H David Stewart

Bioconcentration data for chlorinated organic compounds is analyzed in a response surface technique using molecular connectivity indices to represent the molecular structure of the compounds. The response surface method is described and applied to this data set. The model uses the zero order chi indices, 0 chi and 0 chi v, as the variables in a general two-dimensional parabolic equation. The statistical results suggest a good model for estimation of BCF values: [Formula: see text] The data set is analyzed further in terms of the sigma and delta chi zero indices: sigma x 0 = 0 chi + 0 chi v and delta x 0 = 0 chi - 0 chi v. These transformed chi indices are orthogonal and represent structure information in a useful manner. The sigma x 0 index encodes molecular size and the delta x 0 index encodes electronic features related to pi and lone pair electrons. The structure information in the data set is analyzed in terms of these significant structure features. The data are presented in the form of a contour plot which facilitates analysis and indicates the maximum BCF for this data set.

A compilation of reports of biological effects and related ultrasound exposure levels can be useful in the identification of trends in effects data that may be developing in the literature. The exposures in the experiments reviewed were at frequencies used in medicine. For short (10 minutes or less) continuous wave exposure, with the exception of behavioral effects where variable results have been observed, this tabulation did not identify any in vivo or in vitro effects at spatial peak, temporal average (SPTA) intensities less than 100 mW/cm2. However, a number of effects using pulsed sources with SPTA intensities under this level have been reported. There are several frequently recurring topics in recent reports which include developmental effects and microstructure changes at the cellular level. In addition to animal investigations, there are some limited human epidemiological studies reporting an association between medical ultrasound exposure in utero and developmental effects. Although sufficient research has not been completed to draw conclusions, the findings deserve further investigation. A systematic pattern of directed research on a large scale is not apparent. The available data consist of many scattered studies conducted by individual investigators and groups throughout the world.