Impacts of metal mining on river systems: a global assessment.

An estimated 23 million people live on floodplains affected by potentially dangerous concentrations of toxic waste derived from past and present metal mining activity. We analyzed the global dimensions of this hazard, particularly in regard to lead, zinc, copper, and arsenic, using a georeferenced global database detailing all known metal mining sites and intact and failed tailings storage facilities. We then used process-based and empirically tested modeling to produce a global assessment of metal mining contamination in river systems and the numbers of human populations and livestock exposed. Worldwide, metal mines affect 479,200 kilometers of river channels and 164,000 square kilometers of floodplains. The number of people exposed to contamination sourced from long-term discharge of mining waste into rivers is almost 50 times greater than the number directly affected by tailings dam failures.

Assessment of an implementation of a narrow band, neonatal otoacoustic emission screening method.

OBJECTIVE: To validate a narrow band method for the detection of transient evoked otoacoustic emissions (TEOAEs) in neonates. DESIGN: A method for the assessment of TEOAEs was implemented. The method was based upon assessing the estimated signal to noise ratio of a narrow band of TEOAEs from 1.6 kHz to 2.8 kHz. This method was tested against a commercially available broad band TEOAE test, the Otodynamics ILO88 in quickscreen mode. Trials were performed on 162 ears from a group of normal neonates aged from 3 to 6 wk. RESULTS: The sensitivity of the method was 100% and its specificity was 92%, against the ILO88 test when looking for the absence of TEOAEs. When the ILO88 test was limited in time so that the number of undetected TEOAEs from both tests were similar, the narrow band test took 40% less time than the ILO88 test. CONCLUSIONS: The narrow band TEOAE detection method, as implemented here, did not miss any neonate ears without TEOAEs. However, the narrow band test did not detect TEOAEs in 8% of the group in which TEOAEs were detected by the ILO88. With a two-stage screening test and a 0.6% incidence of sensorineural hearing loss, it is predicted that 1.9% of neonates with TEOAEs would be misclassified, by the narrow band test. (It is predicted that the ILO88 quickscreen test would misclassify 1.1% under the same conditions.) The test is faster and easier to perform than the broad band ILO88 test.

The objective assessment of transient evoked otoacoustic emissions in neonates.

OBJECTIVE: To develop a simple objective method for assessing the presence or absence of a TEOAE in recordings from neonatal ears. DESIGN: Several simple, objective methods of transient evoked otoacoustic emissions (TEOAE) assessment were tested against a verified subjective assessment method, using 200 neonatal TEOAEs recorded under clinical conditions. RESULTS: Total TEOAE level did not correlate well with the subjective assessment. Total estimated signal to noise ratio correlated better with the subjective assessment. Filtering the response between 1.5 and 2.8 kHz and windowing it between 4 and 10 msec did not degrade the correlation. In a normal population of neonates the filterd, windowed estimated signal to noise ratio method miscategorized only 4.0% of the responses as having no TEOAEs. None of the population without TEOAEs were categorized as having TEOAEs by the objective test. CONCLUSIONS: An objective TEOAE assessment (based on the signal to noise ratio of a time limited midband section of the TEOAE) performed well at detecting the presence or absence of a TEOAE.

Quantitative assessment of methods for the detection of otoacoustic emissions.

OBJECTIVE: To compare the performance of various types of signal detector commonly used to detect otoacoustic emissions (OAEs). METHOD: The signal detectors were tested with signals in various types of noise, including noise with various amplitude distributions. Commonly utilized transient evoked OAE and distortion product OAE detectors were analyzed. RESULTS: In both cases it was found that detector performance increased as the measurement bandwidth was increased. Noises of different amplitude distributions were found to affect the performance of both types of detectors. The effect of different amplitude distributions decreased as the measurement bandwidth was increased. For a given power per spectral line, the transient evoked OAE detector could detect signals 6 dB farther into gaussian noise than the distortion product OAE detector. CONCLUSIONS: An analysis of the results of practical methods of OAE measurement show that distortion product OAEs can be measured with higher power per spectral line than transient evoked OAEs. This means that in adult humans distortion product OAEs can be reliably detected in about 1/14th of the time of transient evoked OAEs. In neonatal humans distortion product OAEs can be reliably detected in about two-thirds of the time of transient evoked OAEs.

Mental health crisis in California.

Over the last 30 years, California dejure (legislated) mental health policy has been based on deinstitutionalization and outpatient care through community mental health systems. But by the end of the 1970s, there was a growing concern over whether deinstitutionalization had successfully occurred, whether community mental health systems had failed and whether mental health systems had ever been adequately funded. In a national study released in 1990, California was named one of four states where mental health delivery has regressed in the past two years. A review of current California mental health policies indicates dejure and defacto policies are not the same. Most mental health dollars are going to state hospitals and community acute inpatient facilities. Budgets for community mental health have been steadily eroded, and the current mental health system is in crisis. Implementation of mental health policy is dependent on intergovernmental financing, and each level of government tries to avoid costs. Definitions of which clients are to be served remain unclear while pressures for more social control mount. Mental health remains segregated from physical health policy-making and continues to operate at a political disadvantage in general fund budget battles.