Fertility and exposure to solvents among families in the Agricultural Health Study

BACKGROUND

Several studies have reported associations between solvent exposure and reduced female fertility, but the evidence is inconclusive for male fertility.

OBJECTIVES

To investigate the impact of solvent exposure on subfertility among families of male licensed pesticide applicators in the Agricultural Health Study cohort.

METHODS

The couples enrolled between 1993 and 1997. Cross-sectional questionnaire information on work tasks was used to assess exposure to solvents. The data were limited to couples (wife aged less than 40 years) with an attempt at pregnancy in the last four years (n = 2112).

RESULTS

Twenty eight per cent of the couples were defined as subfertile (not conceiving a pregnancy after at least 12 months of unprotected intercourse, regardless of whether or not a pregnancy ultimately occurred). Adjusted subfertility odds ratios (OR) for exposure to solvents were calculated with logistic regression. Female (OR 1.42, 95% CI 1.15 to 1.75) and male exposure to solvents (OR 1.21 (95% CI 0.93 to 1.57) for monthly exposure and 1.40 (95% CI 0.97 to 2.03) for daily or weekly exposure) were associated with subfertility. In farming, spouses may share or exchange jobs. To account for potential dual exposure, variables for parental exposure (either parent exposed or both parents exposed) were also defined. Both were strongly associated with subfertility (OR 1.62 (95% CI 1.20 to 2.17) and OR 2.10 (95% CI 1.22 to 3.60), respectively).

CONCLUSIONS

Solvents may impair fertility of either gender, though the evidence for female effects is stronger than for male effects.

Occupational exposures and non-Hodgkin lymphoma: where do we stand?

Commentary on the paper by Mester et al (see page 17)

High peripheral blood progenitor cell counts enable autologous backup before stem cell transplantation for malignant infantile osteopetrosis

Autosomal recessive osteopetrosis (OP) is a rare, lethal disorder in which osteoclasts are absent or nonfunctional, resulting in a bone marrow cavity insufficient to support hematopoiesis. Because osteoclasts are derived from hematopoietic precursors, allogeneic hematopoietic cell transplantation can cure the bony manifestations of the disorder. However, high rates of graft failure have been observed in this population. It is not possible to harvest bone marrow from these patients for reinfusion should graft failure be observed. We report that 8 of 10 patients with OP had high numbers of circulating CD34(+) cells (3% +/- 0.9%). This increased proportion of peripheral CD34(+) cells made it possible to harvest 2 x 10(6) CD34(+) cells per kilogram with a total volume of blood ranging from 8.3 to 83.7 mL (1.3-11.6 mL/kg). In addition, colony-forming assays documented significantly more colony-forming unit-granulocyte-macrophage and burst-forming unit-erythroid in the blood of osteopetrotic patients compared with controls; the numbers of colony-forming units approximated those found in control marrow. We conclude that OP patients with high levels of circulating CD34(+) are candidates for peripheral blood autologous harvest by limited exchange transfusion. These cells are then available for reinfusion should graft failure be observed in patients for whom retransplantation is impractical.

Disease and injury among participants in the Agricultural Health Study

The Agricultural Health Study (www.aghealth.org) is a cohort of 89,658 pesticide applicators and their spouses from Iowa and North Carolina assembled between 1993 and 1997 to evaluate riskfactorsfor disease in ruralfarm populations. This prospective study is just now reaching sufficient maturity for analysis of many disease endpoints. Nonetheless, several analyses have already provided interesting and important leads regarding disease patterns in agricultural populations and etiologic clues for the general population. Compared to the mortality experience of the general population in the two states (adjusted for race, gender, age and calendar time), the cohort experienced a very low mortality rate overall and for many specific causes and a low rate of overall cancer incidence. A few cancers, however, appear elevated, including multiple myeloma and cancers of the lip, gallbladder, ovary, prostate, and thyroid, but numbers are small for many cancers. A study of prostate cancer found associations with exposure to several pesticides, particularly among individuals with a family history of prostate cancer. Links to pesticides and other agricultural factors have been found for injuries, retinal degeneration, and respiratory wheeze. Methodological studies have determined that information collected by interview is unbiased and reliable. A third round of interviews scheduled to begin in 2005 will collect additional information on agricultural exposures and health outcomes. The study can provide data to address many health issues in the agricultural community. The study investigators welcome collaboration with interested scientists.

A Primitive Cell Origin for B-Cell Precursor ALL?

A stem cell origin has been described for both acute and chronic myelogenous leukemias. In contrast, childhood B-cell precursor acute lymphoblastic leukemia (ALL) is thought to arise in committed B-lineage cells. Recently described in vitro and in vivo model systems that support the proliferation and expansion of ALL cells have provided new tools to investigate the cellular targets for the origin of this malignancy. Evidence suggests that some subtypes of childhood ALL have a primitive cell origin and share many immunophenotypic characteristics with normal progenitor cells. These leukemic stem cells may be resistant to current therapeutic strategies designed to kill the bulk ALL cell population and subsequent relapses may arise from this population. More precise definition of these ALL stem cells through combined analyses of antigen expression, genetic lesions, and functionality is essential for the development of more effective, targeted therapeutic strategies.

The Digital Cytocochleogram

The Mouse Cochlea Database (MCD) is a collection of resources that include digital images and bibliographic information on the mouse cochlea and is available at: http://mousecochlea.ccgb.umn.edu. The purpose of this communication is to report on the development of one MCD resource: the Digital Cytocochleogram. A cytocochleogram is a graphic representation of the anatomical state of the hair cells along the complete width and length of the organ of Corti. The Digital Cytocochleogram provides Internet users with a complete collection of digital images of one or more surface preparations of the mouse organ of Corti from which morphometric information can be obtained. By moving a mouse driven, screen cursor over a digital image, the location and approximate frequency region of the anatomical structure is displayed. Users can also measure the straight-line distance between any two structures on the image. The Digital Cytocochleogram resource uses two software programs, the Coordinate Finder and Viewer, which are written as CGI scripts. The Coordinate Finder program maps each digital image to an X,Y coordinate system. The total length of the organ of Corti from all tissue segments is computed using an arc-distance approximation formula, with the lateral border of the inner pillar cell headplates serving as a trace line or reference location. After all of the digital images of the tissue segments are mapped, they are placed on the MCD Website where users can use the Viewer program to view and morphometrically assess structures using a web browser. A single, complete surface preparation from a normal mouse is presently available on the MCD website. As the MCD grows, additional images of surface preparations at different magnifications from normal, mutant, and experimentally altered mouse cochleas will become available.

Leukaemic stem cells

All haemopoietic cell lineages arise from multipotential self-renewing stem cells that give rise to committed progenitor cells. These progenitor cells subsequently differentiate into more lineage-committed cells with a restricted range of plasticity. A hierarchical order is considered to exist, where lineage commitment and differentiation are thought to be irreversible. As cells differentiate, they gradually lose the ability to self-renew. The most primitive haemopoietic progenitor cells have the ability to reconstitute long-term haemopoiesis in myeloablated recipients. However, as cells differentiate, there is an orchestrated silencing of some genes and activation of others, resulting in lineage commitment and generally a reduction in proliferative ability. Here, we discuss potential differences between normal and leukaemic stem cells, some of which may have therapeutic implications.

Measurement of the consistency of patellar-tendon-bearing cast rectification

The quality of fit of a trans-tibial patellar-tendon-bearing (PTB) socket may be influenced by consistency in casting, rectification or alignment. This paper quantifies, for the first time, the variations in the rectified casts between two experienced prosthetists and the variation between the rectified casts of each individual prosthetist. Prosthetists A and B observed the hand casting of a typical trans-tibial amputee. Each prosthetist was supplied with 5 previously measured duplicated plaster models. The two prosthetists rectified the supplied plaster models based on their own interpretation of basic rectification guidelines. Both prosthetists operated in isolation. The re-measured rectified plaster model data was compared with the unrectified data. The extent of rectification at each of 1800 locations per plaster model was calculated. In zones of major rectification, the mean difference between prosthetists was quantified as 2mm and the standard deviation (SD) about that mean was +/- 1mm for each prosthetist. The co-ordinates of the apex of the fibular head for the 10 modified casts indicated that the maximum variation was in the axial direction with a SD of 4.3mm for prosthetist A and a SD of 2.8mm for prosthetist B. The lengths of the 5 plaster models rectified by prosthetist A indicated a SD of 0.2mm whereas the lengths of the 5 plaster models rectified by prosthetist B indicated a SD of 2.9mm.

Integrative assessment of multiple pesticides as risk factors for non-Hodgkin's lymphoma among men

BACKGROUND

An increased rate of non-Hodgkin's lymphoma (NHL) has been repeatedly observed among farmers, but identification of specific exposures that explain this observation has proven difficult.

METHODS

During the 1980s, the National Cancer Institute conducted three case-control studies of NHL in the midwestern United States. These pooled data were used to examine pesticide exposures in farming as risk factors for NHL in men. The large sample size (n = 3417) allowed analysis of 47 pesticides simultaneously, controlling for potential confounding by other pesticides in the model, and adjusting the estimates based on a prespecified variance to make them more stable.

RESULTS

Reported use of several individual pesticides was associated with increased NHL incidence, including organophosphate insecticides coumaphos, diazinon, and fonofos, insecticides chlordane, dieldrin, and copper acetoarsenite, and herbicides atrazine, glyphosate, and sodium chlorate. A subanalysis of these "potentially carcinogenic" pesticides suggested a positive trend of risk with exposure to increasing numbers.

CONCLUSION

Consideration of multiple exposures is important in accurately estimating specific effects and in evaluating realistic exposure scenarios.

Pilot study: data-capturing consistency of two trans-tibial casting concepts, using a manikin stump model: a comparison between the hands-on PTB and hands-off ICECAST compact concepts

The quality of fit of a trans-tibial patellar tendon bearing (PTB) socket may be influenced by consistency in casting, rectification or alignment. For this study two distinctive different data-capturing concepts were tested in relation to prosthetist performance. The hands-on PTB and hands-off ICECAST compact concept were studied and compared for inter- and intra-prosthetist consistency using a specially designed manikin stump model. A purpose designed digitiser was used to scan a selected surface area of the produced models, 5 for each concept, 10 in total. The extent of casting consistency at each of 936 locations per plaster model was calculated and the level of consistency was quantified. This study has shown that by using the manikin model there is a clear indication that the investigated hands-off concept produces more consistent results than the hands-on concept.

Impact on T-cell depletion and CD34+ cell recovery using humanised CD52 monoclonal antibody (CAMPATH-1H) in BM and PSBC collections; comparison with CAMPATH-1M and CAMPATH-1G

BACKGROUND

Ex vivo T-cell depletion of allogeneic BM (BM) grafts can effectively reduce graft versus host disease (GvHD) and may also apply to transplantation of allogeneic peripheral blood stem cell (PBSC) transplants.

METHODS

Here we have evaluated T-cell depletion and progenitor cell recovery by antibody-mediated cells lysis using three CD52 monoclonal antibodies (MAbs) at different concentrations and cell densities.

RESULTS

CAMPATH-1M was superior to CAMPATH-1H for T-cell depletion of BM samples. Treatment with CAMPATH-1M resulted in up to 2.55 log depletion of CD3+ cells, with recoveries of >or=45% CD34+ cells, >or=67% CFU-GM and >or=65% BFU-E. CAMPATH-1H treatment resulted in up to 1.64 log depletion of CD3+ cells and similar recoveries of CD34+ cells, CFU-GM and BFU-E as seen with CAMPATH-1M. Depletion of CD19+ cells was similar to that observed for CD3+ cells while natural killer (NK) cells were relatively spared compared with the T and B cell populations. Log depletions of T cells from PBSC, as determined by immunofluorescence studies and limiting dilution analyses, were similar using CAMPATH-1M, -1H, and -1G. There were also no differences in the depletion of CD19+ cells or NK cells using the three MAbs. Similar results were obtained for recoveries of CD34+ cells, CFU-GM and BFU-E using all three MAbs, although the recovery of CD34+ cells using the highest concentration of MAbs was significantly greater in CAMPATH-1H treated samples. Increasing the number of PBSC treated with CAMPATH-1H and -1M had no effect on the log depletion of T, B or NK cells and there were no major differences in the log depletions achieved with CAMPATH-1H or -1M. Likewise, the higher PBSC density had no effect on the recoveries of CD34+ cells or committed progenitors and once again CAMPATH-1H gave similar recoveries to those obtained using CAMPATH-1M.

DISCUSSION

Although CAMPATH-1M resulted in greater ex vivo T-cell depletion of BM than CAMPATH-1H, in all other respects, the humanised CAMPATH-1H was just as effective as CAMPATH-1M and -1G.

Serum levels of beta-hexachlorocyclohexane, hexachlorobenzene and polychlorinated biphenyls and breast cancer in Mexican women

Information on the association between exposure to beta-hexachlorocyclohexane (beta-HCH), hexachlorobenzene (HCB) or polychlorinated biphenyls (PCBs) and the incidence of breast cancer is inconclusive. However, exposure to such compounds is a public health concern in Mexico and is subject to recent regulation. Serum levels of beta-HCH, HCB and PCBs were analysed in 95 histologically confirmed breast cancer cases and 95 hospital controls, 20-79 years of age, from Mexico City, enrolled between March 1994 and April 1996. After adjusting for established risk factors, there was no evidence of a relationship between beta-HCH, HCB and PCBs and breast cancer risk (OR for beta-HCH tertile 3 versus tertile 1: 1.05 95% CI 0.46-2.40; OR for HCB tertile 3 versus tertile 1: 0.46 95% CI 0.20-1.07; OR for PCBs 1.31 95% CI 0.33-5.21 for the high category of exposure). This study lends no support to the case for a role for beta-HCH, HCB or PCBs in breast cancer aetiology.

A case-control study of tobacco use and other non-occupational risk factors for t(14;18) subtypes of non-Hodgkin's lymphoma (United States)

OBJECTIVE

Non-Hodgkin's lymphoma (NHL) encompasses diverse subtypes, and analyzing NHL as a single outcome may mask associations. In a new approach we evaluated associations with subtypes defined by the t(14;18) translocation, reasoning that cases within these subtypes would have more common risk factors than all NHL combined.

METHODS

Archival biopsies from cases in a population-based NHL study were assayed for t(14;18) using polymerase chain reaction amplification. Exposures in 68 t(14;18)-positive and 114-negative cases were compared with 1245 controls. The expectation-maximization algorithm was used to fit polytomous regression models based on all available information, including data from 440 unclassified cases.

RESULTS

Family history of hemolymphatic cancer was associated with t(14;18)-negative NHL (odds ratio (OR) 2.4, 95% confidence interval (CI) 1.4 3.9). but not t(14;18)-positive NHL. Cigarette smoking was weakly associated with t(14;18)-positive NHL (OR 1.7, CI 0.9-3.3), but ORs decreased as smoking increased. Chewing tobacco was associated with t(14;18)-positive NHL, particularly when used before age 18 (OR 2.5. CI 1.0-6.0, 13 exposed cases). Odds ratios for both case-subtypes were doubled among hair-dye users.

CONCLUSIONS

Cigarette smoking was not clearly associated with t(14;18)-positive NHL. Family history may be a marker for factors that act specifically through t(14;18)-negative pathogenic mechanisms.

Development of a life events/icon calendar questionnaire to ascertain occupational histories and other characteristics of migrant farmworkers

BACKGROUND

Specialized methods are necessary to collect data from migrant farmworkers for epidemiologic research.

METHODS

We developed a questionnaire that collected lifetime occupational histories and other lifestyle risk factors via a life events/icon calendar, and administered the questionnaire to a convenience sample of 162 migrant farmworkers in nine areas of the U.S.

RESULTS

The average duration of the interviews was about 1 h 30 min, with an average of 45 min for the work history section. The occupational histories covered a median of 27.6 years per person for men and 20.8 years per person for women. The median number of years spent in farm jobs was 11.3 for men and 5.8 for women. The median number of farm jobs (crop/task combination) per person was 59 among men and 27 among women. Many farmworkers performed the same crop/task combinations at multiple times throughout their lives, yielding a median of 13 unique farm jobs and 8 unique crops among men and 7 jobs and 5 crops among women.

CONCLUSIONS

The project demonstrated that it is feasible to collect detailed work histories and other risk factor data from farmworkers, documented the complexity of work histories encountered among farmworkers, and yielded recommendations for refining a questionnaire that will facilitate future epidemiologic research on farmworkers.