Population amalgamation and genetic variation: observations on artificially agglomerated tribal populations of Central and South America.

The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations of Central and South America, analyzing the pooled sample as though it were a single population. Several striking findings emerge. (1) Mean heterozygosity is not sensitive to agglomeration, but the number of different alleles (allele count) is inflated, relative to neutral mutation/drift/equilibrium expectation. (2) The inflation is most serious for rare alleles, especially those which originally occurred as tribally restricted "private" polymorphisms. (3) The degree of inflation is an increasing function of both the number of populations encompassed by the sample and of the genetic divergence among them. (4) Treating an agglomerated population as though it were a panmictic unit of long standing can lead to serious biases in estimates of mutation rates, selection pressures, and effective population sizes. Current DNA studies indicate the presence of numerous genetic variants in human populations. The findings and conclusions of this paper are all fully applicable to the study of genetic variation at the DNA level as well.

Establishing occupational and environmental health design requirements for Lunar and Mars settlements

In a study of Lunar and Mars settlement concepts, an analysis was made of fundamental design assumptions in five technical areas against a model list of occupational and environmental health concerns. The technical areas included the proposed science projects to be supported, habitat and construction issues, closed ecosystem issues, the "MMM" issues--mining, material-processing, and manufacturing, and the human elements of physiology, behavior and mission approach. Four major lessons were learned. First it is possible to relate public health concerns to complex technological development in a proactive design mode, which has the potential for long-term cost savings. Second, it became very apparent that prior to committing any nation or international group to spending the billions to start and complete a lunar settlement, over the next century, that a significantly different approach must be taken from those previously proposed, to solve the closed ecosystem and "MMM" problems. Third, it also appears that the health concerns and technology issues to be addressed for human exploration into space are fundamentally those to be solved for human habitation of the earth (as a closed ecosystem) in the 21st century. Finally, it is proposed that ecosystem design modeling must develop new tools, based on probabilistic models as a step up from closed circuit models. ^

Negotiated settlements: The utilities, multiple regulators and clean air

Utilities have made strides in reducing air pollutant levels, but the proposed 1990 Clean Air Act Amendments call for even greater reductions and more stringent enforcement. Federal and state air enforcement agencies now encourage the use of negotiated settlements as a way to bring about compliance. This research examines the operation of such procedures in 19 case studies and a formal survey with the negotiators to account for the differences in the nature of the settlements and to identify the factors contributing to their perceived success. ^

Chronic volatile substance abuse among the adult Kickapoo traditional tribe of Texas: Disease and disability profiles, neuropsychosocial consequences, and social implications for treatment

The purpose of this study, based on secondary data from attendees at a substance abuse clinic for the Kickapoo Healing Grounds in Eagle Pass, Texas, is two fold: (1) to elucidate neuro-behavioral performance of volatile substance abusers in the Kickapoo tribe and (2) to determine factors associated with their treatment completion and rehabilitation as measured by their employment at follow-up. Volatile substance abuse (VSA) is associated with a host of neurological manifestations, and secondary prevention or clinical treatment and rehabilitation remains the mainstay of control efforts. Very little is known about VSA in general, and especially among Native American populations. It is anticipated that the results will help determine and assist other tribes and non-tribal substance abuse centers with treatment planning for volatile substance abusers among Native American populations. ^

Findings of the University of Texas Health Science Center at San Antonio's Dental School pilot mobile van program in Laredo, Texas

Lack of access to oral health care frequently affects those of lower socio-economic level; individuals in this group experience more dental decay, and the caries experience is more likely to be untreated. Inadequate dental care access may be attributed to exclusion that is due to income, geography, age, race or ethnicity. Objective: The present study aims were to: (1) determine how oral disease prevalence and access to dental services in four US-Mexico Border unincorporated low socioeconomic settlements identified as colonias compare to each other and Laredo, Texas, and (2) determine if insurance status affects dental care access and/or disease prevalence. Methods: A secondary analysis of data from a retrospective chart review of 672 patients attending a Mobile Dental Van Program in the Webb County colonias. Demographic information, (ethnicity, age, gender, insurance coverage and colonia site), dental visits within past year, insurance status, presence of dental sealants, prevalence of untreated dental decay (caries), and presence of gum disease (gingivitis and periodontitis) were extracted. Pearson's chi-square tests (χ2) were computed to compare the prevalence of these outcomes between colonias and Laredo and their potential association with insurance status. Results: For 6 - 11 year olds, dental visits in the past year were lower for colonias (39%), than Laredo (58.5%) (p<0.002). Caries prevalence was higher for colonias (56.6%), than Laredo (37.1%) (p<0.001). Gum disease prevalence was higher in colonias (73%), than in Laredo (21.4%) (p<0.001). No significant differences were noted for caries (χ2=1.73; p<0.188) and gum disease (χ2=0.0098; p<0.921) by patient's insurance status. For adults 36 - 64 years of age, dental visits in the past year were lower in colonias (22.4%), than Laredo (36.3%) (p<0.001). Caries prevalence was higher for colonias (78.3%), than Laredo (54.0%) (p<0.001). Gum disease prevalence was also higher among colonias (91.3%) than Laredo (61.3%) (p<0.001). No significant differences were noted for caries (χ2=0.0010; p<0.975) and gum disease (χ2=0.0607; p<0.805) by patient's insurance status. Conclusion: Colonia residents seeking dental care at a Mobile Dental Van Program in Webb County have significantly higher prevalence of oral disease regardless of insurance status.^