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Fixed-ratio ray designs have been used for detecting and characterizing interactions of large numbers of chemicals in combination. Single-chemical dose-response data are used to predict an “additivity curve” along an environmentally relevant ray. A “mixture curve” is estimated from the mixture dose-response data along the ray. A test of additivity is equivalent to a test of coincidence of these two curves, which is based on the traditional hypothesis testing framework that assumes additivity in the null hypothesis and rejects with evidence of interaction. However, failure to reject may be due to lack of statistical power, making the claim of additivity problematic. As a solution we have developed rigorous methodology to test for additivity using statistical equivalence testing logic in which additivity is claimed based on pre-specified biologically important additivity margins, if the data support such a claim. Using the principle of confidence interval inclusion, a confidence region about the difference of meaningful functions of model parameters from the mixture model and that predicted under additivity is computed. When the confidence region is completely contained within the additivity margins then additivity is claimed with a Type I error rate chosen a priori to be some acceptably small value. The method is illustrated using an environmentally relevant fixed-ratio mixture of nine haloacetic acids where cytotoxic response is measured.

The identification of soybean rust, caused by Phakopsora pachyrhizi H. Sydow & Sydow, in the southern United States in November 2004 (Schneider et al. 2005), in the Midwest in 2006 (Hartman et al. 2007), and elsewhere has increased the concerns of the impact of the pathogen on US soybean production (Miles et al. 2007). The rapid spread of P. pachyrhizi and its potential to cause severe yield losses makes this among the most destructive foliar diseases of soybean. Yield losses of 20%–60% were reported in Asia, with losses of 80% reported from experimental plots in Taiwan (Hartman et al. 1991). Soybean rust could have a major impact on both total soybean production and production costs in the US. The primary control of soybean rust has been with fungicides (Miles et al. 2003). There are four fungicides commercially available in the US that are registered for use on soybean and labeled for soybean rust. These fungicides are Bravo , Echo , Headline , and Quadris . Headline and Quadris are strobilurin products; Bravo and Echo are chlorothalonil products. In addition, there have recently been Section 18 Emergency Exemption requests for additional fungicidal compounds (myclobutanil, tebuconazole, propiconazole, tetraconazole, and trifloxystrobin) and mixtures of compounds (trifloxystrobin and propiconazole; propiconazole and azoxystrobin; and pyraclostrobin and tebuconazole) submitted to the EPA by the Departments of Agriculture from many states (U.S. EPA 2006a). A number of commercial products (e.g., Bumper , UpperCut , Quilt , Laredo , and Stratego ) containing these requested fungicidal compounds have been approved and may now be registered (Section 3 registration status) for management of soybean rust on soybean (U.S. EPA 2006a). While these fungicides have been used on crops (e.g., fruits, vegetables, and cereals), many questions remain regarding the large-scale application of these compounds to soybeans (~74 million acres in the US) in the prevention and treatment of soybean rust. Indeed, there is growing concern about the use of these fungicides since little is known about the toxicity of many of these compounds and their impact on human health. Therefore, the goals of this project were to assess the toxicity of soybean rust fungicides (Table 1) using a mammalian cell cytotoxicity assay and to compare the cytotoxicity (%C1/2) of these fungicides to the published toxicity values of other agrichemicals (insecticides and herbicides).

A new and general approach is proposed to analyze the dynamics of a colloidal particle interacting with a nearby wall. This analysis can be used to determine the acting forces even when the system is non-stationary. As an illustration, we use total internal reflection microscopy to investigate the forces acting on a polystyrene sulfate latex particle as it is receding from a charged glass surface.

Municipal solid waste incineration (MSWI) significantly reduces volume and mass by as much as 80%, prolonging the life span of landfills. The concentration of heavy metals in the ash and their ability to leach into ground water is a serious concern when siting and designing MSWI ash landfills. Improved technology captures most heavy metals in the ash. The distribution of elements among the different ash particle sizes was determined by NAA. The bottom ash residue was separated into fractions ranging from ≥9.5 mm to ≤0.3 mm. The fly ash was separated into fractions from ≥250 μm to ≤20 μm. Landfills usually bury a mixture of both. The combined ash was separated into fractions over the entire range from >9.5 mm to

Am Beispiel der osmotischen Diurese sollten die Beziehungen zwischen Weite der Harnkanalchen und Starke der Harnausscheidung geklart werden. Zu diesem Zwecke wurde bei drei Gruppen von weisen Mausen eine osmotische Diurese durch intravenose Injektion von 0,2 cm3 50%iger Saccharose-, 0,4 cm3 25% iger Mannit- und 0,4 cm3 einer 10%igen Na2SO4-Losung erzeugt und die Versuchstiere in verschiedenen Zeitabstanden getotet. Durch Planimetrie wurde die Weite der Harnkanalchenlichtungen aller Segmente des Nephrons im Verlauf der osmotischen Diurese ermittelt und auserdem fur die TcI und TcII die primaren SR und DB die Epithel- und Gesamtflache bestimmt.

The genotoxicity of extracts of anaerobically digested sewage sludge to human cells was assessed by measuring the induction of sister chromatid exchanges in human peripheral lymphocytes with and without mammalian hepatic microsomal activation. A 2 hr exposure time with a total culture time of 76 hr was necessary to circumvent problems with cell cycle delays induced by the agents present in the extracts. With this modified procedure, the three extracts tested demonstrated a statistically significant increase in the number of sister chromatid exchanges/chromosome observed suggesting the presence of a genotoxic component in the sewage sludge.