Prenatal dichlorodiphenyldichloroethylene (DDE) and asthma in children

DNA hypomethylation at ALOX12 is associated with persistent wheezing in childhood

RATIONALE

Epigenetic changes may play a role in the occurrence of asthma-related phenotypes.

OBJECTIVES

To identify epigenetic marks in terms of DNA methylation of asthma-related phenotypes in childhood, and to assess the effect of prenatal exposures and genetic variation on these epigenetic marks.

METHODS

Data came from two cohorts embedded in the Infancia y Medio Ambiente (INMA) PROJECT: Menorca (n = 122) and Sabadell (n = 236). Wheezing phenotypes were defined at age 4-6 years. Cytosine-guanine (CpG) dinucleotide site DNA methylation differences associated with wheezing phenotypes were screened in children of the Menorca study using the Illumina GoldenGate Panel I. Findings were validated and replicated using pyrosequencing. Information on maternal smoking and folate supplement use was obtained through questionnaires. Dichlorodiphenyldichloroethylene was measured in cord blood or maternal serum. Genotypes were extracted from genome-wide data.

MEASUREMENT AND MAIN RESULTS

Screening identified lower DNA methylation at a CpG site in the arachidonate 12-lipoxygenase (ALOX12) gene in children having persistent wheezing compared with those never wheezed (P = 0.003). DNA hypomethylation at ALOX12 loci was associated with higher risk of persistent wheezing in the Menorca study (odds ratio per 1% methylation decrease, 1.13; 95% confidence interval, 0.99-1.29; P = 0.077) and in the Sabadell study (odds ratio, 1.16; 95% confidence interval, 1.03-1.37; P = 0.017). Higher levels of prenatal dichlorodiphenyldichloroethylene were associated with DNA hypomethylation of ALOX12 in the Menorca study (P = 0.033), but not in the Sabadell study (P = 0.377). ALOX12 DNA methylation was strongly determined by underlying genetic polymorphisms.

CONCLUSIONS

DNA methylation of ALOX12 may be an epigenetic biomarker for the risk of asthma-related phenotypes.

DDT and Other Chlorinated Insecticides

The use of organochlorine insecticides such as DDT, lindane and cyclodieneshas declined markedly worldwide over the last decades. Most are now banned or not used. At an acute toxicity level they have been relatively safe in use for humans. However, the greatest concerns are their persistence in people, wildlife and the environment due to their slow metabolism. Although their carcinogenicity for humans has not been supported by strong epidemiological evidence, their potential to be modulators of endocrine and immune function at levels remaining in the environment or associated with residual spraying of DDT continue to be of concern. At present, DDT is still allowed by the United Nations for combating malaria, with continual monitoring and assessment where possible. The toxicological consequences of exposure of animals and people to DDT is discussed as well as some analogues and other insecticides such as lindane, dieldrin and chlordecone that, although little used, continue to persist in surroundings and people. Because of circumstances of world health brought about by climate change or human activities that have yet to develop, there may come a time when the importance of some may re-emerge.

Biomonitoring and biomarkers to unravel the risks from prenatal environmental exposures for later health outcomes

An increasing number of studies have addressed the concern that environmental pollutants may contribute to the early origin of diseases. Epidemiologic studies suggest that prenatal exposure to air pollutants, several food contaminants, and chemicals present in consumer products are associated with nongenetically transmitted adverse health effects, which manifest after birth. Changes in neurobehavior, sexual development, the prevalence of asthma and allergy, and growth curves have been shown to be associated with pollutant exposure at early life stages. This review focuses on human molecular epidemiologic studies that contribute knowledge by introducing biomarker measurements to obtain a mechanistic understanding of the relation between early life exposures and health outcome. It has been hypothesized that subtle effects induced by pollutant exposure during development can lead to functional deficits and altered programming, which leads to increased disease or dysfunction risk later in life. Biomarker analysis may provide sensitive tools to trace these subtle changes and obtain mechanistic insight about the causal pathway between external exposure and health effects in human population studies. Biomarkers of exposure can be measured in mothers before conception, during pregnancy, or after birth. Different biological tissues-such as peripheral or cord blood samples, hair samples, meconium, and urine-provide specific information that reflects the actual dose during pregnancy or at birth. Biomarkers of effect may include changes in hormone concentrations, oxidative stress variables, changes in gene expression levels, and epigenetic changes.

Concentration of DDT compounds in breast milk from African women (Manhiça, Mozambique) at the early stages of domestic indoor spraying with this insecticide

Breast milk concentrations of 4,4'-DDT and its related compounds were studied in samples collected in 2002 and 2006 from two populations of mothers in Manhiça, Mozambique. The 2006 samples were obtained several months after implementation of indoor residual spraying (IRS) with DDT for malaria vector control in dwellings and those from 2002 were taken as reference prior to DDT use. A significant increase in 4,4'-DDT and its main metabolite, 4,4'-DDE, was observed between the 2002 (median values 2.4 and 0.9 ng/ml, respectively) and the 2006 samples (7.3 and 2.6 ng/ml, respectively, p<0.001 and 0.019, respectively). This observation identifies higher body burden intakes of these compounds in pregnant women already in these initial stages of the IRS program. The increase in both 4,4'-DDT and 4,4'-DDE suggest a rapid transformation of DDT into DDE after incorporation of the insecticide residues. The median baseline concentrations in breast milk in 2002 were low, and the median concentrations in 2006 (280 ng/g lipid) were still lower than in other world populations. However, the observed increases were not uniform and in some individuals high values (5100 ng/g lipid) were determined. Significant differences were found between the concentrations of DDT and related compounds in breast milk according to parity, with higher concentrations in primiparae than multiparae women. These differences overcome the age effect in DDT accumulation between the two groups and evidence that women transfer a significant proportion of their body burden of DDT and its metabolites to their infants.

Empirical analyses of the influence of diet on human concentrations of persistent organic pollutants: a systematic review of all studies conducted in Spain

BACKGROUND

Numerous studies analyzed concentrations of persistent organic pollutants (POPs) in human samples, and in many types of foods; however, food consumption is less commonly included in studies on the determinants of POP concentrations in humans, and these approaches are rarely integrated with surveys of food intake to estimate the amount and safety of human POP intake from food.

OBJECTIVE

To analyze the main characteristics and findings of all studies conducted in Spain that quantitatively assessed the influence of diet on human concentrations of POPs.

METHODS

Studies published until December 2010 (with no other time restrictions) were identified through Medline/PubMed, ISI-Thomson, ScienceDirect, and SciELO databases.

RESULTS

We identified 25 papers, from 19 different studies. Twelve papers were published in 2009-2010. All studies but one were based on subgroups not representative of the general population, and over half were limited to women. Serum was the most used biological matrix, while p,p'-DDE, HCB and PCBs were the most frequently analyzed compounds. Food intakes were measured with heterogeneous food frequency questionnaires. The most consistent association was between fish consumption and PCBs and HCB, followed by dairy products and PCBs. A few studies observed a relationship between meat and some POPs, whilst intake of vegetables, fruits and cereals was rarely related to POP levels. Only 3 studies did not find any relationship between dietary habits and POP concentrations.

CONCLUSIONS

In spite of methodological heterogeneity, the studies were able to quantify to what extent consumption of foods from animal origin (fish, milk, dairy products and meat) is related to higher body concentrations of POPs. As in a few other countries, in Spain food consumption is increasingly analyzed as a major determinant of human POP intake.

Organochlorine concentrations in breast milk and prevalence of allergic disorders in Japanese women

Persistent organic pollutants have been shown to have immunomodulating effects in humans. However, epidemiological evidence regarding the relationships between organochlorine compound exposure and allergic disorders coming from studies of children has been limited and inconsistent. The current cross-sectional study examined the associations between the concentrations of β-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethylene (DDE), and trans-nonachlordane in breast milk and the prevalence of allergic disorders in 124 adult Japanese women. The definition of wheeze and asthma was based on criteria from the European Community Respiratory Health Survey whereas that of eczema and rhinoconjunctivitis was based on criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age, smoking, family history of allergic disorders, and education. The prevalence values of wheeze, asthma, eczema, and rhinoconjunctivitis in the past 12 months were 9.7%, 4.8%, 13.7%, and 29.8%, respectively. The median concentrations of β-HCH, HCB, p,p'-DDE, and trans-nonachlordane in breast milk were 28.3, 7.0, 71.6, and 23.9 ng g(-1) lipid, respectively (range, 4.5-253, 2.1-14.5, 7.5-362, and 1.8-130 ng g(-1) lipid, respectively). When the exposures were treated as continuous variables, no significant associations were found between concentrations of HCB, β-HCH, p,p'-DDE, or trans-nonachlordane and the prevalence of wheeze, asthma, eczema, or rhinoconjunctivitis. Our results suggest that concentrations of β-HCH, HCB, p,p'-DDE, and trans-nonachlordane in breast milk are not evidently associated with the prevalence of wheeze, asthma, eczema, or rhinoconjunctivitis in young female Japanese adults.

Maternal and childhood asthma: risk factors, interactions, and ramifications

Asthma is emerging as a premier example of a health risk that can largely be molded by the status of the mother and the environmental conditions encountered during sensitive windows of prenatal and early childhood development. While genetic background, allergic status of parents, and predisposition for atopy and inflammation play a role, early-life environmental conditions can completely alter the course of immune and respiratory system development. Environmentally induced alterations that (1) maintain the Th2 bias seen during gestation, (2) block the maturation of innate immune cells and (3) create inflammatory dysfunction in the infant provide the foundation for childhood asthma. No single risk factor can fully explain the increased prevalence of asthma in recent decades but it is assumed that the rapid increase is due to environmental and/or epigenetic changes. Well-established and suspected environmental risk factors cover all categories of early life interactions from diet, exposure to environmental contaminants and drugs, maternal and neonatal infections, hygiene, timing of vaccinations and even the mode of birth delivery. Because asthma is connected to the risk of several comorbid chronic conditions, the benefit of asthma risk reduction and prevention is greater than initially may be apparent. This review discusses strategies to optimize preventative and therapeutic options across life stages.

Effects of prenatal exposure to dioxin-like compounds on allergies and infections during infancy

Dioxin-like compounds are endocrine disruptors. The effects of prenatal exposure to environmental levels of dioxins on immune function during infancy have not been clarified, although dioxins induce immunosuppression in offspring of animals. Moreover, human studies have not assessed the effects of gender- or congener-specific differences. The purpose of this study was to investigate the association between dioxin levels in maternal blood and the risk of infection and allergies in infancy. We examined 364 mothers and their infants enrolled in a Hokkaido Study on Environment and Children's Health between 2002 and 2005 in Sapporo, Japan. Relevant information was collected from a baseline questionnaire during pregnancy, medical records at delivery, and a follow-up questionnaire when the child was 18 months of age that assessed development of allergies and infections in infancy. Dioxin-like compound levels in maternal blood were measured with high-resolution gas chromatography/high-resolution mass spectrometry. Relatively higher levels of polychlorinated dibenzofuran were associated with a significantly increased risk of otitis media, especially among male infants (odds ratio=2.5, 95% confidence interval=1.1-5.9). Relatively higher levels of 2,3,4,7,8-pentachlorodibenzofuran were also associated with a significantly increased risk of otitis media (odds ratio=5.3, 95% confidence interval=1.5-19). However, we observed a weak association between dioxin-like compound levels and allergic symptoms in infancy. At environmental levels, prenatal exposure to dioxin-like compounds may alter immune function and increase the risk of infections in infancy, especially among males. The compound 2,3,4,7,8-pentachlorodibenzofuran may be responsible for this.

The role of epigenetic dysregulation in the epidemic of allergic disease

The epidemic of allergic disease in early life is one of the clearest indicators that the developing immune system is vulnerable to modern environmental changes. A range of environmental exposures epidemiologically associated with allergic disease have been shown to have effects on the foetal immune function in pregnancy, including microbial burden, dietary changes and environmental pollutants. Preliminary studies now suggest that these early effects on immune development may be mediated epigenetically through a variety of processes that collectively modify gene expression and allergic susceptibility and that these effects are potentially heritable across generations. It is also possible that rising rates of maternal allergy, a recognised direct risk factor for infant allergic disease, may be further amplifying the effects of environmental changes. Whilst effective prevention strategies are the ultimate goal in reversing the allergy epidemic, the specific environmental drivers, target genes, and intracellular pathways and mechanisms of early life immune programming are still unclear. It is hoped that identifying genes that are differentially regulated in association with subsequent allergic disease will assist in identifying causal pathways and upstream contributing environmental factors. In this way, epigenetic paradigms are likely to provide valuable insights into how the early environment can be modified to more favourably drive immune development and reverse the allergic epidemic.

Concentrations and determinants of organochlorine levels among pregnant women in Eastern Spain

Persistent organic pollutants (POPs) comprise a large variety of toxic substances with ample distribution. While exposure to these toxins occurs mainly through diet, maternal POP levels may be influenced by certain sociodemographic, environmental, or lifestyle factors. This is important given that these substances may have adverse effects on fetal development. The aim of this study is to examine the sociodemographic, environmental, lifestyle, and dietary determinants of the levels of hexachlorobenzene (HCB), b-hexachlorocyclohexane (b-HCH), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE), and polychlorinated biphenyls (PCB congeners 118, 138, 153, 180) measured in the blood of pregnant women participating in a mother-child cohort study conducted in Valencia (Spain). The study population consisted of 541 pregnant women who formed part of the INMA (Childhood and the Environment) cohort (2004-2006). POP levels were determined in blood taken during the 12th week of pregnancy with the aid of gas chromatography with electron capture detection. Sociodemographic, environmental, and dietary information was obtained from a questionnaire. Multivariate Tobit regression models were constructed in order to assess the association between POP levels and selected covariates. The results showed that all the women had detectable levels of at least one of these compounds while in 43% of the subjects, all eight compounds were detected. The compounds found in the greatest number of women were 4,4'-DDE (100%) and PCBs 153 and 180 (95%). The most important determinants of high POP levels were the mother's age, country of origin, increased body mass index, and number of weeks of breastfeeding after previous pregnancies. With regard to diet, 4,4'-DDT and 4,4'-DDE levels increased with the intake of meat, fruit, and cereal. PCB 153 levels increased with the intake of seafood. The levels of HCB, b-HCH, 4,4'-DDT, and 4,4'-DDE observed in this study were slightly higher than in other studies, whereas the PCB levels were similar.

Exposure to selected endocrine disruptors and neonatal outcome of 86 healthy boys from Nice area (France)

In utero and lactational exposure to endocrine disruptors is thought to be potentially harmful on fetal and infant development. Data of exposure in France is scarce. This is a prospective study with (1) collection of 84 cord bloods (CB) and 69 milks from 86 mothers delivering healthy boys (gestational age >or= 34 weeks) at two maternity wards in Southern France, between 2002 and 2005 and (2) screening for 15 xenobiotics with anti-androgenic and/or estrogenic effects: DDE, 7 PCBs, dibutylphthalate and its metabolite mBP, HCB, lindane, linuron, procymidone and vinclozoline. Correlations were made with delivery and neonatal outcomes. All CB and milks were contaminated by one or more xenobiotics (mainly PCBs, DDE, HCB, and phthalates) with good correlation between CB and milk concentrations. Compared to other geographical areas, exposure was usually in the lower bracket. Milk [PCB180] was associated with lower birth weight. Infant head circumference correlated negatively with [HCB] and positively with [mBP] in CB. There was a similar but not significant trend for birth weight and length. [DDE] in milk was higher in older mothers and in women born in Africa. In utero and lactational exposure is ubiquitous in our area. Contamination of milk with HCB, mBP, and PCB 180 showed weak correlations with infant growth. This snapshot of exposure in an area with no major industry will serve for further monitoring.

The relative influence of diet and serum concentrations of organochlorine compounds on K-ras mutations in exocrine pancreatic cancer

BACKGROUND

In exocrine pancreatic cancer (EPC) mechanistic relationships may exist among some organochlorine compounds (OCs) and mutations in the K-ras oncogene, as well as among the latter and dietary factors.

OBJECTIVE

To analyze (1) the relationship between food intake and serum concentrations of OCs in EPC patients and (2) the relative influence of food and OCs on the frequency of K-ras mutations in EPC.

PATIENTS AND METHODS

Incident cases of EPC were prospectively identified, and interviewed face-to-face during hospital admission (N=135 patients with data on OCs and diet, and N=97 with additional information on K-ras status). OCs were measured by high-resolution gas chromatography with electron-capture detection.

RESULTS

Consumption of milk and other dairy products was positively associated with concentrations of p,p'-DDT, PCB 138 and PCB 153 (log-transformed betas=0.652, 0.588 and 0.317, respectively; all p<0.05). When adjusted by OCs, dairy products were no longer associated with K-ras. By contrast, after adjusting by consumption of dairy products, patients with the highest concentrations of p,p'-DDT and some PCBs remained more likely to have a K-ras-mutated EPC than patients with lower concentrations (OR for upper tertile of PCB 138=5.5, 95% CI: 1.3-23.4).

CONCLUSIONS

Dairy products were a source of OCs. The association between dairy products and K-ras mutations was not independent of OCs. By contrast, the association between OCs and K-ras was not confounded by dairy products. OCs may be more likely to contribute to the occurrence of K-ras mutations than nutrients contained in dairy products.

Insulin-like growth factor-I (IGF-I) serum concentrations in healthy children and adolescents: relationship to level of contamination by DDT-derivative pesticides

CONTEXT

Serum levels of Insulin-like growth factor I (IGF-I) play a critical role in children growth and in the pathogenesis of several diseases. In addition, recent studies suggest that DDT-derivative organochlorine pesticides (OC-DDTs) could influence IGF levels in human beings.

OBJECTIVE AND DESIGN

Because it has been suggested that IGF-I peak levels at puberty could determine IGF-I levels in adulthood, we developed a cross-sectional study of the potential association between serum levels of OC-DDTs and IGF system in 160 serum samples from young people (81 boys and 79 girls) living in the Canary Islands (Spain).

RESULTS

Multivariate tests were used adjusting for confounding variables (age, height, and weight) and stratifying by gender and age: IGF-I serum levels were significantly lower in pre-pubertal male children (6-15years) who showed detectable values of p,p'-DDE, and p,p'-DDD than in pre-pubertal male children with undetectable levels of these OC-DDTs-metabolites (p=0.023 and p=0.049, respectively). In addition, in this multivariate model, a non-linear dose-response curve was observed between Total DDT body burden (sum of the three DDT-derivatives measured: p,p'-DDT, p,p'-DDE, and p,p'-DDD) and IGF-I in pre-pubertal male children (6-15years; p=0.043).

CONCLUSION

These findings suggest that OC-DDTs could modulate the IGF-system in a way that is highly influenced by gender and age. Improvements in our understanding of exogenous determinants of the IGF-system may provide new insights into the role played by environmental contaminants in IGF-related diseases.

Persistent organic pollutants (POPs) in Africa: Egyptian scenario

Persistent organic pollutants (POPs) are organic (carbon-based) compounds that include synthesized substances (pesticides and polychlorinated biphenyls [PCBs]) and other by-product substances generated as a result of human and natural activity (dioxins and furans). Extensive scientific studies have shown that POPs are some of the most dangerous pollutants released into the environment by humans. Great efforts have been made since the early 1960s to enhance chemical management and safety issues. Various conventions have been adopted for this purpose: the Stockholm Convention (SC) is one of the well-known meetings in this context. The SC on POPs (May 2001) focuses on reducing and eliminating releases of 12 POPs coined the 'Dirty Dozen' by the United Nations Environment Program (UNEP). Persistence of such chemicals in soils, air, and water, together with natural processes such as evaporation to the atmosphere and washout by rain and flood, give rise to their ubiquitous distribution in the environment and eventual penetration into food chains and bio-accumulation in humans. Public concern about contamination by POPs increased recently because several of these compounds are identified as hormone disruptors, which can alter normal function of endocrine and reproductive systems in humans and wildlife. African countries are using pesticides, such as dichlorodiphenyltrichloroethane (DDT), lindane, toxaphene, endrin, dieldrin, heptachlor, since more than 50 years for combating agricultural pests and controlling disease vectors, especially malaria. The way in which pesticides are used in Africa caused serious environmental and health problems much more than elsewhere. These problems are represented by accumulation of organochlorine pesticide (OCP) residues in different environmental samples and hosting of at least 50,000 tons of obsolete pesticides, as well as tens of thousands of tons of contaminated soil. Within the framework of the Africa Stockpiles Program (ASP), huge quantities of pesticidal POPs have been completely or partially destroyed in a number of African countries (e.g. Egypt, Namibia, Niger, Senegal, Seychelles, South Africa, Sudan, Tanzania, Uganda, Zambia). At regional level (i.e. African Countries), a strategic plan for monitoring and getting rid of POPs in the continent should be set up and implemented through coordination between all governments. Among issues of top priorities are to find alternative non-combustion technologies for disposing obsolete pesticides, and to use alternative control measures for mosquitoes' management and other vector-borne diseases.

Prenatal and childhood Mediterranean diet and the development of asthma and allergies in children

Objective

To discuss current evidence about the relation between prenatal and childhood Mediterranean diet, and the development of asthma and allergies in children.

Design

Review of the literature.

Setting and results

Four recent studies conducted in Mediterranean countries (Spain, Greece) and one conducted in Mexico evaluated the association between childhood Mediterranean diet and asthma outcomes in children. All of the studies reported beneficial associations between a high level of adherence to the Mediterranean diet during childhood and symptoms of asthma or allergic rhinitis. Individual foods or food groups contributing to the protective effect of Mediterranean diet included fish, fruits, vegetables, legumes, nuts and cereals, while detrimental components included red meat, margarine and junk food intake.

Two studies focused on prenatal Mediterranean diet: the first is a birth cohort in Spain that showed a protective effect of a high adherence to the Mediterranean diet during pregnancy on persistent wheeze, atopic wheeze and atopy at the age of 6·5 years; while the second is a cross-sectional study in Mexico, collecting information more than 6 years after pregnancy, that showed no associations between maternal Mediterranean diet during pregnancy and allergic symptoms in childhood except for current sneezing.

Conclusions

Findings from recent studies suggest that a high level of adherence to the Mediterranean diet early in life protects against the development of asthma and atopy in children. Further studies are needed to better understand the mechanisms of this protective effect, to evaluate the most relevant window of exposure, and to address specific components of diet in relation to disease.

The Pine River statement: human health consequences of DDT use

OBJECTIVES

Dichlorodiphenyltrichloroethane (DDT) was used worldwide until the 1970s, when concerns about its toxic effects, its environmental persistence, and its concentration in the food supply led to use restrictions and prohibitions. In 2001, more than 100 countries signed the Stockholm Convention on Persistent Organic Pollutants (POPs), committing to eliminate the use of 12 POPs of greatest concern. However, DDT use was allowed for disease vector control. In 2006, the World Health Organization and the U.S. Agency for International Development endorsed indoor DDT spraying to control malaria. To better inform current policy, we reviewed epidemiologic studies published from 2003 to 2008 that investigated the human health consequences of DDT and/or DDE (dichlorodiphenyldichloroethylene) exposure.

DATA SOURCES AND EXTRACTION

We conducted a PubMed search in October 2008 and retrieved 494 studies.

DATA SYNTHESIS

Use restrictions have been successful in lowering human exposure to DDT, but blood concentrations of DDT and DDE are high in countries where DDT is currently being used or was more recently restricted. The recent literature shows a growing body of evidence that exposure to DDT and its breakdown product DDE may be associated with adverse health outcomes such as breast cancer, diabetes, decreased semen quality, spontaneous abortion, and impaired neurodevelopment in children.

CONCLUSIONS

Although we provide evidence to suggest that DDT and DDE may pose a risk to human health, we also highlight the lack of knowledge about human exposure and health effects in communities where DDT is currently being sprayed for malaria control. We recommend research to address this gap and to develop safe and effective alternatives to DDT.

Sibship size and prevalence of allergic disorders in Japan: the Ryukyus Child Health Study

A number of epidemiological studies have reported an inverse association between increasing sibship size and allergic disorders. The present cross-sectional study assessed the association between the number of siblings and the prevalence of allergic disorders during the past 12 months in Japanese schoolchildren. Study subjects were 22,750 children aged 6-15 yr in Okinawa. The outcomes were based on diagnostic criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age, gender, maternal age at childbirth, duration of breastfeeding, region of residence, smoking in the household, paternal and maternal history of asthma, atopic eczema, and allergic rhinitis, and paternal and maternal educational level. Significant exposure-response associations were observed between increasing total sibship size and all outcomes under investigation. Having two or more older siblings was significantly inversely related to the prevalence of atopic eczema and allergic rhinoconjunctivitis, but not wheeze or asthma. Having two or more younger siblings was independently associated with a decreased prevalence of atopic eczema, but not wheeze, asthma, or allergic rhinoconjunctivitis. The inverse relationships between sibship size and the prevalence of allergic disorders under study were weakened with advancing age, although the interactions between age groups were not statistically significant. No significant interactions were found in the association of having three or more siblings with allergic disorders between children with a positive or negative parental allergic history. These results are likely to support the in utero programming hypothesis because it is probable that the in utero environment would change with parity, although our observations could not refute the hygiene hypothesis.

Immune cell counts and risks of respiratory infections among infants exposed pre- and postnatally to organochlorine compounds: a prospective study

BACKGROUND

Early-life chemical exposure may influence immune system development, subsequently affecting child health. We investigated immunomodulatory potentials of polychlorinated biphenyls (PCBs) and p,p'-DDE in infants.

METHODS

Prenatal exposure to PCBs and p,p'-DDE was estimated from maternal serum concentrations during pregnancy. Postnatal exposure was calculated from concentrations of the compounds in mother's milk, total number of nursing days, and percentage of full nursing each week during the 3 month nursing period. Number and types of infections among infants were registered by the mothers (N = 190). White blood cell counts (N = 86) and lymphocyte subsets (N = 52) were analyzed in a subgroup of infants at 3 months of age.

RESULTS

Infants with the highest prenatal exposure to PCB congeners CB-28, CB-52 and CB-101 had an increased risk of respiratory infection during the study period. In contrast, the infection odds ratios (ORs) were highest among infants with the lowest prenatal mono-ortho PCB (CB-105, CB-118, CB-156, CB-167) and di-ortho PCB (CB-138, CB-153, CB-180) exposure, and postnatal mono- and di-ortho PCB, and p,p'-DDE exposure. Similar results were found for pre- and postnatal CB-153 exposure, a good marker for total PCB exposure. Altogether, a negative relationship was indicated between infections and total organochlorine compound exposure during the whole pre- and postnatal period. Prenatal exposure to CB-28, CB-52 and CB-101 was positively associated with numbers of lymphocytes and monocytes in infants 3 months after delivery. Prenatal exposure to p,p'-DDE was negatively associated with the percentage of eosinophils. No significant associations were found between PCB and p,p'-DDE exposure and numbers/percentages of lymphocyte subsets, after adjustment for potential confounders.

CONCLUSION

This hypothesis generating study suggests that background exposure to PCBs and p,p'-DDE early in life modulate immune system development. Strong correlations between mono- and di-ortho PCBs, and p,p'-DDE exposures make it difficult to identify the most important contributor to the suggested immunomodulation, and to separate effects due to pre- and postnatal exposure. The suggested PCB and p,p'-DDE modulation of infection risks may have consequences for the health development during childhood, since respiratory infections early in life may be risk factors for asthma and middle ear infections.

Asthma and infectious respiratory disease in relation to residence near hazardous waste sites

The hypothesis that simply living near a hazardous waste site increases risk of exposure to chemicals was tested. Using data from the New York Statewide Planning and Research Cooperative System, which provides information on hospitalized patients, plus information on the location and contents of every known hazardous waste site in New York, the rates of hospitalization for asthma (ICD-9 493), infectious respiratory disease (ICD-9 460-466, 480-487, and 490-491), and Chronic obstructive pulmonary disease (COPD) (ICD-9 490-492 and 494-496) were determined among individuals who lived in (a) zip codes containing or abutting a hazardous waste site with persistent organic pollutants (POPs), (b) zip codes containing or abutting a hazardous waste site, but not one with POPs, and (c) zip codes that do not contain or abut an identified hazardous waste site. After adjustment for MHI, race, gender and urban or rural residence, there was a significantly elevated risk of asthma (rate ratio (RR) = 1.09), infectious respiratory disease (RR = 1.15), and COPD (RR = 1.19) in individuals living in a zip code with a POP waste site, and a significantly elevated risk of asthma (RR = 1.09), infectious respiratory disease (RR = 1.12), and COPD (RR = 1.13) associated with residence in a zip code containing a waste site, but not one with POPs, both relative to residence in a zip code without a waste site. These observations are consistent with the hypothesis that simply living near a hazardous waste site increases risk of exposure to substances that contribute to respiratory disease.

Maternal smoking very early in pregnancy is related to child overweight at age 5-7 y

BACKGROUND

Despite being associated with lower birth weight, maternal smoking in the last 2 trimesters of pregnancy has been associated with increased risk of offspring overweight in several studies. To date, only one study has examined whether smoking in the first trimester only, which is not associated with birth weight, is also associated with childhood overweight.

OBJECTIVE

This study uses prospective data to examine associations between maternal smoking in the first compared with later trimesters of pregnancy and child overweight at age 5-7 y.

DESIGN

Data from a prospective cohort of 369 Spanish children born in 1997-1998 were used. Logistic regression was used to estimate associations between maternal smoking during different time periods and odds of child overweight later in life.

RESULTS

Maternal smoking during the first trimester was more strongly associated with overweight (adjusted odds ratio: 2.65; 95% CI: 1.26, 5.54) than smoking later in pregnancy (1.88, 0.85, 4.15). Smoking limited to the first month of pregnancy was also associated with child overweight. Neither paternal smoking nor maternal smoking before or after pregnancy was associated with child overweight. Significant interactions with breastfeeding duration indicated that first-trimester smoking was associated with overweight only among children breastfed for <6 mo, suggesting prolonged breastfeeding may help to counter adverse effects of smoking in early pregnancy.

CONCLUSIONS

These data suggest maternal smoking very early in pregnancy may increase risk of later overweight in children and provide further support for promoting smoking cessation before rather than during early pregnancy. Further studies are needed to confirm these results.

Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants

This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.

Monitoring concentrations of persistent organic pollutants in the general population: the international experience

Assessing the adverse effects on human health of persistent organic pollutants (POPs) and the impact of policies aiming to reduce human exposure to POPs warrants monitoring body concentrations of POPs in representative samples of subjects. While numerous ad hoc studies are being conducted to understand POPs effects, only a few countries are conducting nationwide surveillance programs of human concentrations of POPs, and even less countries do so in representative samples of the general population. We tried to identify all studies worldwide that analyzed the distribution of concentrations of POPs in a representative sample of the general population, and we synthesized the studies' main characteristics, as design, population, and chemicals analyzed. The most comprehensive studies are the National Reports on Human Exposure to Environmental Chemicals (USA), the German Environmental Survey, and the Arctic Monitoring and Assessment Programme. Population-wide studies exist as well in New Zealand, Australia, Japan, Flanders (Belgium) and the Canary Islands (Spain). Most such studies are linked with health surveys, which is a highly-relevant additional strength. Only the German and Flemish studies analyzed POPs by educational level, while studies in the USA offer results by ethnic group. The full distribution of POPs concentrations is unknown in many countries. Knowledge gaps include also the interplay of age, gender, period and cohort effects on the prevalence of exposures observed by cross-sectional surveys. Local and global efforts to minimize POPs contamination, like the Stockholm convention, warrant nationwide monitoring of concentrations of POPs in representative samples of the general population. Results of this review show how such studies may be developed and used.

Genotoxicity of the organochlorine pesticides 1,1-dichloro-2,2- bis(p-chlorophenyl)ethylene (DDE) and hexachlorobenzene (HCB) in cultured human lymphocytes

The possible genotoxic potential of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), which is a metabolite of dichlorobiphenyltrichloroetane (DDT), and hexachlorobenzene (HCB), which are organochlorine pesticides have been evaluated in vitro by using human lymphocytes as test system. Genetic damage was determined by scoring the frequency of micronuclei (MN) in primary lymphocyte cultures obtained from different donors. The results indicated that, under the experimental conditions used, the DDT metabolite DDE was able to induce significant increases in the frequency of micronucleated cells, which indicate a certain clastogenic and/or aneugenic potential. DDE was tested in the range of 10-80 mM, but the only concentration producing a significant genotoxic effect was 80 mM. On the other hand, HCB was unable to induce a significant increase in the MN frequency in the range of concentrations assayed, from 0.005 to 0.1mM. The selected concentrations of DDE and HCB were chosen according to their toxicity in cell blood cultures; higher concentrations reduced significantly cell proliferation and produced a low frequency of binucleated cells. In conclusion, the results indicate that a genotoxic risk is associated with the exposure to DDE at concentrations 80 mM and above.

Rapid decline of persistent organochlorine pollutants in serum among young Swedish males

To investigate a possible time trend in serum concentrations of persistent organochlorine pollutants (POPs), representative samples of the young (median age 18 years) Swedish male population were investigated in the years 2000 and 2004. Due to their low age, these men were assumed not to have reached steady state of body burdens of POPs, why their serum concentrations were considered to represent ongoing dietary exposure. Serum concentrations of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethylene (p,p'-DDE), two biomarkers of exposure to POPs, were available for 274 and 223 men, respectively, in 2000 and for 200 men in 2004. The percentage of men with CB-153 or p,p'-DDE below the limit of detection (LOD) was significantly higher in 2004 than in 2000 (30% vs. none, p < 0.001 for CB-153 and 65% vs. 6%, p < 0.001 for p,p'-DDE). Moreover, the median serum concentration of CB-153 decreased from 66 ng g(-1) lipid to 19 ng g(-1), corresponding to a yearly decrease of about 26%. The analogous analysis was not done for p,p'-DDE since the median serum concentration in 2004 was below the LOD.

On the role of breastfeeding in health promotion and the prevention of allergic diseases

Based on animal models, we specify the major role of different bioactive milk components known to participate significantly in neonatal health promotion and in protection against a large number of infectious diseases and the development of allergies and asthma.

Chlorinated organic pesticides in marketed food: Barcelona, 2001-06

This paper reports concentration levels of 22 chlorinated organic compounds (both primary compounds and metabolites) in food marketed in the city of Barcelona (Catalonia, Spain) in 2001-06. Samples included meat products, fish and seafood, eggs, milk and dairy, vegetal oils, cereal products and derivates, vegetables, fresh fruits, dry fruits, spices, formula and baby food, tea and wine. Levels of chlorinated organic compounds were determined by gas chromatography with selective detectors: electron capture (ECD), flame photometric (FPD) and confirmation with mass-spectrometry. Chlorinated organic pesticides were detected in 7 of the 1,484 samples analyzed in the 2001-06 period (0.5%): 1 dairy product, 1 fruit, 1 olive oil and 4 vegetables. Specific pesticides detected are lindane and endosulfan alpha, beta or sulphate. A decrease in both the proportion of samples with detectable residues and in the variety of chlorinated pesticides found is visible when comparing these results with those of the previous 1989-2000 period. These results suggest the gradual disappearance of regulated chlorinated organic pesticides as a consequence of the growing worldwide implementation of current regulatory agreements.

[Incidence of asthma and risk factors in a cohort of schoolchildren aged from 6-7 years old to 14-15 years old in Castellón (Spain) following the International Study of Asthma and Allergies in Childhood (ISAAC)]

BACKGROUND AND OBJECTIVE

To estimate the incidence of asthma in schoolchildren from 6-7 years old to 14-15 years old and associated risk factors.

POPULATION AND METHOD

A cohort study, with the ISAAC phases I and III in 1994 and 2002, respectively, was carried out in Castellón, and the nearby towns Vila-real, Almassora, Benicàssim, El Grau de Castelló, Borriol, and L'Alcora. In 1992, 3,607 schoolchildren aged 6-7 years old took part, of whom 1,805 were again studied in 2002, at the age of 14-15. New cases of asthma were defined following the ISAAC questionnaire. Poisson regression was used in the analysis of asthma risk factors.

RESULTS

Participation was 50.0%. The cumulative incidence of asthma was 6.4% during the 8 years of study, 108 new cases of 1,698 schoolchildren free of asthma at beginning. Incidence was greater in boys than girls, and in 14-year old teenagers compared to 15-year olds, although differences were not significant. Risk factors associated with the incidence of asthma were: family history of asthma, history of allergic rhinitis, history of bronchitis and upper-middle compared to lower social class.

CONCLUSIONS

A low incidence of asthma was found in schoolchildren from Castellón, Spain, in comparison with other cohort studies. Estimated risk factors were generally in accordance with incidence studies.

Serum levels of insulin-like growth factor-I in relation to organochlorine pesticides exposure

CONTEXT

Insulin-like growth factor 1 (IGF-I) and organochlorine pesticides (OCs) have been involved in the pathogenesis of several diseases like cancer, diabetes and growth disorders.

OBJECTIVE AND DESIGN

The potential relationship between the serum levels of various OCs and serum IGF-I was investigated in adults (176 men and 247 women) from a representative sample of the general population of the Canary Islands (Spain).

RESULTS

After adjustment for potential confounders, which include body mass index, age, and IGF-binding protein-3 (IGFBP-3), IGF-I levels were significantly lower in the 247 women who showed detectable levels of p,p'-DDD (a DDT-metabolite) than in women who presented non-detectable levels of this pesticide (p=0.030), specially in 36-50 years old women. A similar negative relationship was also found between IGF-I and aldrin (a non-DDT-derivative) in women (p=0.049). In the group of 176 men, aldrin seemed to exert a similar negative effect on IGF-I (p=0.046) and this effect was clearly significant in the oldest group (51-65 years) (p=0.009). A non-linear dose-response curve was observed between Total Cyclodienes Body Burden (Total Cyclodienes; sum of aldrin, dieldrin and endrin) and IGF-I in men (p=0.024). These findings suggest that OCs could modulate the IGF-system in a way that is highly influenced by gender, age and by chemical or combination of chemicals implicated. Such circumstances may contribute to the development of a number of diseases related to IGF-I and should be taken into account in public health decisions.

Association of thyroid hormone concentrations with levels of organochlorine compounds in cord blood of neonates

BACKGROUND

Thyroid hormones are important regulators of brain development. During critical periods of development, even transient disorders in thyroid hormone availability may lead to profound neurologic impairment. Animal experiments have shown that certain environmental pollutants, including heavy metals and organochlorine compounds such as polychlorinated biphenyls (PCBs) and dioxins, can interfere with thyroid hormone homeostasis. Whether these contaminants can affect circulating levels of thyroid hormones in humans is unclear, however, because the results of available studies are inconsistent.

OBJECTIVES

The aim of the present study is to examine the possible relationships between concentrations of environmental pollutants and thyroid hormone levels in human umbilical cord blood.

METHODS

We measured concentrations of environmental pollutants [including selected PCBs, dioxin-like compounds, hexachlorobenzene, p,p'-DDE (dichlorodiphenyldichloroethylene), cadmium, lead] and thyroid hormones in the cord blood of 198 neonates.

RESULTS

A statistically significant inverse relationship between concentrations of organochlorine compounds and levels of both free triiodothyronine (fT3) and free thyroxine (fT4), but not thyroid-stimulating hormone, was observed. We found no association between concentrations of heavy metals and thyroid hormone levels.

CONCLUSIONS

Our results suggest that environmental chemicals may affect the thyroid system of human neonates. Although the differences in fT3 and fT4 levels associated with the organochlorine compounds were within the normal range, the observed interferences may still have detrimental effects on the neurologic development of the individual children, given the importance of thyroid hormones in brain development.

Environmental factors and allergic disorders

Despite numerous studies on possible associations between environmental exposure and allergic disorders, any conclusions made remain a matter of controversy. We conducted a review of evidence in relation to environmental and nutritional determinants and wheeze, asthma, atopic dermatitis, and allergic rhinitis. Identified were 263 articles for analysis after consideration of 1093 papers that were published since 2000 and selected by electronic search of the PubMed database using keywords relevant to epidemiological studies. Most were cross-sectional and case-control studies. Several prospective cohort studies revealed inconsistent associations between various environmental factors and the risk of any allergic disorder. Therefore, the evidence was inadequate to infer the presence or absence of a causal relationship between various environmental exposures and allergic diseases. However, evidence is suggestive of positive associations of allergies with heredity. Because almost all the studies were performed in Western countries, the application of these findings to people in other countries, including Japan, may not be appropriate. Further epidemiological information gained from population-based prospective cohort studies, in particular among Japanese together with other Asians, is needed to assess causal relationships between various environmental factors and allergic diseases.

The influence of lipid and lifestyle factors upon correlations between highly prevalent organochlorine compounds in patients with exocrine pancreatic cancer

We aimed to analyse the influence of cholesterol and triglycerides, and of tobacco, coffee and alcohol consumption upon correlations between serum concentrations of organochlorine compounds (OCs) in patients with exocrine pancreatic cancer (EPC). Incident cases of EPC diagnosed in eastern Spain were prospectively identified (N=144). OCs were analysed by high-resolution gas chromatography with electron-capture detection. A strong correlation was observed between hexachlorobenzene (HCB) and beta-hexachlorocyclohexane (beta-HCH) (Spearman's rho=0.758). beta-HCH showed rho>0.4 with p,p'-DDT, p,p'-DDE, PCB138 and PCB153 (all p<0.001). Some correlations among compounds were slightly affected by tobacco, coffee or alcohol consumption. We observed a striking diversity of correlation patterns by strata of cholesterol and triglycerides. Most correlations were higher in the lowest category of triglycerides than in the lowest category of cholesterol. Most coefficients above 0.7 were seen in the lowest category of triglycerides (e.g., OC pairs p,p'-DDT and HCB, p,p'-DDT and beta-HCH, p,p'-DDE and beta-HCH, or HCB and beta-HCH). Correlations among OCs may be stronger when concentrations of triglycerides are low than when they are high. This is compatible with a dilution in the early phases of cancer and with a concentration effect as triglycerides become lower in the advanced phases of the disease.

Seasonal birth patterns in myositis subgroups suggest an etiologic role of early environmental exposures

OBJECTIVE

To evaluate whether seasonal early environmental exposures might influence later development of autoimmune disease, by assessing distributions of birth dates in groups of patients with idiopathic inflammatory myopathies (IIMs).

METHODS

We assessed birth patterns in groups of patients with juvenile-onset IIM (n = 307) and controls (n = 3,942) who were born between 1970 and 1999, and in groups of patients with adult-onset IIM (n = 668) and controls (n = 6,991) who were born between 1903 and 1982. Birth dates were analyzed as circular data. Seasonal clustering was assessed by the Rayleigh test, and differences between groups by a rank-based uniform scores test.

RESULTS

The overall birth distributions among patients with juvenile IIM and among patients with adult IIM did not differ significantly from those among juvenile and adult controls, respectively. Some subgroups of patients with juvenile IIM had seasonal birth distributions. Hispanic patients with juvenile-onset IIM had a seasonal birth pattern (mean birth date October 16) significantly different from that of Hispanic controls (P = 0.002), who had a uniform birth distribution, and from that of non-Hispanic patients with juvenile-onset IIM (P < 0.001), who had a mean birth date of May 2. Juvenile dermatomyositis patients with p155 autoantibody had a birth distribution that differed significantly from that of p155 antibody-negative juvenile dermatomyositis patients (P = 0.003). Juvenile IIM patients with the HLA risk factor allele DRB1*0301 had a birth distribution significantly different from those without the allele (P = 0.021). Similar results were observed for juvenile and adult IIM patients with the linked allele DQA1*0501, versus juvenile and adult IIM patients without DQA1*0501, respectively. No significant patterns in birth season were found in other subgroups.

CONCLUSION

Birth distributions appear to have stronger seasonality in juvenile than in adult IIM subgroups, suggesting greater influence of perinatal exposures on childhood-onset illness. Seasonal early-life exposures may influence the onset of some autoimmune diseases later in life.

Early exposure to dichlorodiphenyldichloroethylene, breastfeeding and asthma at age six

Our aims were to assess association of dichlorodiphenyldichloroethylene (DDE) with childhood asthma measured up to age 6 and the effect of DDE on the protective effect of breastfeeding on asthma. In addition, we attempted to assess the relevant time-window of DDE exposure (i.e. at birth or at 4 years). All women presenting for antenatal care in Menorca, Spain over a 12-month period beginning in mid-1997 were invited to take part in a longitudinal study that included a yearly visit. Four hundred eighty-two children were enrolled and 462 provided complete outcome data after 6.5 years of follow-up. Organochlorine compounds were measured in cord serum of 402 (83%) infants and in blood samples of 285 children aged 4. We defined asthma as the presence of wheezing at age 6 and during any preceding year or doctor-diagnosed asthma, and used skin prick test at age 6 to determine atopic status. Results At birth and 4 years of age, all children had detectable levels of DDE (median 1 ng/mL and 0.8 ng/mL, respectively). From birth to age 4, the mean DDE level among children with artificial feeding decreased by 72%, while among breastfed children it increased by 53%. Diagnosed asthma and persistent wheezing were associated with DDE at birth [odds ratio (OR) for an increase in 1 ng/mL, OR=1.18, 95% confidence interval (95% CI)=1.01-1.39 and OR=1.13, 95% CI=0.98-1.30, respectively], but not with DDE at 4 years. Neither breastfeeding nor atopy modified these associations (P>0.3). Breastfeeding protected against diagnosed asthma (OR=0.33, 95% CI=0.08-0.87) and wheezing (OR=0.53, 95% CI=0.34-0.82) in children with low and high DDE levels at birth. Conclusion In a community without known dichlorodiphenyltrichloroethane environmental releases, this study strengthens the evidence for an effect of DDE on asthma by measuring the disease at age 6 and does not support the hypothesis that DDE modifies the protective effect of breastfeeding on asthma.

Occupational and indoor air exposure to persistent organic pollutants: a review of passive sampling techniques and needs

Exposure to persistent organic pollutants (POPs) and related compounds such as PCBs, brominated flame retardants, organochlorine pesticides and PAHs is regarded as an important environmental risk factor for humans. Recently concerns about POPs resulted in the international protocol called the Stockholm Convention on POPs. Air quality standards (indoor, outdoor and occupational) for PAHs and other POPs will also be applied in the EU in the future. This will bring requirements for monitoring, to check for compliance and to reduce human exposures to POPs. This can occur from point sources and in various microenvironments, indoors, outdoors and in workplaces. Monitoring can be undertaken either by an active (pumped) method or using a passive (diffusive) air sampling (PAS) device. To date, PAS for POPs have mainly been used as integrating (long-term) samplers for ambient (outdoor) air. However, there are several reasons to develop PAS for monitoring of POPs in occupational and indoor environments. We discuss the potential advantages, limitations and developments needed, so that PAS can be used reliably and routinely indoors and in occupational settings for POPs.

Maternal fish intake during pregnancy and atopy and asthma in infancy

BACKGROUND

There is growing evidence that n-3 fatty acids have anti-inflammatory properties and may modulate immune response. Dietary intake of these nutrients during pregnancy could play a role in the risk of asthma and atopy in the offspring.

METHODS

Using data from a cohort of women (n=462) enrolled during pregnancy and whose offspring were followed up to 6 years, we evaluated the impact of fish consumption during pregnancy on the incidence of atopy and asthma. Dietary intake was assessed by food frequency questionnaire (42 items) applied by an interviewer.

RESULTS

Thirty-four percent of infants had a medical diagnosis of eczema at age 1 year, 14.3% of the children were atopic [based on skin prick test (SPT) at 6 years], and 5.7% had atopic wheeze at age 6 years. After adjusting for potential confounding factors, fish intake during pregnancy was protective against the risk of eczema at age 1 year, a positive SPT for house dust mite at age 6 years and atopic wheeze at age 6 years [odds ratio (OR)=0.73 95% confidence interval (CI) 0.55-0.98, OR=0.68, 95% CI 0.46-1.01 and OR=0.55, 95% CI 0.31-0.96, respectively]. For an increase in fish intake from once per week to 2.5 times per week, the risk of eczema at age 1 year decreased by 37%, and the risk of positive SPT at age 6 years by 35%. Stratification by breastfeeding showed that fish intake was significantly related to a decrease risk in persistent wheeze among non-breastfed children (P for interaction<0.05). No protective effect was observed among breastfed children.

CONCLUSION

Our data suggest a protective effect of fish intake during pregnancy on the risk of atopy-related outcomes.

The early-life origins of asthma

PURPOSE OF REVIEW

Inflammatory mediators produced from activated mast cells and T helper type 2 cells drive allergic inflammation. The pathways required for mast and T helper type 2 cell activation and the effects of their products are being defined in order to identify new therapeutics. We focus on recent findings on the chief inducer of mast cell activation, the IgE receptor-signaling cascade, and the development of new inhibitors of this pathway. We also summarize work that examines the molecular mechanisms utilized by the interleukin IL-4/13 receptors and characterizes therapeutic compounds that target these pathways.

RECENT FINDINGS

The tyrosine kinases Lyn, Fyn and Syk have complex roles in IgE receptor signaling. Biochemical analysis and gene expression profiling have shed light on both the positive and negative functions of these proteins and establish additional connections with downstream pathways. Syk inhibitors were identified that may prove useful as antiinflammatory agents. Progress has been made in characterizing how IL-4/13 interact with their cognate receptors that will aid in the design of inhibitors of these interactions.

SUMMARY

Recent studies have advanced our understanding of how the IgE receptor and IL-4/13 receptors function. This new knowledge may lead to the development of novel and highly specific inhibitors of allergic inflammation.

Health effects of common home, lawn, and garden pesticides

Children encounter pesticide products and their residues where they live and play and in the food supply. Pesticide exposure affects pediatric health both acutely and chronically; effects range from mild and subtle to severe. Pediatricians play an important role in identifying and reducing significant pesticide exposure in their patients by taking an exposure history to clarify the extent and types of exposures that may have occurred during acute care and preventive care visits. Developing knowledge about the toxicity of various chemicals, identifying reliable resources for pesticide information, and providing a common-sense approach toward recommending the safest practical alternatives is necessary.

In utero exposure to background concentrations of DDT and cognitive functioning among preschoolers

p,p'-DDT (bis[p-chlorophenyl]-1,1,1-trichloroethane) is a persistent organochlorine compound that has been used worldwide as an insecticide. The authors evaluated the association of cord serum levels of DDT and its metabolite, 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (DDE), with neurodevelopment at age 4 years. Two birth cohorts in Ribera d'Ebre and Menorca (Spain) were recruited between 1997 and 1999 (n = 475). Infants were assessed at age 4 years by using the McCarthy Scales of Children's Abilities. Organochlorine compounds were measured in cord serum. Children's diet and parental sociodemographic information was obtained through questionnaire. Results showed that DDT cord serum concentration at birth was inversely associated with verbal, memory, quantitative, and perceptual-performance skills at age 4 years. Children whose DDT concentrations in cord serum were >0.20 ng/ml had mean decreases of 7.86 (standard error, 3.21) points in the verbal scale and 10.86 (standard error, 4.33) points in the memory scale when compared with children whose concentrations were <0.05 ng/ml. These associations were stronger among girls. Prenatal exposure to background, low-level concentrations of DDT was associated with a decrease in preschoolers' cognitive skills. These results should be considered when evaluating the risk and benefits of spraying DDT during antimalaria and other disease-vector campaigns.

DDE-induced apoptosis in children exposed to the DDT metabolite

In a preliminary study in children we found a weak positive association between the frequency of apoptosis and the exposure to DDT and DDE (a DDT metabolite). In order to verify this information, more studies were needed with an increased number of children. Thus, the aim of the present work was to see if DDT and its metabolites were able to induce apoptosis of PBMC in exposed children. We performed a study in children living in three communities located in southern Mexico. During the year 2003, we studied a total of 61 healthy children; and during the year 2004, 57 children from the same communities were assessed. Apoptosis frequencies in PBMC in these children ranged from 0.10% to 8.30% during 2003 and from 0.12% to 16.20% during 2004, and although we detected exposure to DDT, DDD and DDE, significant association with apoptosis frequencies was found only with DDE blood levels (p=0.010 and 0.040 for 2003 and 2004 respectively). DNA damage and oxidative DNA damage were also studied in 2004 using the comet assay. The association between exposure to DDT or DDE and DNA damage was significant (p=0.004 and p=0.005 respectively), but the association between DDT or DDE and oxidative DNA damage and that of oxidative damage and apoptosis were not significant. Taking into account that DDE is the most persistent metabolite, it would be important to assess the effects of this DDE-induced apoptosis of PBCM in children living in areas where DDT was sprayed.

Human Milk, Environmental Toxins and Pollution of Our Infants: Disturbing Findings during the First Six Months of Life

BACKGROUND

Toxic organochlorine compounds (OC) are transmitted from mother to infant during lactation. OC are ingested by and stored in their offspring. Different harmful effects later in life have been attributed to the body pollution with these OC, although these findings are still discussed in an argumentative manner, since first other investigators could demonstrate beneficial effects of breast-feeding despite elevated OC concentrations, and second the benefits of breast-feeding are an unchallenged fact, especially in those countries, where infant formulas are not available. It was the aim of the present study to determine the lactational uptake of different OC (polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), and DDE) in breast-fed vs. bottle-fed infants up to six months of age.

METHODS

With the written informed consent of the parents, blood samples were taken from each ten breast-fed and bottle-fed infants, respectively. The specimens were immediately centrifuged, and serum was stored in glass tubes without an anticoagulant up to analysis. Three higher-chlorinated PCB congeners (IUPAC Nos. 138, 153, and 180), HCB, and DDE, the main metabolite of DDT in mammals, were determined with capillary gas chromatography with electron capture detection. In addition, reliability was tested with gas chromatography-mass spectrometry. Possible correlations of OC with personal data were tested with a standard multivariate regression model. Differences between study groups were tested on mean differences with Wilcoxons test for independent samples.

RESULTS

We could demonstrate that breast-fed infants have significantly (p<0.0001) elevated serum concentrations of all OC as early as at the age of six weeks (90%), which over and above nearly doubled further until the age of six months. (Median (μg/L); A=six weeks; B=six months): PCB 138, A: 0.40 vs. 0.09; B: 0.72 vs. 0.07; PCB 153, A: 0.57 vs. 0.11; B: 0.99 vs. 0.09; PCB 180, A: 0.33 vs. 0.04; B: 0.58 vs. 0.02; PCB (sum of the three PCB congeners), A: 1.19 vs. 0.29; B: 2.28 vs. 0.18; HCB, A: 0.13 vs. 0.04; B: 0.43 vs. 0.07; DDE, A: 1.05 vs. 0.18; B: 1.90 vs. 0.19.

CONCLUSIONS

The discussion about the benefits of breast-feeding should be reconsidered again, with special emphasis on the question, whether the recommendations for breast-feeding can unreservedly be maintained for the future throughout the world, especially in face of the availability of infant formulas in industrialized vs. Third World countries, respectively.