with maternal adducts. However, adducts were significantly higher in newborns heterozygous or homozygous for the CYP1A1 Msp RFLP compared to newborns without the RFLP (p = 0.04). Results indicate that PAH-induced DNA damage in mothers and newborns is increased by ambient air pollution. In the fetus, this damage appears to be enhanced by the CYP1A1 Mspl polymorphism.

Adult↗
PubMed1998

The U.S. EPA Conference on Preventable Causes of Cancer in Children: a research agenda.

On 15-16 September 1997, the U.S. Environmental Protection Agency sponsored the Conference on Preventable Causes of Cancer in Children. The conference was convened to examine rising trends in reported incidence of childhood cancer and the association of these trends with environmental exposures. This paper summarizes recommendations for future research offered by participants. These recommendations included more collaborative research integrating epidemiology, molecular biology, toxicology, and risk assessment; the development of better protocols for toxicologic testing including carcinogenicity using young animals; and research focused on specific periods of development during which susceptibility to environmental agents may be enhanced. Also recommended was enhanced use and development of molecular biomarkers for identification of susceptible populations, and documentation of exposures and effects in epidemiologic and toxicologic studies. Although toxicologic testing is considered essential to determine the effects of potential carcinogens on biological organisms, participants emphasized the need to link these findings with epidemiologic and exposure assessment research.

Age Factors↗
PubMed1998

Organochlorine compounds (DDE and PCB) in plasma and breast cyst fluid of women with benign breast disease.

The organochlorines, dichloro-diphenyl-trichloroethane and polychlorinated biphenyl (PCB) are pervasive environmental contaminants. Results from previous studies have been conflicting regarding the relationship between the internal dose of these organochlorine residues and breast cancer risk. To determine whether these compounds are present in breast cyst fluids and whether cyst fluid and plasma concentrations are correlated, we analyzed organochlorines in paired cyst fluid and plasma samples from 24 subjects using gas chromatography and electron capture detection. All but one of the women had a history of multiple cysts, suggesting that they were at elevated risk for future breast cancer. DDE (a metabolite of dichloro-diphenyl-trichloroethane) was present in 22 of the cyst samples and PCB was detected in 19 of the cyst samples. Organochlorine levels were more concentrated in the plasma than in breast cyst fluids. Levels of DDE in plasma were significantly correlated with those in cyst fluid (r = 0.73; P < 0.001); in contrast to PCB levels in cyst and plasma (r = 0.37; P = 0.12). Congener specific analysis of the PCBs showed that some individual congeners were preferentially excluded from or concentrated in the cyst fluid. To our knowledge, this study is the first to demonstrate that PCB and DDE are present in cyst fluids and thus in contact with the ductal epithelium of the breast. These results support the use of plasma DDE as a proxy for DDE in the target tissue in research on the role of environmental factors in breast cancer.

Adult↗
PubMed1997

Environment and cancer: who are susceptible?

Acting in concert with individual susceptibility, environmental factors such as smoking, diet, and pollutants play a role in most human cancer. However, new molecular evidence indicates that specific groups-characterized by predisposing genetic traits or ethnicity, the very young, and women-may have heightened risk from certain exposures. This is illustrated by molecular epidemiologic studies of environmental carcinogens such as polycyclic aromatic hydrocarbons and aromatic amines. Individual genetic screening for rare high-risk traits or for more common, low-penetrant susceptibility genes is problematic and not routinely recommended. However, knowledge of the full spectrum of both genetic and acquired susceptibility in the population will be instrumental in developing health and regulatory policies that increase protection of the more susceptible groups from risks of environmental carcinogens. This will necessitate revision of current risk assessment methodologies to explicitly account for individual variation in susceptibility to environmental carcinogens.

Aging↗
PubMed1997

Aromatic DNA adducts in foundry workers in relation to exposure, life style and CYP1A1 and glutathione transferase M1 genotype.

Levels of aromatic DNA adducts in foundry workers and controls were followed at four annual samplings. During this time exposure to polycyclic aromatic hydrocarbons (PAH) decreased and the level of DNA adducts decreased accordingly. In the total group exposure was related to the level of adducts. Adduct levels correlated with urinary 1-hydroxypyrene (LOGU1OH), air benzo[a]pyrene, weekly working hours and daily cigarette consumption. In a multivariate model 1-hydroxypyrene had a consistent effect. Neither glutathione transferase M1 (GSTM1) nor cytochrome P450 1A1 (CYP1A1) genotypes had clear effects. Yet the individuals lacking GSTM1 had a stronger effect of LOGU1OH and some effect by other sources of PAH, such as charcoal broiled food, although all these variables were not significant in the multivariate model. The rare individuals with a CYP1A1 polymorphism MspI containing an amino acid change at isoleucine had an increased level of adducts. The results showed that the postlabelling method used was able to detect an increase in aromatic DNA adducts in leukocytes when exposure to benzo[a]pyrene in air was approximately 5 ng/m3. At such low levels smoking and charcoal broiled food may be important contributors to adducts.

Adult↗
PubMed1997

Contribution of genetic and nutritional factors to DNA damage in heavy smokers.

Prior epidemiological evidence suggests that genes controlling the metabolism of carcinogens and antioxidant/nutritional status are associated with lung cancer risk, possibly through their ability to modulate DNA damage by carcinogens. We performed a cross-sectional analysis of 159 heavy smokers from a cohort of subjects enrolled in a smoking cessation program. A total of 159 blood samples were analyzed to determine the relative contributions of genetic polymorphisms [CYP1A1 MspI and exon 7 and glutathione S-transferase M1 (GSTM1)] and plasma micronutrients to polycyclic aromatic hydrocarbon-DNA (PAH-DNA) adduct levels. DNA damage in smokers was affected by genetic polymorphisms and nutritional status. Smokers with the CYP1A1 exon 7 valine polymorphism had significantly higher (2-fold, P < or = 0.03) levels of DNA damage than those without. In parallel models, PAH-DNA adducts were inversely associated with plasma levels of retinol (beta = -0.93, P = 0.01), beta-carotene (beta = -0.18, P = 0.09), and alpha-tocopherol (beta = -0.28, P = 0.21) in 159 subjects. The association between smoking-adjusted plasma beta-carotene levels and DNA damage was only significant in those subjects lacking the GSTM1 detoxification gene (beta = -0.30, P = 0.05, n = 75). There was a statistical interaction between beta-carotene and alpha-tocopherol; when beta-carotene was low, alpha-tocopherol had a significant protective effect (beta = -0.78, P = 0.04) on adducts, but not when beta-carotene was high (beta = -0.16, P = 0.57). Plasma alpha-tocopherol was significantly correlated with beta-carotene (r = 0.36, P = 0.0005) and less strongly with retinol (r = 0.20, P = 0.0005). These results suggest that several micronutrients may act in concert to protect against DNA damage and highlight the importance of assessing overall antioxidant status. In conclusion, a subset of smokers may be at increased risk of DNA damage and possibly lung cancer due to the combined effect of low plasma micronutrients and genetic susceptibility factors. The use of biological markers to assess efficacy of interventions and to study mechanisms of micronutrients is timely given the current debate regarding the use of chemopreventive agents in high risk populations.

Adult↗
PubMed1997

Variability in PAH-DNA adduct measurements in peripheral mononuclear cells: implications for quantitative cancer risk assessment.

Biomarkers such as DNA adducts have significant potential to improve quantitative risk assessment by characterizing individual differences in metabolism of genotoxins and DNA repair and accounting for some of the factors that could affect interindividual variation in cancer risk. Inherent uncertainty in laboratory measurements and within-person variability of DNA adduct levels over time are putatively unrelated to cancer risk and should be subtracted from observed variation to better estimate interindividual variability of response to carcinogen exposure. A total of 41 volunteers, both smokers and nonsmokers, were asked to provide a peripheral blood sample every 3 weeks for several months in order to specifically assess intraindividual variability of polycyclic aromatic hydrocarbon (PAH)-DNA adduct levels. The intraindividual variance in PAH-DNA adduct levels, together with measurement uncertainty (laboratory variability and unaccounted for differences in exposure), constituted roughly 30% of the overall variance. An estimated 70% of the total variance was contributed by interindividual variability and is probably representative of the true biologic variability of response to carcinogenic exposure in lymphocytes. The estimated interindividual variability in DNA damage after subtracting intraindividual variability and measurement uncertainty was 24-fold. Inter-individual variance was higher (52-fold) in persons who constitutively lack the Glutathione S-Transferase M1 (GSTM1) gene which is important in the detoxification pathway of PAH. Risk assessment models that do not consider the variability of susceptibility to DNA damage following carcinogen exposure may underestimate risks to the general population, especially for those people who are most vulnerable.

Adult↗
PubMed1997

[Classification exposure error in studies on tobacco smoke in pregnancy and birth weight of newborns].

The purpose of the paper was to assess the validity of the self-reported tobacco smoke exposure in pregnancy against plasma cotinine measurements. A total of 158 patients from obstetrical wards was included in the cotinine study. Biochemical smokers were defined as persons with serum cotinine levels greater than 25 ng/ml. The data showed that the exposure classification based on self-reported smoking habit status confronted with cotinine values was of low sensitivity (52%) but of high specificity (98%). To assess the effect of this exposure classification error on the association between the low birth weight (LBW) and smoking in pregnancy, the data from the recent survey in Cracow children have been used. It was shown that RR estimates for smoking and LBW after adjustment for misclassification error were substantially higher than that not adjusted (crude RR = 2.9, corrected RR = 5.1). Due to the exposure misclassification error the attributable fraction (AF) of LBW due to mother's smoking was heavily biased as well. Estimated attributable fraction AF(pop) based on crude RR amounted to 22%, however, after adjustment reached 50%. The corresponding values for attributable fraction in exposed group AF(exp) were 66% and 80%.

Environmental Exposure↗
PubMed1997

Transitional studies.

Transitional studies are studies using biological markers that bridge the gap between laboratory experiments and population-based epidemiology. The goal of these studies is to characterize and validate biomarkers and to assess the following: intra- and inter-subject variability; the feasibility of marker use in field conditions; confounding and effect-modifying factors for the marker; and mechanisms reflected by the biomarker. Another goal is to optimize the conditions for the use of biomarkers. Transitional studies involving biomarkers of exposure or effect are distinguished from etiological studies because the biomarker is generally the outcome or dependent variable. Despite this difference, transitional studies can be epidemiological studies, but they may also include laboratory studies to assess reliability (and accuracy) and to identify parameters for collecting, processing and storing biological specimens prior to assay. Generally, transitional studies involve healthy people, patients or workers with specific exposures. At some point in the validation of a biomarker the line between transitional and etiological studies becomes blurred. None the less, it is useful to identify transitional studies as a distinct set of efforts to validate and characterize biomarkers. Transitional studies can be divided into three functional categories: developmental, characterization and applied studies.

Animals↗
PubMed1996

Molecular epidemiology: insights into cancer susceptibility, risk assessment, and prevention.

Recent molecular epidemiologic research provides compelling new evidence that environmental factors are major contributors to human cancer and that their risks are strongly influenced by genetic and acquired susceptibility. In particular, molecular epidemiology has demonstrated substantial variability in biologic response to carcinogens and suggests that certain groups-such as the very young, those with predisposing genetic traits or nutritional deficits, and even certain ethnic groups-are likely to have greater risk from selected exposures than other members of the population. This work implies that major gains in prevention of cancer, which will claim more than 554 000 American lives this year, will necessitate health and regulatory policies that protect these more susceptible groups and individuals from risks of man-made and naturally occurring environmental carcinogens. The specific implication from this research is that, to be effective in prevention, risk assessments developed in support of these policies by regulatory bodies, such as the Environmental Protection Agency, should reflect the available scientific data on individual variability in both exposure and susceptibility.

DNA Repair↗