Residential mobility and the risk of childhood leukemia

Residential mobility and liver cancer risk: findings from a prospective cohort study in Chinese women

BACKGROUND

Residential mobility is believed to influence the occurrence and development of cancer; however, the results are inconclusive. Furthermore, limited studies have been conducted on Asian populations. This study aimed to evaluate the relationship between residential mobility and liver cancer risk among Chinese women.

METHODS

We enrolled 72,818 women from urban Shanghai between 1996 and 2000, and then followed them until the end of 2016. Cox regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) to assess the association between residential mobility and liver cancer risk. A linear trend test was conducted by ranking variables. A sensitivity analysis was also conducted, excluding participants with follow-up times of less than 2 years, to prevent potential bias.

RESULTS

During the 1,269,765 person-years of follow-up, liver cancer was newly diagnosed in 259 patients. Domestic migration (HR = 1.47, 95% CI, 1.44-1.50), especially immigration to Shanghai (HR = 1.47, 95% CI, 1.44-1.50) was associated with an increased risk of liver cancer. In addition, migration frequency, age at initial migration and first immigration to Shanghai had linear trends with an increased liver cancer risk (Ptrend <0.001). The results were similar when excluding participants with less than two years of follow-up.

CONCLUSIONS

The possible association between residential mobility and a higher risk of liver cancer in women could suggest the need for effective interventions to reduce adverse environmental exposures and enhance people's health.

Childhood leukaemia incidence and trends in a Middle Eastern country during 1980-2014: a population-based study

BACKGROUND

This retrospective cohort study examines the trends in childhood leukaemia age-standardized incidence rates (ASIRs) (per million person-years) using cases which were diagnosed at age 0-19 years from 1980 to 2014 and recorded in the Kuwait Cancer Control Center (KCCC) registry.

METHODS

Childhood leukaemia age-specific incidence rates overall and by sub-cohorts defined by age (0-4, 5-9, 10-14, and 15-19 years), sex (male, female) and nationality (Kuwaiti, non-Kuwaiti) were computed and age-standardized. Joinpoint regression models were used to evaluate trends in childhood leukaemia ASIRs. Average annual percent change (AAPC) and its 95% confidence interval (CI) were used to interpret the observed trends.

RESULTS

During the study period, 1077 childhood leukaemia cases of 32.3 million person-years were diagnosed. From 1980 to 2014, the average annual childhood leukaemia ASIR was 53.1 (95% CI 20.9, 85.2). Overall childhood leukaemia ASIRs significantly decreased on average by 6.8% per year (AAPC =  -6.8; 95% CI -12.1, -1.1; p = 0.02) from 1980 to 1993, but a marginally significant increase in ASIRs from 1993 to 2014 was recorded (AAPC = 2.5; 95% CI -0.5, 5.5; p = 0.10). During the entire period, childhood leukaemia ASIRs trends significantly (p < 0.05) increased among 6 of 16 sub-cohorts, which was more pronounced among females and 10-14-year-old children.

CONCLUSIONS

Overall, ASIRs significantly increased from 1993 to 2014, which specifically seems to be driven by an increase in ASIRs among females and 10-14 -year-old children. These increasing trends underscore the potential involvement of a range of exposures. Future studies on unravelling such factors may help develop preventive measures to minimize childhood leukaemia risk in this and similar settings in the region.

Residential mobility and socioemotional and behavioural difficulties in a preschool population cohort of New Zealand children

Background

Findings regarding early residential mobility and increased risk for socioemotional and behavioural (SEB) difficulties in preschool children are mixed, with some studies finding no evidence of an association once known covariates are controlled for. Our aim was to investigate residential mobility and SEB difficulties in a population cohort of New Zealand (NZ) children.

Methods

Data from the Integrated Data Infrastructure were examined for 313 164 children born in NZ since 2004 who had completed the Before School Check at 4 years of age. Residential mobility was determined from address data. SEB difficulty scores were obtained from the Strengths and Difficulties Questionnaire administered as part of the Before School Check.

Results

The prevalence of residential mobility was 69%; 12% of children had moved ≥4 times. A linear association between residential mobility and increased SEB difficulties was found (B=0.58), which remained robust when controlling for several known covariates. Moves >10 km and moving to areas of higher socioeconomic deprivation were associated with increased SEB difficulties (B=0.08 and B=0.09, respectively), while residential mobility before 2 years of age was not. Children exposed to greater residential mobility were 8% more likely to obtain SEB difficulties scores of clinical concern than children exposed to fewer moves (adjusted OR 1.08).

Conclusion

This study found a linear association between residential mobility and increased SEB difficulties in young children. This result highlights the need to consider residential mobility as a risk factor for SEB difficulties in the preschool years.

The Krümmel (Germany) Childhood Leukaemia Cluster: a review and update

The debate surrounding possible adverse health effects from the civil use of nuclear power under normal operating conditions has been on-going since its introduction. It was particularly intensified by the detection of three leukaemia clusters near nuclear installations, i.e. near the reprocessing plants in Sellafield and Dounreay, UK, and near the Krümmel nuclear power plant, Germany, the last of which commenced between 1990 and 1991 and was first described in 1992; it continued until 2003, and an elevated risk up to 2005 has been reported in the literature. A number of expert commissions and working groups were set up by the governments of the German federal states of Lower Saxony and Schleswig-Holstein to investigate the possible causes of the cluster. An overview of the many risk factors that were investigated as a possible explanation of the Krümmel cluster is given here, focussing on radiation, but also including other risk factors. Further, results from related epidemiological and cytogenetic studies are described. In summary, the cause of the occurrence of the Krümmel cluster has to be considered as unknown. Further research on the causes of childhood leukaemia is needed, focussing on epigenetics and on gene-environment interaction. An update of the leukaemia incidence around the Krümmel site shows that the incidence rates are now comparable to the average rate in Germany.

Comparative analyses of studies of childhood leukemia and magnetic fields, radon and gamma radiation

In this paper we compare the findings of epidemiologic studies of childhood leukemia that examined at least two of ELF magnetic fields and/or distance to power lines, and exposure to radon and gamma radiation or distance to nuclear plants. Many of the methodologic aspects are common to studies of non-ionising (i.e. ELF-MF) and ionising radiation. A systematic search and review of studies with more than one exposure under study identified 33 key and 35 supplementary papers from ten countries that have been included in this review. Examining studies that have looked at several radiation exposures, and comparing similarities and differences for the different types of radiation, through the use of directed acyclic graphs, we evaluate to what extent bias, confounding and other methodological issues might be operating in these studies. We found some indication of bias, although results are not clear cut. There is little evidence that confounding has had a substantial influence on results. Influence of the residential mobility on the study conduct and interpretation is complex and can manifest as a selection bias, confounding, increased measurement error or could also be a potential risk factor. Other factors associated with distance to power lines and to nuclear power plants should be investigated. A more complete and consistent reporting of results in the future studies will allow for a more informative comparison across studies and integration of results.

Can changes in population mixing and socio-economic deprivation in Cumbria, England explain changes in cancer incidence around Sellafield?

Previously excesses in incident cases of leukaemia and non-Hodgkin lymphoma have been observed amongst young people born or resident in Seascale, Cumbria. These excesses have not been seen more recently. It is postulated that the former apparent increased risk was related to 'unusual population mixing', which is not present in recent years. This study investigated changes in measures of population mixing from 1951-2001. Comparisons were made between three specified areas. Area-based measures were calculated (migration, commuting, deprivation, population density). All areas have become more affluent, although Seascale was consistently the most affluent. Seascale has become less densely populated, with less migration into the ward and less diversity with respect to migrants' origin. There have been marked changes in patterns of population mixing throughout Cumbria. Lesser population mixing has been observed in Seascale in recent decades. Changes in pattern and nature of population mixing may explain the lack of recent excesses.