MTBE oxidation byproducts from the treatment of surface waters by ozonation and UV-ozonation.

In recent years, there has been considerable concern over the release of methyl tert-butyl ether (MTBE), a gasoline additive, into the aquifers used as potable water sources. MTBE readily dissolves in water and has entered the environment via gasoline spills and leaking storage tanks. In this paper, we investigate ozonation and UV-ozonation for treatment of MTBE in contaminated drinking water sources. We report the test protocol and results of using solid-phase microextraction (SPME) to determine the level of MTBE and its oxidation byproducts in samples drawn from laboratory-scale ozone and UV-ozone reactors being evaluated at a US EPA research facility. Analysis of a prepared MTBE standard indicated a detection limit on the order of 0.1 microgl(-1) with a repeatability of +/-0.4%. Results show that the overall rate of removal of MTBE via UV-ozonation in a relatively turbid surface water (15 ntu) is twice that of ozonation alone. In addition, GC-MS analysis of decomposition products showed that tert-butyl formate (TBF), methyl acetate, butene, acetone, and acetaldehyde were produced by both processes. TBF and butene reach similar maximum yields from the two processes, but are more efficiently degraded by UV-ozonation treatment. This indicates that these treatment processes also degrade these byproducts. In contrast, the remaining byproducts (methyl acetate, acetone, and acetaldehyde) are formed at similar levels during treatment, but are not degraded once formed. These byproducts may be resistant to hydrogen abstraction by hydroxyl radical.

The public cost of expanding coverage.

The 103d Congress considered several health care reform bills that would encourage voluntary expansions of coverage through insurance market reforms, new tax deductions for premiums, and direct premium subsidies for low-income persons. We found that insurance reforms alone will do little to expand coverage. We also found that most of the proposed tax deductions would go to persons who already have insurance and would have little impact on coverage. Premium subsidies for low-income persons would greatly increase coverage. However, coverage would change little for those who would have to pay all or part of the premium.

Potential public expenditures under managed competition.

This DataWatch estimates the public cost of providing universal coverage under a managed competition model. First, a uniform benefit package is specified; next, the lowest-cost premium for this coverage is estimated, based on average costs in a well-managed health maintenance organization (HMO). Based on these estimates, the cost of premium subsidies and tax revenue effects are determined. It is estimated that if coverage is extended to currently uninsured persons using these estimates and assumptions, spending for these persons will increase 73.9 percent over current levels. The authors estimate a net increase of $47.9 billion in 1993 health spending under a managed competition program with low patient cost sharing. This includes savings of $4.5 billion from wider use of managed care and $11.2 billion in administrative cost savings.

Managing appendicitis in the elderly patient.

The incidence of acute appendicitis in the elderly will continue to increase as the elderly population enlarges. Because appendicitis is much more serious in elderly patients compared to younger patients, the care we render to elderly individuals must be optimal, and recent improvements in care have dropped mortality rates significantly.