Polycyclic aromatic hydrocarbons in residential dust: sources of variability.

BackgroundThere is interest in using residential dust to estimate human exposure to environmental contaminants.ObjectivesWe aimed to characterize the sources of variability for polycyclic aromatic hydrocarbons (PAHs) in residential dust and provide guidance for investigators who plan to use residential dust to assess exposure to PAHs.MethodsWe collected repeat dust samples from 293 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 through 2007 and during 2010) using household vacuum cleaners, and measured 12 PAHs using gas chromatography-mass spectrometry. We used a random- and a mixed-effects model for each PAH to apportion observed variance into four components and to identify sources of variability.ResultsMedian concentrations for individual PAHs ranged from 10 to 190 ng/g of dust. For each PAH, total variance was apportioned into regional variability (1-9%), intraregional between-household variability (24-48%), within-household variability over time (41-57%), and within-sample analytical variability (2-33%). Regional differences in PAH dust levels were associated with estimated ambient air concentrations of PAH. Intraregional differences between households were associated with the residential construction date and the smoking habits of residents. For some PAHs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Within-household differences between sampling rounds were largest when the interval between dust sample collections was at least 6 years in duration.ConclusionsOur findings indicate that it may be feasible to use residential dust for retrospective assessment of PAH exposures in studies of health effects

Influence de divers facteurs écologiques sur la bioaccumulation d'éléments métalliques (Cd, Cu, Pb, Zn) chez de jeunes palourdes (Ruditapes philippinarum) au cours du prégrossissement en nourricerie

La bioaccumulation des métaux chez les mollusques peut être une conséquence de la désorption des éléments métalliques fixés sur les particules inertes ou vivantes en suspension dans l'eau qui leur servent de nourriture. Les meilleures expériences réalisées jusqu'ici semblent indiquer que les matières en suspension ont un rôle mineur dans la contamination des mollusques. Mais quelles que soient les précautions prises, les expériences ne simulent jamais parfaitement les phénomènes naturels. Aussi, nous avons choisi de reprendre cette question à l'aide d'une expérience en grand volume où le nombre de paramètres contrôlés est restreint mais où les organismes sont dans des conditions aussi proches que possible de la réalité.Au cours d'un prégrossissement expérimental, les jeunes palourdes reçoivent des quantités variables contrôlées de nourriture phytoplanctonique. La fourniture d'une nourriture plus abondante a pour conséquence d'augmenter les quantités de cuivre et de zinc et au contraire de diminuer celles de plomb contenues dans chaque individu. Elle entraîne également une diminution des concentrations en cadmium et plomb traduisant une « dilution biologique » de ces métaux. L'augmentation de la densité de la population expérimentale a un effet négatif sur les quantités de cuivre et de zinc contenues dans les individus. A âge identique, les individus les plus grands présentent des concentrations plus faibles en cuivre et zinc et plus élevées en cadmium et plomb.L'utilisation des eaux marines souterraines présente deux avantages: une production algale intense à un coût économique négligeable et la possibilité par échange thermique de réchauffer en hiver les eaux marines naturelles et ainsi de maintenir une croissance des mollusques toute l'année. L'emploi des eaux de forage n'entraîne aucun effet néfaste dans les phénomènes de bioaccumulation des métaux, du moins pour ceux étudiés ici : cadmium, cuivre, plomb et zinc.Metal bioaccumulation in bivalves may occur as a consequence of the ingestion of inert or living particles with fixed trace elements. The best experiments like those carried out by BORCHARDT (1983, 1985) concerning Cd in mussels have shown that the role suspended matter plays in the contamination of molluscs is insignificant. But, however reliable the experimental methodologies, laboratory conditions never reproduce perfectly natural phenomena. We planned therefore to restudy the problem by using a largescale experiment where the procedure was characterized by a restricted number of controlled parameters and the organisms as close as possible to the real conditions.During an experimental nursing of young carpet shells, we assessed the influence of various controlled quantifies of phytoplankton and of experimental population density on the transfer of metal from their environment to molluscs.Carpet-shell brood (Ruditapes philippinarum) was distributed in several cylindrical containers the bottom of which consisted in a sieve. Food and seawater were renewed continuously by means of an ascending current (BAUD et BACHER, 1990). Nursing assays were carried out during summer over a period of 74 days. Eight groups of carpet shells were constituted according to food supplies (0, lx, 2x and 4x of Skeletonema costatum grown upon underground seawater plus natural phytoplankton) and population density (25 000 or 50 000 individuals per experimental container). Young molluscs were fed according to a cycle of 3 h-feeding periods and 2 h-periods with no food alternately. The average concentrations of algal cells in mollusc breeding seawater were 17.5, 35 and 70.103 cells/L. This seawater was renewed at a flow rate of 3 m3/h.At the end of the nursing period, molluscs exposed to different experimental conditions were separated by using sieves of different mesh-size (6, 8 and 10 mm). Young carpet shells were purged for 36 h in order to limit the overvaluation of bioaccumulated metal levels due to ingested matter (AMIARD-TRIQUET et al., 1984; KENNEDY, 1986). In each experimental and size-related categories, 90 individuals were sampled and divided into 3 groups of 30 specimens.In these groups, soft tissues were separated from the shells and oven-dried at 80 °C for 48 h. The dry samples were powdered and three aliquot parts of about 100 mg each were digested with 1 ml of concentrated nitric acid (HNO3, Suprapur) at 95 °C for 1 h. Then the trace element analyses were performed in this solution diluted with deionized water by dame (Zn) or by flameless (Cd, Cu, Pb) atomic absorption spectrophotometry using the Zeeman effect (AMIARD et al., 1987).The influence of both food supplies and experimental population density on the dry weight of soil tissues of young carpet shells, their metal concentration and body burdens were examined by means of multi-linear regression analysis.Increasing body burdens of Cu (4) and Zn (5) and decreasing body burden of Pb (3), corresponded to more abundant food supplies. The increase of phytoplankton supplies induced a decrease of Cd (6) and Pb (7) concentrations as a consequence of a « biological dilution » of these metals. Increasing density induced a depletion of Cu (4) and Zn (5) body burdens. Among individuals of the same age, the biggest ones exhibited the lowest concentrations of Cu and Zn (8 and 9) and the highest concentrations of Cd and Pb (6 and 7).Increased food supplies induce a biological dilution of Cd and Pb in young carpet-shells. These results are in agreement with previous data concerning Cd, Cu, Pb and Zn in different species (MACKAY et al., 1975; BOYDEN, 1971; PHELPS et al., 1985; BERTHET, 1986). Thus front a sanitary point of view, the use of ground seawater for algal culture is not a risk since metal concentrations in molluscs are not enhanced

Genetic variants in ARID5B and CEBPE are childhood ALL susceptibility loci in Hispanics.

Recent genome-wide studies conducted in European Whites have identified novel susceptibility genes for childhood acute lymphoblastic leukemia (ALL). We sought to examine whether these loci are susceptibility genes among Hispanics, whose reported incidence of childhood ALL is the highest of all ethnic groups in California, and whether their effects differ between Hispanics and non-Hispanic Whites (NHWs). We genotyped 13 variants in these genes among 706 Hispanic (300 cases, 406 controls) and 594 NHW (225 cases, 369 controls) participants in a matched population-based case-control study in California. We found significant associations for the five studied ARID5B variants in both Hispanics (p values of 1.0 × 10(-9) to 0.004) and NHWs (p values of 2.2 × 10(-6) to 0.018). Risk estimates were in the same direction in both groups (ORs of 1.53-1.99 and 1.37-1.84, respectively) and strengthened when restricted to B-cell precursor high-hyperdiploid ALL (>50 chromosomes; ORs of 2.21-3.22 and 1.67-2.71, respectively). Similar results were observed for the single CEBPE variant. Hispanics and NHWs exhibited different susceptibility loci at CDKN2A. Although IKZF1 loci showed significant susceptibility effects among NHWs (p < 1 × 10(-5)), their effects among Hispanics were in the same direction but nonsignificant, despite similar minor allele frequencies. Future studies should examine whether the observed effects vary by environmental, immunological, or lifestyle factors

Contaminação de aflatoxinas em castanha-do-brasil com casca em sistemas extrativista e de plantio.

Diante de problemas de contaminação por aflatoxinas enfrentados na cadeia produtiva da castanha-do-brasil, o objetivo deste trabalho foi estudar o teor de aflatoxinas em castanhas com casca em diferentes etapas dos sistemas de produção: extrativista e de plantio. A produção extrativista consiste na coleta de ouriços recém caídos das árvores e permanecidos no solo por vários dias, empilhamento na floresta, abertura e seleção de castanhas com casca, seguida de armazenamento/secagem sob ventilação durante vários meses. Contudo, no sistema de plantio somente os ouriços com menos de 5 dias no solo são coletados, em seguida são desinfectados com hipoclorito de sódio a 1% e armazenados sob ventilação até abertura e seleção das castanhas com casca. Sessenta amostras de castanha-do-brasil com casca foram coletadas diretamente ou após abertura dos ouriços na região amazônica do Brasil, provenientes da produção extrativista no Acre e do sistema de plantio no Amazonas. As aflatoxinas (B1, B2, G1, G2) foram determinadas por Cromatografia Líquida de Alto Desempenho com detector de fluorescência bem como a atividade de água (aw) nas castanhas descascadas. Nas etapas do sistema extrativista na floresta, dos 33 ouriços coletados, castanhas provenientes de um ouriço com menos de 5 dias de contato com o solo e um ouriço empilhado durante 15 dias apresentaram contaminação por AFB1 inferior a 0,1 µg/kg de matéria fresca (MF). Entretanto o nível de AFB1 variou de 0,6 a 4,4 µg/kg de MF em 3 ouriços com mais de 30 dias em contato com o solo, mais susceptíveis a serem danificados e degradados por condições climáticas e predadores da floresta amazônica. No sistema de plantio, dos 5 ouriços coletados, somente uma amostra proveniente de um ouriço com menos de 5 dias de contato com o solo apresentou contaminação por AFB1, inferior a 0,1 µg/kg de MF. Em armazém ventilado do sistema de plantio, AFB1 foi detectada com teor inferior a 0,1 µg/kg de MF em uma amostra dos 10 ouriços coletados. Todavia no sistema extrativista, os teores de aflatoxinas das castanhas com casca aumentaram e foram superiores ao regulamento europeu (10 µg/kg de MF, UE n°165/2010) ao longo do armazenamento (até 90 dias). A secagem sob ventilação durante o armazenamento não é suficientemente eficaz para atingir rapidamente uma aw inferior a 0,7, evitando o desenvolvimento de fungos aflatoxinogênicos e a produção de aflatoxinas. Resultados sugerem o ouriço como uma barreira de proteção contra estes fungos além de confirmar os estudos anteriores do projeto Safenut que indicam a etapa de secagem sob ventilação e armazenamento das castanhas com casca durante meses no sistema extrativista como etapa crítica na contaminação por aflatoxinas. Portanto, no sistema de plantio, a coleta e o armazenamento após desinfecção com hipoclorito de sódio somente dos ouriços recém caídos das árvores, mesmo por um período de dois meses, permitem evitar a contaminação das castanhas por aflatoxinas

User-definable resource bounds analysis for logic programs

We present a static analysis that infers both upper and lower bounds on the usage that a logic program makes of a set of user-definable resources. The inferred bounds will in general be functions of input data sizes. A resource in our approach is a quite general, user-defined notion which associates a basic cost function with elementary operations. The analysis then derives the related (upper- and lower-bound) resource usage functions for all predicates in the program. We also present an assertion language which is used to define both such resources and resourcerelated properties that the system can then check based on the results of the analysis. We have performed some preliminary experiments with some concrete resources such as execution steps, bytes sent or received by an application, number of files left open, number of accesses to a datábase, number of calis to a procedure, number of asserts/retracts, etc. Applications of our analysis include resource consumption verification and debugging (including for mobile code), resource control in parallel/distributed computing, and resource-oriented specialization

A case of unilateral keloid after bilateral breast reduction

Keloid scar is a manifestation of abnormal wound healing in predisposed individuals. Many treatment modalities have been tried with varying degrees of success. Radiotherapy is one such modality that is widely recognised. We present a case report and literature review based on a patient who developed unilateral keloid scarring following bilateral breast reduction surgery. Some 4 years previously, she had undergone breast conserving surgery followed by adjuvant radiotherapy for breast cancer. After her breast reduction surgery, she developed keloid scarring on the non-irradiated breast only. This case highlights a possible 'preventative' effect of radiotherapy in keloid formation

Parental social contact in the work place and the risk of childhood acute lymphoblastic leukaemia

To study the possible relation between parental social contact through occupation, a marker for a child's risk of infection, and childhood acute lymphoblastic leukaemia (ALL), the parents of 294 children with ALL aged 0–14.9 years and 376 matched controls were interviewed about their jobs after their child's birth up to the age of 3 years. Job titles were assigned to a level of social contact, and an index of occupational social contact months was created using the level and the job duration. Positive interactions between this index and rural residence associated with an increased risk of childhood ALL and common ALL (c-ALL) were observed (interaction P-value=0.02 for both, using tertiles of contact months; interaction P-value=0.05 and 0.02 for ALL and c-ALL, respectively, using continuous contact months); such findings were not observed when job durations were ignored. Our data suggest that duration of parental occupation may be important when examining the association between parental social contact in the workplace and childhood leukaemia

Determinants of Agricultural Pesticide Concentrations in Carpet Dust

Background: Residential proximity to agricultural pesticide applications has been used as a surrogate for exposure in epidemiologic studies, although little is known about the relationship with levels of pesticides in homes