Mutagens in contaminated soil: a review

The intentional and accidental discharges of toxic pollutants into the lithosphere results in soil contamination. In some cases (e.g., wood preserving wastes, coal-tar, airborne combustion by-products), the contaminated soil constitutes a genotoxic hazard. This work is a comprehensive review of published information on soil mutagenicity. In total, 1312 assessments of genotoxic activity from 118 works were examined. The majority of the assessments (37.6%) employed the Salmonella mutagenicity test with strains TA98 and/or TA100. An additional 37.6% of the assessments employed a variety of plant species (e.g., Tradescantia clone 4430, Vicia faba, Zea mays, Allium cepa) to assess mutagenic activity. The compiled data on Salmonella mutagenicity indicates significant differences (p \u3c 0.0001) in mean potency (revertents per gram dry weight) between industrial, urban, and rural/agricultural sites. Additional analyses showed significant empirical relationships between S9-activated TA98 mutagenicity and soil polycyclic aromatic hydrocarbon (PAH) concentration (r2 = 0.19 to 0.25, p \u3c 0.0001), and between direct-acting TA98 mutagenicity and soil dinitropyrene (DNP) concentration (r2 = 0.87, p \u3c 0.0001). The plant assay data revealed excellent response ranges and significant differences between heavily contaminated, industrial, rural/agricultural, and reference sites, for the anaphase aberration in Allium cepa (direct soil contact) and the waxy locus mutation assay in Zea mays (direct soil contact). The Tradescantia assays appeared to be less responsive, particularly for exposures to aqueous soil leachates. Additional data analyses showed empirical relationships between anaphase aberrations in Allium, or mutations in Arabidopsis, and the 137Cs contamination of soils. Induction of micronuclei in Tradescantia is significantly related to the soil concentration of several metals (e.g., Sb, Cu, Cr, As, Pb, Cd, Ni, Zn). Review of published remediation exercises showed effective removal of genotoxic petrochemical wastes within one year. Remediation of more refractory genotoxic material (e.g., explosives, creosote) frequently showed increases in mutagenic hazard that remained for extended periods. Despite substantial contamination and mutagenic hazards, the risk of adverse effect (e.g., mutation, cancer) in humans or terrestrial biota is difficult to quantify

Do You Have Enough Forage?

4 pp., 2 tables, 2 figuresTo limit the impact of a forage crisis, a rancher must be able to recognize forage shortfalls and make timely decisions for the good of the livestock and the enterprise. This publication discusses strategies that help ranchers determine exactly how much forage they need, how much is available, and how to manage the herd and the forage resources to ensure financial survival

The Devil's in the Tail: Residential Mortgage Finance and the U.S. Treasury

This paper seeks to contribute to the U.S. housing finance reform conversation by providing a critical assessment of the various types of policy proposals that have been offered. There appears to be a broad consensus to maintain explicit government guarantees for certain narrowly defined borrower populations, such as FHA insurance guarantees for low- and moderate-income and first-time homebuyers. However, the expected role of the federal government in the broader housing finance system is in dispute: ranging from no role; to insuring against only extreme or tail events; to insuring against all losses. However, most proposals agree that any public insurance be priced and available only for loans meeting pre-specified criteria in an effort to limit taxpayer exposure

A longitudinal study of self-assessment accuracy

Although studies have examined medical students' ability to self-assess their performance, there are few longitudinal studies that document the stability of self-assessment accuracy over time. This study compares actual and estimated examination performance for three classes during their first 3 years of medical school. Methods  Students assessed their performance on classroom examinations and objective structured clinical examination (OSCE) stations. Each self-assessment was then contrasted with their actual performance using idiographic (within-subject) methods to define three measures of self-assessment accuracy: bias (arithmetic differences of actual and estimated scores), deviation (absolute differences of actual and estimated scores), and covariation (correlation of actual and estimated scores). These measures were computed for four intervals over the course of 3 years. Multivariate analyses of variance and correlational analyses were used to evaluate the stability of these measures. Results  Self-assessment accuracy measures were relatively stable over the first 2 years of medical school with a decease occurring in the third year. However, the correlational analyses indicated that the stability of self-assessment accuracy was comparable to the stability of actual performance over this same period. Conclusion  The apparent decline in accuracy in the third year may reflect the transition from familiar classroom-based examinations to the substantially different clinical examination tasks of the third year OSCE. However, the stability of self-assessment accuracy compares favorably with the stability of actual performance over this period. These results suggest that self-assessment accuracy is a relatively stable individual characteristic that may be influenced by task familiarity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75505/1/j.1365-2923.2003.01567.x.pd

Stocking Rate Decisions: Key to Successful Ranch Management.

12 p

Range Monitoring with Photo-points

6 pp., 2 photosPhoto-points provide a way for owners/managers to monitor rangeland health with a minimum of time and expense. This publication explains when, where and how often to photograph rangeland points, how to set up a photo point, and how to interpret the photographs