Exposure Reconstruction for the TCDD-Exposed NIOSH Cohort Using a Concentration- and Age-Dependent Model of Elimination

Recent studies demonstrating a concentration dependence of elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suggest that previous estimates of exposure for occupationally exposed cohorts may have underestimated actual exposure, resulting in a potential overestimate of the carcinogenic potency of TCDD in humans based on the mortality data for these cohorts. Using a database on U.S. chemical manufacturing workers potentially exposed to TCDD compiled by the National Institute for Occupational Safety and Health (NIOSH), we evaluated the impact of using a concentration- and age-dependent elimination model (CADM) (Aylward et al., 2005) on estimates of serum lipid area under the curve (AUC) for the NIOSH cohort. These data were used previously by Steenland et al. (2001) in combination with a first-order elimination model with an 8.7-year half-life to estimate cumulative serum lipid concentration (equivalent to AUC) for these workers for use in cancer dose-response assessment. Serum lipid TCDD measurements taken in 1988 for a subset of the cohort were combined with the NIOSH job exposure matrix and work histories to estimate dose rates per unit of exposure score. We evaluated the effect of choices in regression model (regression on untransformed vs. ln-transformed data and inclusion of a nonzero regression intercept) as well as the impact of choices of elimination models and parameters on estimated AUCs for the cohort. Central estimates for dose rate parameters derived from the serum-sampled subcohort were applied with the elimination models to time-specific exposure scores for the entire cohort to generate AUC estimates for all cohort members. Use of the CADM resulted in improved model fits to the serum sampling data compared to the first-order models. Dose rates varied by a factor of 50 among different combinations of elimination model, parameter sets, and regression models. Use of a CADM results in increases of up to five-fold in AUC estimates for the more highly exposed members of the cohort compared to estimates obtained using the first-order model with 8.7-year half-life. This degree of variation in the AUC estimates for this cohort would affect substantially the cancer potency estimates derived from the mortality data from this cohort. Such variability and uncertainty in the reconstructed serum lipid AUC estimates for this cohort, depending on elimination model, parameter set, and regression model, have not been described previously and are critical components in evaluating the dose-response data from the occupationally exposed populations.     

Beheimatungsprozesse begleiten — ein Werkstattbericht

Supporting processes of belonging in supervision and coachingThe contemporary employee has to cope with frequent changes. Not only does he lose his familiar environment, he also has to find ways to familiarize himself with new places and to develop a fresh sense of belonging. This process can be understood and facilitated by interpreting the German concept of “Heimat“ as something we have to create ourselves. First experiences demonstrate the usefulness of this approach in coaching processes.     

Expected sample moments of concomitants of selected order statistics

In this paper, the task of determining expected values of sample moments, where the sample members have been selected based on noisy information, is considered. This task is a recurring problem in the theory of evolution strategies. Exact expressions for expected values of sums of products of concomitants of selected order statistics are derived. Then, using Edgeworth and Cornish-Fisher approximations, explicit results that depend on coefficients that can be determined numerically are obtained. While the results are exact only for normal populations, it is shown experimentally that including skewness and kurtosis in the calculations can yield greatly improved results for other distributions.     

The U.S. legalization program: a preliminary final report

The Immigration Reform and Control Act (IRCA) of 1986 made 4 types of aliens eligible to receive legalization benefits: 1) those who resided "continuously" in the US since January 1, 1982; 2) those who had worked in the US perishable-crop agriculture for 90 "man-days" in specified time periods (Special Agricultural Workers [SAWS]); 3) those who were in the US since before January 1, 1972; and 4) those classified as Cuban/Haitian entrants and who had been in the US since January 1, 1982. Estimates of the number of aliens eligible for legalization, not including SAWS, ranges from 1.834 million to 2.56 million. Estimates of undercounts of undocumented aliens are 10% for those who entered before 1975 and 37.5% for those who arrived after 1975. Other refinements in the estimates of undocumented aliens include adjustments for 1) ethnic group and location, 2) the growth of the undocumented population between the census date and the legalization eligibility date under IRCA, and 3) emigration and deportation rates. Out of the 1,581,800 applicants entered into the Immigration and Naturalization Service (INS) computers (from a total of 2.15 million applicants) as of May 20, 1988, 73.7% were Mexican nationals. Only 5 other countries contributed more than 1%: El Salvador (6.5%), Haiti (2.3%), Guatemala (2.2%), the Philippines (1%), and Colombia (1%). The Mexican percentage was unexpectedly high, perhaps because the legalization had been much more successful in the Southwest than anywhere else in the country. Reasons that Mexicans have a higher legalization participation rate than other nationalities include 1) the distant eligibility date; 2) ethnic differences among non-Mexican nationalities; 3) particularly in the northeast, fears of exposing one's illegal status to INS; 4) the difficulty of information reaching ethnic communities, 5) the reluctance of those already undergoing the naturalization process to risk the legalization process; and 6) the reluctance of employees to admit employment of undocumented aliens. In the end, more than 90% of applicants are expected to be granted temporary resident alien status (and about 70% of agricultural workers), for a total of more than 2 million people. Researchers estimate that 2.5 - 3 million more persons remain in an undocumented status in the US.     

The impact of international migration on fertility: an econometric population model

The authors develop an econometric model to examine the impact of migration on fertility in Greece in the period 1968-1986. In the model, the fertility equation is considered within a simultaneous equation system, and international migration is included as an explanatory factor of both fertility and per capita income. (SUMMARY IN FRE AND SPA)     

Research & clinical practice. Building a nursing research culture

The internalization of clinical nursing research values, norms, and attitudes via orientation and research development, along with the introduction of research tools (artifacts), constitutes the birthing phase of the acculturation process. The development of unit and individual research agendas and the implementation of research rounds illustrates a "bonding phase," in that nurses are bonding or weaving research into the fabric of their clinical practice. The final phase, stabilization, occurs when clinical nursing research is core to clinical nursing practice as illustrated by rewards or sanctions via performance evaluations, and provisions for release time for research participation.     

International law and human rights: trends concerning international migrants and refugees

Not with standing human rights linkages, migrants and refugees are often on the periphery of effective international protection. State sovereignty and self-regarding notions of community are used to deny or dilute substantive and procedural guarantees. Recently, even non- discrimination as a fundamental principle has been questioned, as has the system of refugee protection. This article located both migrants and refugees squarely within the human rights context, contrasting both inalienable rights with the demands of sovereignty, and juxtaposing the 2 in a context of existing and developing international standards. Migration and refugee flows will go on, and the developed world, in particular, must address the consequences - legal, humanitarian, socioeconomic, and cultural. Racism and institutional denials of basic rights daily challenge the common interest. This article shows how the law must evolve, responding coherently to contemporary problems, if the structure of rights and freedoms is to be maintained.