Workforce Characteristics and Attitudes Regarding Participation in Worksite Wellness Programs.

PURPOSE: To estimate workforce participation characteristics and employees' attitudes regarding participation in workplace wellness programs. DESIGN: Data from a statewide stratified random sample were used to compare small (<50 employees) and larger (50+ employees) workplaces to estimate participation in screening programs and likelihood of participation in workplace wellness programs. SETTING: A telephone survey of employed Iowans registered to vote. SUBJECTS: Surveyed were 1171 employed Iowans registered to vote, ages 18 to 65. MEASURE: Among questionnaire survey modules were items from the Wellness Council of America Employee Needs and Interest Survey, the U.S. Census Bureau for employment documentation, and the World Health Organization Health and Work Performance Questionnaire for assessment of sickness absenteeism and presenteeism. ANALYSIS: Prevalence of participation in screening and wellness programs was analyzed by employment size and levels of likeliness to participate, and multivariable analyses of employee baseline characteristics regarding participation in screening programs and likelihood of participation in wellness programs was presented as top and bottom quartiles. RESULTS: Those employed in smaller workplaces participated less often in screening programs. Multivariable models identified male gender and those with an abnormal body mass index were associated with nonparticipation, while having a primary care physician was associated with participation. Very few items showed significant statistical difference in willingness to participate. CONCLUSION: Workforce characteristics and access to health care may influence participation in screening and wellness programs. Employment size is not a determining factor for willingness to participate in wellness programs.

Employment status matters: a statewide survey of quality-of-life, prevention behaviors, and absenteeism and presenteeism.

OBJECTIVE: To estimate quality-of-life (QoL), primary care, health insurance, prevention behaviors, absenteeism, and presenteeism in a statewide sample of the unemployed, self-employed, and organizationally employed. METHODS: A statewide survey of 1602 Iowans included items from the Centers for Disease Control and Prevention QoL and Behavioral Risk Factor Surveillance System Survey prevention behavior questionnaires used to assess employee well-being; their indicator results are related to World Health Organization's Health and Work Performance Questionnaire-derived absenteeism and presenteeism scores. RESULTS: The unemployed exhibited poorer QoL and prevention behaviors; the self-employed exhibited many better QoL scores due largely to better prevention behaviors than those employed by organizations. Higher QoL measures and more prevention behaviors are associated with lower absenteeism and lower presenteeism. CONCLUSIONS: Employment status is related to measures of well-being, which are also associated with absenteeism and presenteeism.

The numbers game: evaluation of statistics by obstetrics & gynecology.

Statistical analysis has become integral to the planning, conduct, and reporting of modern medical research. Attention to the statistical aspects of manuscripts submitted to Obstetrics & Gynecology goes back approximately 40 years and the process used in their evaluation has evolved over that time. For the past 20 years, submissions with any type of statistics and being seriously considered for acceptance have routinely been reviewed by a Statistical Editor who judges the work on a number of statistical and design characteristics. Findings of the statistical design review (which has been done by one Statistical Editor over the entire 20-year period) are integrated into the editorial decision about acceptance. The statistical review generally leads to rejection of approximately 16-25% of manuscripts and in a larger proportion, it identifies less serious problems, the correction of which improves the final product.

At what age should children engage in agricultural tasks?

PURPOSE: We compared parents' perceived-as-appropriate ages with actual-performance ages for their children engaging in selected agricultural tasks or practices, and we examined the factors associated with age discrepancy. METHODS: We analyzed data from the Keokuk County Rural Health Study collected among parents of children age 17 or younger. Parents were interviewed separately regarding the age of their children's involvement in 14 selected agricultural tasks and their opinions about appropriate age of involvement. FINDINGS: Of the 264 families included, 86.5% with a son and 69.8% with a daughter reported having children involved in at least 1 of 14 selected agricultural tasks. The average actual-performance ages for children to be involved in any of the tasks were younger than those that parents perceived appropriate. Furthermore, in 6 of the 9 North American Guidelines for Children's Agricultural Tasks (NAGCAT) that we assessed, parents' perceived-as-appropriate ages were younger than minimum ages recommended by the NAGCAT. Driving an all-terrain vehicle (ATV) was the most common task with actual-performance age younger than the NAGCAT-recommended age; 53.0% of boys (n = 106) and 36.1% of girls (n = 61) did so under the recommended age. Boys and children who live on a farm, or whose parents have been or are farmers, were significantly more likely to perform agricultural tasks at earlier ages. CONCLUSIONS: Our results suggest farm parents and other rural stakeholders need to be better educated and encouraged to follow the NAGCAT guidelines, and that multilevel interventions need to be developed to ensure protection of children from agricultural injury and death.

Accelerated removal of antibody-coated red blood cells from the circulation is accurately tracked by a biotin label.

BACKGROUND: Safe, accurate methods to reliably measure circulating red blood cell (RBC) kinetics are critical tools to investigate pathophysiology and therapy of anemia, including hemolytic anemias. This study documents the ability of a method using biotin-labeled RBCs (BioRBCs) to measure RBC survival (RCS) shortened by coating with a highly purified monomeric immunoglobulin G antibody to D antigen. STUDY DESIGN AND METHODS: Autologous RBCs from 10 healthy D+ subjects were labeled with either biotin or (51) Cr (reference method), coated (opsonized) either lightly (n = 4) or heavily (n = 6) with anti-D, and transfused. RCS was determined for BioRBCs and for (51) Cr independently as assessed by three variables: 1) posttransfusion recovery at 24 hours (PTR(24) ) for short-term RCS; 2) time to 50% decrease of the label (T(50) ), and 3) mean potential life span (MPL) for long-term RCS. RESULTS: BioRBCs tracked both normal and shortened RCS accurately relative to (51) Cr. For lightly coated RBCs, mean PTR(24) , T(50) , and MPL results were not different between BioRBCs and (51) Cr. For heavily coated RBCs, both short-term and long-term RCS were shortened by approximately 17 and 50%, respectively. Mean PTR(24) by BioRBCs (84 ± 18%) was not different from (51) Cr (81 ± 10%); mean T(50) by BioRBCs (23 ± 17 days) was not different from (51) Cr (22 ± 18 days). CONCLUSION: RCS shortened by coating with anti-D can be accurately measured by BioRBCs. We speculate that BioRBCs will be useful for studying RCS in conditions involving accelerated removal of RBCs including allo- and autoimmune hemolytic anemias.

Red blood cell (RBC) volume can be independently determined in vivo in humans using RBCs labeled at different densities of biotin.

BACKGROUND: Anemia is a serious problem in critically ill neonates. To investigate the pathophysiology of anemia and responses to red blood cell (RBC) transfusions and erythropoietin therapy, repeated measurement of red blood cell volume (RCV) and blood volume is useful. To extend our previous sheep study in which RBCs were labeled at four different biotin densities, we assessed the validity of this multidensity method for in vivo measurement of circulating RCV in humans. STUDY DESIGN AND METHODS: In eight healthy adults, autologous RBCs were biotinylated at each of four biotin densities (6, 18, 54, and 162 µg biotinylation reagent/mL RBC), mixed, and infused intravenously; blood was sampled at 10, 20, and 60 minutes. At each time, RCV was calculated from dilution of individual RBC populations enumerated by flow cytometry. RCV measurements from the population of RBCs biotinylated at 6 µg/mL were chosen as the reference values because this density had been previously validated against the 51Cr method in vitro and in vivo in humans. RESULTS: Values for RCVs were not significantly different among the four densities of biotinylated RBCs at any of the three time points and did not change over 60 minutes. CONCLUSIONS: These studies provide evidence that four densities of biotinylated RBCs can be used in vivo for simultaneous, independent, accurate measurements of RCV in humans. We speculate that this method will also be useful for repeated measurement of RCV and blood volume in infants and other patient populations in whom radioactive labels should be avoided.

Red blood cell (RBC) volume can be independently determined in vivo in the sheep using ovine RBCs labeled at different densities of biotin.

BACKGROUND: To investigate the pathophysiology of anemia and responses to red blood cell (RBC) transfusions and erythropoietin, repeated measurement of the circulating red blood cell volume (RCV) would be useful. Ovine erythropoiesis is similar to human erythropoiesis. Accordingly, a method for measuring RCV using either human or sheep RBCs labeled at different biotin densities has been previously validated in vitro. Here preclinical studies validating this method for in vivo measurement of circulating RCV in sheep are reported. STUDY DESIGN AND METHODS: For each sheep, autologous RBCs were biotinylated were at four discrete densities (12, 24, 48, and 96µg biotinylation reagent/mL RBCs). The densities were mixed and infused intravenously. Blood was sampled five times over 1 hour beginning at 4 minutes. RCV values were determined based on dilution of each population of biotinylated RBCs and by the [(14) C]cyanate method. RESULTS: There was no difference among RCVs measured at all densities through 16 minutes; however, by 60 minutes, RBCs biotinylated at the highest density overestimated RCV by 7.6%. RCV values increased 41% over the hour, consistent with equilibration with a pool of RBCs sequestered in the spleen. RCV by the [(14) C]cyanate method paralleled results by the biotin method but averaged 8% greater. CONCLUSIONS: These studies provide evidence that all four densities of biotinylated RBCs can be used in sheep to simultaneously and independently determine RCV. We speculate that the multidensity biotinylation method will be useful both for multiple simultaneous measurements and for repeated measurement of circulating RCV and blood volume in humans.

Challenges of conducting a large rural prospective population-based cohort study: the Keokuk County Rural Health Study.

The Keokuk County Rural Health Study (KCRHS) is a population-based, prospective study of health status and environmental exposures of a large stratified random sample of residents in one rural Iowa county. The study focuses on injury and respiratory disease and monitors health care delivery, geriatric health, mental health, and other health outcomes, as well as behavioral risk factors for disease and injury. Injury and disease prevalence is investigated in relation to occupational, agricultural, and other environmental exposures. The KCRHS enrolled 1004 families in Round 1 (1994 to 1998) and 1002 families in Round 2 (1999 to 2004). Participants range in age from newborn to 98 years of age and are about equally divided between males and females. The families live in farm, rural nonfarm, and town households, representing men, women, and children, the elderly, farmers, and nonfarmers. The KCRHS is currently in Round 3 (2006-2011). Although the sample is stratified by residence type, the entire county is, by definition, rural, because the largest town has fewer than 2500 residents. Using the Keokuk County Rural Health Study as an example, this paper describes the methodological challenges faced in conducting a large rural prospective population-based cohort study. Some of these challenges are inherent in any large cohort study; others are unique to rural cohort studies. Topics considered include planning the study, developing the protocol, sampling, recruiting and tracking subjects, data collection and management, sustaining funding, relating to the community, and sharing data.

Red blood cell volume can be independently determined in vitro using sheep and human red blood cells labeled at different densities of biotin.

BACKGROUND: The development of valid methods for repeatedly measuring red blood cell (RBC) volume (RCV) in the same individual would be useful in furthering understanding of the physiology and pathophysiology of the pregnant woman, fetus, and infant under a variety of conditions. STUDY DESIGN AND METHODS: Small volumes (5 to 100 mL) of either sheep or human blood were used to test the hypothesis that there is no significant difference in RCV and blood volume determined in vitro using as many as five populations of RBCs labeled at distinct biotin densities. By varying the mass of biotinylating reagent, the density of biotin on the surface of RBCs was incrementally increased to produce discrete populations as assessed by flow cytometric enumeration. Calculation of RCV for each biotin-labeled RBC population was based on the dilution principle. RESULTS: All biotin densities, except the most densely labeled, where variance was the greatest, accurately quantitated the in vitro blood volume to within 10 percent of the correct value. There was no bias of either overestimation or underestimation in the determination of the blood volume using either sheep or human RBCs. CONCLUSION: These in vitro results provide evidence that the multidensity biotin labeling method is sufficiently accurate to utilize in vivo for repeated determination of circulating RCV and blood volume.

Farm activities associated with eye injuries in the Agricultural Health Study.

Farmers are at risk for work-related eye injuries, some of which can be very serious. This study describes the farm activities that were related to eye injury in a group of 36 Iowa farmers in the Agricultural Health Study who sustained 40 farmwork-related eye injuries requiring medical advice or treatment. Farm activities of grinding or cutting metal accounted for 11 (27.5%) of the eye injuries, welding for 3 (7.5%), and drilling for 2 (5%). The other 24 eye injuries were related to diverse farm activities. One injury was caused by an animal. Only one injury was caused by a chemical exposure. Foreign body in the eye was the most frequent type of eye injury overall, accounting for 32 (80%) of the eye injuries. Of those, 20 were metallic foreign bodies. Although none of the injuries required hospitalization, 10 eye injuries (25%) resulted in the farmer missing 1 to 5 days of work. At least three injuries occurred while farmers were wearing safety glasses/goggles. These results suggest that farmers are at risk for eye injury from activities such as grinding and cutting metal, welding, and drilling and from other diverse activities on the farm for which eye hazards may not have been anticipated. In addition, these findings have implications for use of appropriate eye protection during all farm activities.

Red cell volume can be accurately determined in sheep using a nonradioactive biotin label.

The sheep has served as an informative animal model for investigation of human fetal and newborn erythropoiesis and red blood cell (RBC) kinetics. We previously validated the permanent label (14C)cyanate for measuring red cell volume (RCV) in sheep. Here, we validate biotin labeling of RBCs as a nonradioactive method for measuring RCV in sheep with the anticipation that it can be applied in studies of human infants. The RCV was determined simultaneously using two techniques for quantitation of the biotin label. The first one quantified total blood concentration of biotin label on biotin-labeled RBCs using (125I)streptavidin. The second one enumerated biotin-labeled RBCs by flow cytometry after incubation with fluorescein-conjugated avidin. RCV measurements made using the two biotin quantitation techniques were validated against both (14C)cyanate and 51Cr as reference methods. Both biotin techniques produced RCV values that agreed well with the reference methods and with each other, producing correlation coefficients averaging >or =0.93. Sequential repetitive measurements in the same animal also agreed with the (14C)cyanate method and each other (average difference <10%). These results establish biotin-labeled RBCs as an accurate method for performing RCV measurements in sheep. This biotin method can be applied in studies that model neonatal erythropoiesis.

A randomized clinical trial comparing immediate versus delayed clamping of the umbilical cord in preterm infants: short-term clinical and laboratory endpoints.

BACKGROUND: Most neonates less than 1.0 kg birth weight need red blood cell (RBC) transfusions. Delayed clamping of the umbilical cord 1 minute after delivery transfuses the neonate with autologous placental blood to expand blood volume and provide 60 percent more RBCs than after immediate clamping. This study compared hematologic and clinical effects of delayed versus immediate cord clamping. STUDY DESIGN AND METHODS: After parental consent, neonates not more than 36 weeks' gestation were randomly assigned to cord clamping immediately or at 1 minute after delivery. The primary endpoint was an increase in RBC volume/mass, per biotin labeling, after delayed clamping. Secondary endpoints were multiple clinical and laboratory comparisons over the first 28 days including Score for Neonatal Acute Physiology (SNAP). RESULTS: Problems with delayed clamping techniques prevented study of neonates of less than 30 weeks' gestation, and 105 neonates 30 to 36 weeks are reported. Circulating RBC volume/mass increased (p = 0.04) and weekly hematocrit (Hct) values were higher (p < 0.005) after delayed clamping. Higher Hct values did not lead to fewer RBC transfusions (p > or = 0.70). Apgar scores after birth and daily SNAP scores were not significantly different (p > or = 0.22). Requirements for mechanical ventilation with oxygen were similar. More (p = 0.03) neonates needed phototherapy after delayed clamping, but initial bilirubin levels and extent of phototherapy did not differ. CONCLUSIONS: Although a 1-minute delay in cord clamping significantly increased RBC volume/mass and Hct, clinical benefits were modest. Clinically significant adverse effects were not detected. Consider a 1-minute delay in cord clamping to increase RBC volume/mass and RBC iron, for neonates 30 to 36 weeks' gestation, who do not need immediate resuscitation.

Keokuk County rural health study: self-reported use of agricultural chemicals and protective equipment.

The Keokuk County Rural Health Study is a population-based study of an agricultural community in Iowa. The study includes in-depth evaluations of respiratory disease, injury, and other health outcomes in relation to environmental and occupational exposures. This article reports descriptive findings on pesticide use from among the 1191 participants completing occupational surveys. Fifty-one percent (612) of respondents (farmers and non-farmers) had applied insecticides including lawn and garden chemicals at home during the past year. Thirty-three percent (395) of respondents had personally mixed or applied farm chemicals during their life. One-hundred and four had a current pesticide applicator's license. Information on the specific types of pesticides and protective measures used was obtained for the 144 individuals who had mixed or applied pesticides on farms within the previous year. Of these individuals, 67% worked with fertilizers, 49% used herbicides, 48% used crop insecticides, 28% used crop storage insecticides, 45% applied livestock insecticides, and 9% worked with fungicides. The use of personal protective equipment such as gloves, aprons, and respirators varied depending on the chemical. A substantial proportion did not use gloves even for mixing. Thirty-five percent reported at least one suspected work-related symptom after working with pesticides during the previous year. The lack of differences in protective equipment use between applicators who have completed pesticide applicator training courses and those who have not suggests a need to develop more effective training methods. The increased use of protective equipment when applying odorous agrochemicals suggests that addition of an odorant to more toxic pesticides may be a successful intervention strategy.

Sleep duration and body mass index in a rural population.

BACKGROUND: A growing body of epidemiological evidence suggests an association between short sleep duration and obesity. Recently, potential hormonal links have been observed that may account for the relationship. The possible connection between sleep duration and body mass index (BMI) has not been explored in rural populations. Rural populations are of interest because obesity rates are high and lifestyle patterns of nutrition, physical activity, work hours, and sleep may differ from those in urban and suburban populations. We conducted this study to determine whether short sleep duration is related to BMI and obesity in a rural population in southeast Iowa. METHODS: We conducted a cross-sectional analysis of data collected in the Keokuk County Rural Health Cohort Study, 1999-2004. Study participants were from a population-based sample consisting of 990 employed adults in a rural community in southeastern Iowa. The main outcome measure was BMI. Multiple linear regression modeling was used to adjust for potential confounding variables. RESULTS: Self-reported sleep duration on weeknights was negatively correlated (beta = -0.42; 95% confidence interval, -0.77 to -0.07) with higher BMI after adjusting for sex, age, educational achievement, physical job demand, household income, depressive symptoms, marital status, alcohol consumption, and snoring. CONCLUSION: These data support an association between short sleep duration and higher BMI in this rural population, which is consistent with the relationship found in other settings.

Effects of premium discount on workers' compensation claims in agriculture in Finland.

BACKGROUND: The objective of this study was to measure changes in injury claim rates after a premium discount program was implemented in the Finnish farmers' workers' compensation insurance. We focused on measures that could indicate whether the changes occurred in the true underlying injury rate, or only in claims reporting. METHODS: Monthly injury claim rates were constructed at seven disability duration levels from January 1990 to December 2003. We conducted interrupted time series analyses to measure changes in the injury claim rates after the premium discount was implemented on July 1, 1997. Three additional policy change indicators were included in the analyses. RESULTS: The overall injury claim rate decreased 10.2%. Decreases occurred at four severity levels (measured by compensated disability days): 0 days (16.3%), 1-6 days (14.1%), 7-13 days (19.5%), and 14-29 days (8.4%). No changes were observed at higher severity levels. Minor injuries had a seasonal pattern with higher rates in summer months while severe injuries did not have a seasonal pattern. CONCLUSIONS: The premium discount decreased the overall claim rate. Decreases were observed in all categories up to 29 disability days. This pattern suggests that under-reporting contributes to the decrease but may not be the only factor. The value of the premium discount is lower than the value of a lost-time claim, so there was no financial reason to under-report lost-time injuries. Under-reporting would be expected to be greatest in the 0 day category, but that was not the case. These observations suggest that in addition to under-reporting, the premium discount may also have some preventive effect.

Prevalence of hearing impairment in a rural midwestern cohort: estimates from the Keokuk county rural health study, 1994 to 1998.

OBJECTIVE: The current paper estimates the prevalence of hearing problems in a rural population, analyzes the prevalence of hearing problems across age groups, and compares the prevalence of hearing problems in this population with results obtained in other populations. DESIGN: Data were obtained from a random sample of the residents of a rural county, stratified by farm, rural non-farm, and town residence. Hearing test results were obtained from participants between the ages of 8 and 92 years (N = 1972; 47% male). Pure-tone thresholds were classified as normal or impaired using a number of metrics, including speech intelligibility index values. Selected comparisons of crude rates were made with previous population-based studies of hearing loss prevalence. RESULTS: Nearly all (99%) of the participants in this study had significant hearing impairment. Atypical hearing impairment is most prevalent at 6 kHz. In males, this excess impairment shifts to lower frequencies with age but monotonically decreases in females. Notched configurations were most common among those between 30 and 59 years old. In females, the prevalence of hearing impairments sufficient to interfere with speech understanding begins to rapidly increase in the 6th decade (4th decade in males). Comparisons with prior population-based studies in the United States and Great Britain identified few significant differences. CONCLUSIONS: Significant hearing impairment is common in rural populations. The high prevalence in this population is similar to that found in other population-based studies. Future studies are needed to examine (1) the risk factors for hearing impairment, (2) the natural course of hearing problems across the life span, and (3) the effect of programs for the prevention of hearing impairment and rehabilitation for persons with existing hearing impairments.

Asthma and farm exposures in a cohort of rural Iowa children.

Epidemiologic studies of farm children are of international interest because farm children are less often atopic, have less allergic disease, and often have less asthma than do nonfarm children--findings consistent with the hygiene hypothesis. We studied a cohort of rural Iowa children to determine the association between farm and other environmental risk factors with four asthma outcomes: doctor-diagnosed asthma, doctor-diagnosed asthma/medication for wheeze, current wheeze, and cough with exercise. Doctor-diagnosed asthma prevalence was 12%, but at least one of these four health outcomes was found in more than a third of the cohort. Multivariable models of the four health outcomes found independent associations between male sex (three asthma outcomes), age (three asthma outcomes), a personal history of allergies (four asthma outcomes), family history of allergic disease (two asthma outcomes), premature birth (one asthma outcome), early respiratory infection (three asthma outcomes), high-risk birth (two asthma outcomes), and farm exposure to raising swine and adding antibiotics to feed (two asthma outcomes). The high prevalence of rural childhood asthma and asthma symptoms underscores the need for asthma screening programs and improved asthma diagnosis and treatment. The high prevalence of asthma health outcomes among farm children living on farms that raise swine (44.1%, p = 0.01) and raise swine and add antibiotics to feed (55.8%, p = 0.013), despite lower rates of atopy and personal histories of allergy, suggests the need for awareness and prevention measures and more population-based studies to further assess environmental and genetic determinants of asthma among farm children.

Cost of compensated injuries and occupational diseases in agriculture in Finland.

Although agriculture is one of the most hazardous industries, the costs of agricultural injuries and illnesses are not well known. This study aimed to determine the cost burden from compensated injuries and occupational diseases in Finnish agriculture using workers compensation records. The incidence rates in 1996 were 7.4/100 for injuries and 0.61/100 for occupational diseases. Men had a higher risk of injury (RR = 1.89; 95% CI: 1.81-1.97), but a lower risk of an occupational disease (RR = 0.68; 95% CI: 0.60-0.78), compared to women. The total cost burden was 75 (Euros) per person in 1983, increasing to 215 in 1999. The total insurance cost in 1996 was 23.5 million consisting of medical care (16%), per diem (lost time compensation within one year from the incident) (37%), pension (lost time compensation after one year from the incident) (23%), survivors pension (3%), impairment allowance (7%), rehabilitation (6%), and other costs (9%). The total cost was 0.7% of the national gross farm income and 2.2% of the net farm income. The mean cost of 1996 cases was 1340 for injuries and 6636 for occupational diseases. Injuries represented 92% of the claims and 71% of the total costs. Occupational diseases represented 8% of the claims and 29% of the costs. Twenty percent of the most severe claims represented 79.5% of the total insurance costs. Injuries and occupational diseases result in significant costs in agriculture. Lost time was the largest cost item. Overall, injuries were more costly than occupational diseases. This study indicates that the 20%-80% rule applies to agricultural injury and illness costs, and from the cost standpoint, it is important to focus prevention efforts on the most severe incidents.

Agricultural pesticide use, familial cancer, and risk of non-Hodgkin lymphoma.

To investigate whether the association between agricultural pesticide use and the risk of non-Hodgkin's lymphoma (NHL) is modified by a family history of hematopoietic cancer, including leukemia, myeloma, and lymphoma, we analyzed pooled data on white men from three population-based, case-control studies of NHL conducted in Iowa/Minnesota, Kansas, and Nebraska. Information on the agricultural use of insecticides, fungicides, and herbicides; a family history of cancer; and other risk factors was obtained by interviewing 973 cases and 2,853 controls or, if deceased, their next-of-kin (37% of cases, 43% of controls). The NHL risk was estimated by odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age, state of residence, type of respondent, and use of hair dye. Compared to men with no family history of cancer, the ORs (95% CIs) of NHL was 1.5 (1.3-1.8) for men with a family history of nonhematopoietic cancer, and 2.7 (1.9-3.7) for those with a history of hematopoietic cancer among first-degree relatives. This positive association was noted for each group of NHL defined according to the Working Formulation, and was most pronounced for small lymphocytic NHL. Among direct respondents, farmers who used pesticides and had a positive family history of cancer or hematopoietic cancer were not at elevated risk of NHL, compared to nonfarmers who had no family cancer history. However, among proxy respondents, ORs were elevated for farmers who had a positive family history of hematopoietic cancer and used animal insecticides (OR = 4.6; 1.9-11.2), crop insecticides (OR = 4.7; 1.6-13.4), or herbicides (OR = 4.9; 1.7-14.2), although the interaction of family history of cancer and agricultural pesticide use was not statistically significant. In summary, the joint effects of the family cancer history and pesticide use were limited to proxy respondents with wide CIs and, thus, provide little evidence that a family history of cancer modifies the association of agricultural exposures with NHL.

RBCs labeled at two biotin densities permit simultaneous and repeated measurements of circulating RBC volume.

BACKGROUND: The extend potential applications of a nonradioactive method for measuring circulating RBC volume, we tested the hypothesis that RBC volume could be determined independently using two populations of RBCs labeled with low-density biotin (LDB1) and high-density biotin (HDB). STUDY DESIGN AND METHODS: In 10 healthy adults, autologous RBCs were labeled with HDB, LDB, or 51Cr. The labeled RBCs were mixed and transfused. RBC volume was measured in postinfusion peripheral venous blood by quantitating dilution of each population of labeled RBCs. RESULTS: RBC volume measured using either LDB or HDB cells agreed well with RBC volume measured using 51Cr. For the regression of RBC volume by LDB versus RBC volume by 51Cr, correlation = 0.994 and slope = 0.933. For HDB versus 51Cr, correlation = 0.982 and slope = 0.953. RBC volume measured a second time in four subjects with HDB agreed well; mean CV for the differences between HDB and 51Cr were less than 5 percent. CONCLUSIONS: Using RBCs labeled with two different densities of biotin, RBC volume can be accurately measured simultaneously and repeatedly in the same subject without radiation exposure.