Integration of aquatic fate and ecological responses to linear alkyl benzene sulfonate (LAS) in model stream ecosystems.

An integrated model stream ecosystem fate and effect study of dodecyl linear alkylbenzene sulfonate (C(12)LAS) was performed in the summer and fall of 1996. The study addressed responses of periphytic microbes, immature benthic fauna including abundance, drift, and emergence of adult insects in a 56-day exposure. Exposures ranged from 126 to 2978 microg/L and were continuously presented in a single-pass, flow-through test system. Microbial heterotrophs acclimated to C(12)LAS exposure quickly (14 days) and biodegraded C(12)LAS at all concentrations. Blue-green algae responded by increasing in abundance with increasing C(12)LAS concentration. Invertebrates responded by increased drift and reduced benthic abundances at concentrations exceeding 293 microg/L. Emergence at 927 microg/L also declined relative to the control. Adverse responses for mayflies and chironomids were indicated using univariate statistical techniques. Multivariate techniques indicated these taxa plus mollusks, aquatic worms, caddisflies, and stoneflies were impaired at some concentrations. Bioavailability of C(12)LAS was investigated in streams as a function of the total suspended solid load in the water column driven by local weather and watershed patterns. A continuous bioavailability model indicated exposure was reduced by an average of 8.5+/-8.9%. A model ecosystem no-observed-effect concentration (NOEC) was concluded to be 293 microg/L based on measured water column exposure and adjusted to 268 microg/L by the bioavailability model. A literature review of 13 available model ecosystem studies was conducted and NOEC conclusions were adjusted by a structure-activity relationship to a dodecyl chain length (sulfophenyl position and distribution being ignored due to lack of information in the reviewed studies). Lentic studies (n=7) were found to have higher NOECs than lotic studies (n=6) and were more variable. Mean NOECs+/-SD for all studies, lentic studies only, and lotic studies only were 3320+/-6040, 5720+/-7640, and 530+/-430 microg/L, respectively. Interpretation of results for anomalies from specific studies suggests the importance of experimental design, use of laboratory versus natural surface water, biological complexity of the test system, and physical test system design as relevant factors for consideration. The specific results of the new model ecosystem study presented in this article can be well defended on the basis of a robust experimental and physical design and because the system contained a diverse and sensitive aquatic community. A low or no uncertainty factor could be applied to the result.

Hearing loss and otitis media in velo-cardio-facial syndrome.

There is an increased prevalence of otitis media and associated hearing loss in patients with isolated cleft or submucous cleft palates, palatal abnormalities which are well known components of velo-cardio-facial syndrome (VCFS). The records of 166 VCFS patients were reviewed for the purpose of documenting the prevalence of middle ear disease and associated conductive hearing loss in patients with VCFS. Patients were divided according to age, type of palatal abnormality and presence or absence of chromosomal deletion using fluorescence hybridization test. Results indicated that the prevalence of middle ear disease in patients with VCFS was 47% and the prevalence of hearing loss was 44%, the majority of which was conductive and due to middle ear disease (74%) and 11% of which was sensorineural. There was no statistical difference between groups using the chi2-test with regard to age, type of palatal abnormality and presence of chromosomal deletion. The prevalence of conductive hearing loss secondary to middle ear disease in VCFS is comparable to the prevalence found in isolated cases of cleft palate.

The effect of exercise on depressive symptoms in the moderately depressed elderly.

Thirty community-dwelling, moderately depressed elderly were randomly assigned to 1 of 3 interventions: experimenter-accompanied exercise in the form of walking, a social contact control condition, and a wait-list control. Exercise and social contact both resulted in significant reductions in both the total and the psychological subscale of the Beck Depression Inventory (BDI). The exercise condition, however, unlike the control conditions, resulted in decreased somatic symptoms of the BDI. These results indicate that, at least in the short term, exercise has a broader effect compared with control conditions in reducing depressive symptoms in the moderately depressed elderly.