A hierarchical modelling approach for measuring reliability of and agreement between two types of magnetic field dosimeter

The paper describes how to use hierarchical models to assess the reliability of and agreement between two or more types of measurement device. The idea is illustrated by fitting a linear model with nested random effects to a set of data that was obtained from the calibration of two samples of extremely low frequency magnetic field meters. The paper focuses on the formulation of a suitable model that accounts for the various aspects of the calibration protocol and the subsequent interpretation of the parameter estimates. The approach is very flexible and can easily be tuned to the various needs arising in the measurement agreement framework. It can be seen as an extension of the common practice of using a one-way random-effects model to retrieve a measure of agreement

Reliability and agreement of ELF magnetic field dosimeters: An analysis based on calibration data

In this paper we describe an analysis of reliability and agreement of two types of 50-Hz magnetic \ufb01eld dosimeters, the same instruments which are currently in use in a nation-wide case-control study conducted in Italy to ascertain etiologic factors for childhood cancer. Our analysis is restricted to the calibration setting: we estimated instrument agreement and reliability by utilizing repeated calibration data obtained for the two types of instrument over several values of the reference magnetic \ufb01eld generated in the calibration experiment. The statistical analysis is based on a hierarchical model and is discussed in detail in a previous paper. Here, we summarize our modeling approach and we use a larger set of calibration data to con\ufb01rm our previous \ufb01ndings. We con\ufb01rm a substantial agreement between the two meter types and a lack of bias of any practical meaning. We also con\ufb01rm our \ufb01nding for one of the two meters of a rather strong dependence of the instrument\u2019s measurement error on orientation within the reference magnetic \ufb01eld. It is unclear what the implications of our results may be for epidemiologic studies, particularly in the presence of other sources of error or distortion that may be far more evident in those studies

A hierarchical modeling approach for measuring reliability and agreement of two types of magnetic field meters

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Risk of neuroblastoma, maternal characteristics and perinatal exposures: The SETIL study

Purpose: Neuroblastoma (NB) is the most common extra-cranial paediatric solid tumour. Incidence peaks in infancy, suggesting a role of in-utero and neonatal exposures but its aetiology is largely unknown. The aim of the present study is to evaluate the association between maternal characteristics and perinatal factors with the risk of NB, using data from the SETIL database. Methods: SETIL is a large Italian population-based case-control study established to evaluate several potential cancer risk factors in 0-10 year olds. Information about maternal characteristics, reproductive history, environmental and occupational exposures during pregnancy, as well as newborns' characteristics were obtained using a structured questionnaire. Extremely low frequency magnetic field (ELF-MF) home exposure was measured. The study included 1044 healthy controls and 153 NB cases, diagnosed between 1998 and 2001. Results: A twofold risk was associated to exposure in pregnancy to chemical products for domestic work and to hair dye. The risk associated with the latter was higher among 0-17 month old children (OR. =. 5.5, 95%CI: 1.0-29.3). Risk was increased for children whose mothers had suffered work related exposure in the preconception period to solvents (OR. =. 2.0 95%CI: 1.0-4.1) and in particular to aromatic hydrocarbons (OR. =. 9.2, 95%CI: 2.4-34.3). No association was observed with ELF-MF exposure. A higher risk was found among children with congenital malformations (OR. =. 4.9, 95%CI: 1.8-13.6) or neurofibromatosis (2 cases and 0 controls, p=. 0.016). Conclusions: Our study suggests maternal exposure to hair dyes and aromatic hydrocarbons plays a role and deserves further investigation. The association with congenital malformations might also be explained by over-diagnosis.External exposure, in particular during and before pregnancy might contribute to NB occurrence

Risk of neuroblastoma, maternal characteristics and perinatal exposures: The SETIL study.

Neuroblastoma (NB) is the most common extra-cranial paediatric solid tumour. Incidence peaks in infancy, suggesting a role of in-utero and neonatal exposures but its aetiology is largely unknown. The aim of the present study is to evaluate the association between maternal characteristics and perinatal factors with the risk of NB, using data from the SETIL database.SETIL is a large Italian population-based case-control study established to evaluate several potential cancer risk factors in 0-10 year olds. Information about maternal characteristics, reproductive history, environmental and occupational exposures during pregnancy, as well as newborns' characteristics were obtained using a structured questionnaire. Extremely low frequency magnetic field (ELF-MF) home exposure was measured. The study included 1044 healthy controls and 153 NB cases, diagnosed between 1998 and 2001.A twofold risk was associated to exposure in pregnancy to chemical products for domestic work and to hair dye. The risk associated with the latter was higher among 0-17 month old children (OR=5.5, 95\%CI: 1.0-29.3). Risk was increased for children whose mothers had suffered work related exposure in the preconception period to solvents (OR=2.0 95\%CI: 1.0-4.1) and in particular to aromatic hydrocarbons (OR=9.2, 95\%CI: 2.4-34.3). No association was observed with ELF-MF exposure. A higher risk was found among children with congenital malformations (OR=4.9, 95\%CI: 1.8-13.6) or neurofibromatosis (2 cases and 0 controls, p=0.016).Our study suggests maternal exposure to hair dyes and aromatic hydrocarbons plays a role and deserves further investigation. The association with congenital malformations might also be explained by over-diagnosis. External exposure, in particular during and before pregnancy might contribute to NB occurrence