Maternal and Paternal Household Pesticide Exposure During Pregnancy and Risk of Childhood Acute Lymphoblastic Leukemia.

OBJECTIVE: The aim of this study was to investigate whether risk estimates for childhood acute lymphoblastic leukemia change when restricting model comparison groups to "nonpesticide exposure" (NPE10) households. METHODS: Cases ( n = 1810) 15 years or younger were identified through Children's Cancer Group institutions between 1989 and 1993 and age-/sex-matched to controls ( n = 1951). Household pesticide use during pregnancy/month prior was collected via telephone. NPE10 comparison group reporting no parental exposure to 10 pesticide classes was identified. RESULTS: Adjusted odds ratios increased from 15% to 49% when limiting the comparison to NPE10. Maternal termite insecticide exposure was associated with greatest risk (adjusted odds ratio, 4.21; 95% confidence interval, 2.00-8.88). There was minimal evidence of interaction by child sex or occupational pesticide exposure, and no monotonic dose-response pattern with frequency of use (times per year). CONCLUSIONS: Elevated risks are consistent with published pooled-/meta-analyses and DNA damage. The consistency and magnitude of these associations warrant product labeling, exposure reduction interventions, or both.

Theory of coupled resistive drift and resistive drift ballooning instabilities in fusion plasma.

Drift wave instabilities (DWI) associated with the two-fluid dynamics seems to be responsible for anomalous transport in modern day tokamaks. Ballooning instabilities tend to exchange flux tubes of different pressure, resulting in convective transport. The micro-level turbulence (drift wave) is coupled with the macro-level (ballooning mode) dynamics in fusion experiments. The co-existence of DWI and drift ballooning instabilities (DBI) is discussed in this work using a four-field plasma model. The formulation preserves both the microscopic and macroscopic dynamics of plasma. To demonstrate the coupling, a new dispersion relation is derived to analyze stability of the coupled modes in a non-uniform magnetized plasma. Linear stability of coupled drift-ballooning and drift-acoustic modes have been explored. The two-fluid effect (micro-level influence) through diamagnetic drift frequency for electrons and curvature drift frequency on unstable modes are demonstrated.

Resistive drift instabilities for thermal and non-thermal electron distributions in electron-ion plasma.

Local dispersion relations for resistive drift mode in a nonuniform magnetize plasma are derived for thermal and non-thermal distribution of electrons. The coupled mode equations are obtained by using Braginskii's transport equations for ions and electrons with thermal as well as non-thermal (Cairns and kappa) distribution for electrons. The dispersion relations are then analyzed both analytically as well as numerically for all distributions. It is found that growth rate is highest for Maxwellian, Intermediate for kappa and lowest for Cairns distribution. It has been found that increasing values of Γ (which estimate population of non-thermal electrons) for Cairn distributed electrons are able to stabilize the mode. Furthermore, increasing the values of κ (which is spectral index) for the kappa distributed electrons have destabilizing effects on the mode. The result might be useful in the interpretation of electromagnetic fluctuations in nonuniform magneto-plasma in which resistivity is a key element in calculation of drift instabilities in the presence of thermal or nonthermal electron distributions, such systems are extensively observed in laboratory as well as space plasma.