Documents Kristensen, Petter 3 results

"Background
Pesticides are commonly used in agriculture, and previous studies endorsed the need to further investigate the possible association between their use and risk of lymphoid malignancies in agricultural workers.
Methods
We investigated the relationship of ever use of 14 selected pesticide chemical groups and 33 individual active chemical ingredients with non-Hodgkin lymphoid malignancies (NHL) overall or major subtypes, in a pooled analysis of three large agricultural worker cohorts. Pesticide use was derived from self-reported history of crops cultivated combined with crop-exposure matrices (France and Norway) or self-reported lifetime use of active ingredients (USA). Cox regression models were used to estimate cohort-specific hazard ratios (HRs) and 95% confidence intervals (CIs), which were combined using random effects meta-analysis to calculate meta-HRs.
Results
During follow-up, 2430 NHL cases were diagnosed in 316 270 farmers accruing 3 574 815 person-years under risk. Most meta-HRs suggested no association. Moderately elevated meta-HRs were seen for: NHL and ever use of terbufos (meta-HR = 1.18, 95% CI: 1.00–1.39); chronic lymphocytic leukaemia/small lymphocytic lymphoma and deltamethrin (1.48, 1.06–2.07); and diffuse large B-cell lymphoma and glyphosate (1.36, 1.00–1.85); as well as inverse associations of NHL with the broader groups of organochlorine insecticides (0.86, 0.74–0.99) and phenoxy herbicides (0.81, 0.67–0.98), but not with active ingredients within these groups, after adjusting for exposure to other pesticides.
Conclusions
Associations of pesticides with NHL appear to be subtype- and chemical-specific. Non-differential exposure misclassification was an important limitation, showing the need for refinement of exposure estimates and exposure–response analyses."

"Objectives The aim of this study was to (i) construct and evaluate a gender-specific job exposure matrix (JEM) for mechanical and psychosocial work exposures and (ii) test its predictive validity for low-back pain.
Methods We utilized data from the Norwegian nationwide Survey of Living Conditions on work environment in 2006 and 2009. We classified occupations on a 4-digit level based on the Norwegian version of the International Standard Classification of Occupations (ISCO-88). The mechanical and psychosocial exposure information was collected by personal telephone interviews and included exposures that were known risk factors for low-back pain. We evaluated the agreement between the individual- and JEM-based exposure estimates, with kappa, sensitivity and specificity measures. We assessed the JEM`s predictive validity by testing the associations between low-back pain and the individual- and JEM-based exposure.
Results The results showed an overall fair-to-moderate agreement between the constructed JEM and individual work exposures. The JEM performed considerably better for mechanical work exposures compared with psychosocial work exposures. The predictive validity of the mechanical and psychosocial JEM showed a consistently lower but predominantly reproducible association with low-back pain for both genders.
Conclusions The mechanical estimates and psychosocial stressors, such as psychological demands, monotonous work and decision latitude in the constructed JEM, may be useful in large epidemiological register studies. The predictive validity of the matrix was evaluated as being overall acceptable, it can thus be an effective and versatile approach to estimate the relationship between work exposures and low-back pain."

"Objectives
Many women experience absence periods from work during pregnancy. Several single risk factors for absence are identified, whereas the impact of multiple concurrent exposures has been sparsely studied. We hypothesized that the presence of multiple occupational exposures would be associated with an increased risk of absence from work during pregnancy.
Methods
We included women from the Danish National Birth Cohort (1996–2002), pregnant with one child and working ≥30 hours/week at interview (mean gestational week 17 (standard deviation 4.0); N=50 142). Information about five occupational exposures (job demands, job control, work posture, work shift, lifting) were retrieved from the interview, each assigned values of 0/1, and summed into an index (0–5). The woman's first absence from work (both regular and related to pregnancy) after the interview was available from a nationwide administrative register. We analyzed data with Cox regression using gestational age as the underlying time-variable.
Results
Few women experienced none of the occupational exposures (3.6%) and most experienced two exposures (34.7%). Only 24.3% of the women were absent from work before gestational week 31. The number of occupational exposures was associated with an increasing risk of absence. The adjusted hazard ratio for absence increased from 1.3 [95% confidence interval (CI) 1.1–1.5] for one exposure to 2.9 (95% CI 2.5–3.3) for four to five exposures compared to no occupational exposure.
Conclusion
The higher the number of potentially adverse occupational exposures pregnant women experienced, the higher the risk for absence from work during pregnancy."