Variation in cancer incidence in northeastern Belgium and southeastern Netherlands seems unrelated to cadmium emission of zinc smelters.

Exposure to cadmium has been established to be carcinogenic for humans by the International Agency for Research on Cancer, but this is mainly based on studies with occupational exposures. The substantial 100 year long emission of cadmium by three zinc smelters in the Kempen area across the Dutch-Belgian border might have affected the incidence of cancer in this region. Following a study of increased risks of lung cancer due to cadmium emission (hazard ratio was 4.2 for high vs. low cadmium exposure areas in that study), we used data from the three regional population-based cancer registries, covering an area with 2.9 million inhabitants. Analyses of observed incidence were carried out for all cancers and cancer of the lung, kidney, bladder, prostate, testis, and breast separately. At the municipality level standardized incidence ratios were calculated and smoothed using a Poisson-gamma or a conditional autoregressive model. To detect clusters and to calculate an observed/expected ratio (O/E ratio) for each cluster a spatial scan statistic was applied. Significantly increased cancer incidence rates were found at a multimunicipality level for female lung cancer (O/E ratio=1.2), male and female bladder cancer (O/E ratio male=1.8, O/E ratio female=1.7), and prostate cancer (O/E ratio=1.3), none of these clusters being located specifically around the area of the zinc smelters. Therefore, the long term emission of cadmium by the zinc smelters in the Kempen area did not seem to lead to an increase in the incidence of all cancers, and lung, kidney, bladder, prostate, testicular, or breast cancer.

Reliability and validity of the short form of the child health questionnaire for parents (CHQ-PF28) in large random school based and general population samples.

STUDY OBJECTIVES: This study assessed the feasibility, reliability, and validity of the 28 item short child health questionnaire parent form (CHQ-PF28) containing the same 13 scales, but only a subset of the items in the widely used 50 item CHQ-PF50. DESIGN: Questionnaires were sent to a random regional sample of 2040 parents of schoolchildren (4-13 years); in a random subgroup test-retest reliability was assessed (n = 234). Additionally, the study assessed CHQ-PF28 score distributions and internal consistencies in a nationwide general population sample of (parents of) children aged 4-11 (n = 2474) from Statistics Netherlands. MAIN RESULTS: Response was 70%. In the school and general population samples seven scales showed ceiling effects. Both CHQ summary measures and one multi-item scale showed adequate internal consistency in both samples (Cronbach's alpha>0.70). One summary measure and one scale showed excellent test-retest reliability (intraclass correlation coefficient >0.70); seven scales showed moderate test-retest reliability (intraclass correlation coefficient 0.50-0.70). The CHQ could discriminate between a subgroup with no parent reported chronic conditions (n = 954) and subgroups with asthma (n = 134), frequent headaches (n = 42), and with problems with hearing (n = 38) (Cohen's effect sizes 0.12-0.92; p<0.05 for 39 of 42 comparisons). CONCLUSIONS: This study showed that the CHQ-PF28 resulted in score distributions, and discriminative validity that are comparable to its longer counterpart, but that the internal consistency of most individual scales was low. In community health applications, the CHQ-PF28 may be an acceptable alternative for the longer CHQ-PF50 if the summary measures suffice and reliable estimates of each separate CHQ scale are not required.