Pickering emulsion-enhanced Vibrio fischeri assay for ecotoxicity assessment of highly hydrophobic polycyclic aromatic hydrocarbons.

Accurate ecotoxicity assessment of contaminated soil is critical to public health, and the luminescent bacteria (Vibrio fischeri) method is the most commonly used. Hydrophobic compounds such as polycyclic aromatic hydrocarbons (PAHs) in soil cannot be in contact with luminescent bacteria due to their low water solubility so that the luminescence inhibitory effect cannot be observed. The underestimated biological toxicity makes the test unreliable and en-dangers public health and safety. The commonly adopted improved method of adding cosolvents has limited effect, it was only effective for low-hydrophobicity chemicals and could not be used for ecotoxicity evaluation of high-hydrophobicity chemicals. Therefore, we constructed Pickering emulsions using luminescent bacteria modified with n-dodecanol in which PAHs were dissolved in the oil phase, n-tetradecane. Then the luminescent bacteria could tightly adhere to the oil-water interface and contact PAHs. As a result, their bioluminescence was suppressed to varying degrees depending on the chemical species and concentrations. With no solubility limitation, highly hydrophobic PAHs could even completely inhibit bacterial bioluminescence, hence the toxicity information was accurately displayed and the median effect concentration (EC50) values could be calculated. This Pickering emulsion-based method was successfully applied for the accurate ecotoxicity evaluation of highly hydrophobic PAHs and soil samples contaminated with them, which all previous methods could not achieve. This method overcomes the problem of ecotoxicity evaluation of hydrophobic compounds, and has great potential for practical application, whether it is pure chemicals or various real samples from the ecological environment.

Within-state geographic patterns of health insurance coverage and health risk factors in the United States.

BACKGROUND: A number of health risk factors have been associated with the incidence and mortality of common diseases. Although knowing risk factor patterns at a small-area level would be useful for ecologic analyses and prevention program planning, risk factor data are generally published only at the state or regional level in the United States. This study presents maps of within-state patterns of several such factors. METHODS: Responses to Behavioral Risk Factor Surveillance System (BRFSS) questions about smoking, obesity, health insurance, and mammography use were aggregated for 1992-1998 by county. These data were then geographically smoothed by adjusting each county's proportional response based on the responses of its neighboring counties. RESULTS: The maps show risk factor patterns consistent with published state-level maps, but also identify within-state variations masked by aggregation to the larger geographic units. CONCLUSIONS: The risk factor maps presented should permit a better understanding of localized patterns of health risk behaviors and access to health care as well as help to target intervention activities in the U.S. areas that most need them.