Polycyclic aromatic hydrocarbons in residential dust and risk of childhood acute lymphoblastic leukemia.

Several polycyclic aromatic hydrocarbons (PAHs) are known or probable human carcinogens. We evaluated the relationship between PAH exposure and risk of childhood acute lymphoblastic leukemia (ALL) using concentrations in residential dust as an exposure indicator. We conducted a population-based case-control study (251 ALL cases, 306 birth-certificate controls) in Northern and Central California from 2001 to 2007. We collected residential dust using a high volume small surface sampler (HVS3) (n=185 cases, 212 controls) or by sampling from participants' household vacuum cleaners (n=66 cases, 94 controls). We evaluated log-transformed concentrations of 9 individual PAHs, the summed PAHs, and the summed PAHs weighted by their carcinogenic potency (the toxic equivalence). We calculated odds ratios (ORs) and 95% confidence intervals (CI) using logistic regression adjusting for demographic characteristics and duration between diagnosis/reference date and dust collection. Among participants with HVS3 dust, risk of ALL was not associated with increasing concentration of any PAHs based on OR perln(ng/g). Among participants with vacuum dust, we observed positive associations between ALL risk and increasing concentrations of benzo[a]pyrene (OR perln[ng/g]=1.42, 95% CI=0.95, 2.12), dibenzo[a,h]anthracene (OR=1.98, 95% CI=1.11, 3.55), benzo[k]fluoranthene (OR=1.71, 95% CI=0.91, 3.22), indeno[1,2,3-cd]pyrene (OR=1.81, 95% CI=1.04, 3.16), and the toxic equivalence (OR=2.35, 95% CI=1.18, 4.69). The increased ALL risk among participants with vacuum dust suggests that PAH exposure may increase the risk of childhood ALL; however, reasons for the different results based on HVS3 dust samples deserve further study.

Determinants of organophosphorus pesticide urinary metabolite levels in pregnant women from the CHAMACOS cohort.

Organophosphosphorus pesticides (OPs) are widely used as insecticides in agriculture. Human exposure to OPs has been linked to adverse effects including poorer child neurodevelopment, reduced birth weight, altered serum hormone levels, and reduced semen quality. We measured six OP dialkyl phosphate (DAP) metabolites [three dimethyl alkylphosphates (DMs) and three diethyl alkylphosphates (DEs)] in urine samples collected two times during pregnancy (~13 and ~26 weeks gestation) from 594 women participating in the CHAMACOS birth cohort study and resided in an agricultural community in the United States (U.S.) between 1999 and 2000. Previous studies have shown these women have higher OP exposures compared with the general U.S. population. We examined bivariate associations between prenatal DAP metabolite levels and exposure determinants such as age, season, years living in the US, housing characteristics, fruit and vegetable consumption, occupation and residential proximity to agricultural fields. Final multivariable models indicated that season of urine collection was significantly associated (p < 0.01) with specific gravity-adjusted DM, DE and total DAP metabolites; samples collected in fall and winter had higher concentrations than those collected in spring-summer. Specific gravity-adjusted levels of DM and total DAP metabolites were significantly higher in women who had resided in the U.S. for 5 years or less (p < 0.05). Levels of DM metabolites also increased with daily fruit and vegetable servings (p < 0.01), and levels of DE metabolites were higher in residences with poorer housekeeping quality (p < 0.01) and in mothers that worked in agriculture (p < 0.05). These findings suggest that there are multiple determinants of OP exposure in pregnant women.

Agricultural pesticide use in California: pesticide prioritization, use densities, and population distributions for a childhood cancer study.

Several studies have suggested an association between childhood cancer and pesticide exposure. California leads the nation in agricultural pesticide use. A mandatory reporting system for all agricultural pesticide use in the state provides information on the active ingredient, amount used, and location. We calculated pesticide use density to quantify agricultural pesticide use in California block groups for a childhood cancer study. Pesticides with similar toxicologic properties (probable carcinogens, possible carcinogens, genotoxic compounds, and developmental or reproductive toxicants) were grouped together for this analysis. To prioritize pesticides, we weighted pesticide use by the carcinogenic and exposure potential of each compound. The top-ranking individual pesticides were propargite, methyl bromide, and trifluralin. We used a geographic information system to calculate pesticide use density in pounds per square mile of total land area for all United States census-block groups in the state. Most block groups (77%) averaged less than 1 pound per square mile of use for 1991-1994 for pesticides classified as probable human carcinogens. However, at the high end of use density (> 90th percentile), there were 493 block groups with more than 569 pounds per square mile. Approximately 170,000 children under 15 years of age were living in these block groups in 1990. The distribution of agricultural pesticide use and number of potentially exposed children suggests that pesticide use density would be of value for a study of childhood cancer.

Determinants of manganese levels in house dust samples from the CHAMACOS cohort.

INTRODUCTION: Manganese (Mn) is an essential nutrient, but at high exposure levels Mn is a neurotoxicant. The fungicides maneb and mancozeb are approximately 21% Mn by weight and more than 150,000 kg are applied each year to crops in the Salinas Valley, California. It is not clear, however, whether agricultural use of these fungicides increases Mn levels in homes. MATERIALS AND METHODS: We collected house dust samples from 378 residences enrolled in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study with a second sample collected approximately nine months later from 90 of the residences. House dust samples were analyzed for Mn using inductively coupled plasma optical emission spectroscopy. Information from interviews, home inspections, and pesticide use reports was used to identify potential predictors of Mn dust concentrations and loadings. RESULTS: Mn was detectable in all dust samples. The median Mn concentration was 171 µg/g and median Mn loading was 1,910 µg/m(2) at first visit. In multivariable models, Mn dust concentrations and loadings increased with the number of farmworkers in the home and the amount of agricultural Mn fungicides applied within three kilometers of the residence during the month prior to dust sample collection. Dust concentrations of Mn and other metals (lead, cadmium and chromium) were higher in residences located in the southern Salinas Valley compared those located in other areas of the Salinas Valley. Dust loadings of Mn and other metals were also higher in residences located on Antioch Loam soil than other soil types, and in homes with poor or average housekeeping practices. CONCLUSIONS: Agricultural use of Mn containing fungicides was associated with Mn dust concentrations and loadings in nearby residences and farmworker homes. Housekeeping practices and soil type at residence were also important factors related to dust metal concentrations and loadings.