S J Hepworth

Publications of S J Hepworth

• Deoxynivalenol exposure assessment in a cohort of pregnant women from Bradford, UK.

  Authors: S J Hepworth, L J Hardie, L K Fraser, V J Burley, R S Mijal, C P Wild, R Azad, P A McKinney, P C Turner

  Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment. 01/2011; 29(2):269-76.

  Deoxynivalenol (DON) is a ubiquitous contaminant of cereal crops in temperate regions of the world. It causes growth faltering and immune suppression in animals. Limited information is available onDeoxynivalenol (DON) is a ubiquitous contaminant of cereal crops in temperate regions of the world. It causes growth faltering and immune suppression in animals. Limited information is available on DON exposure in UK subpopulations. The objective of this study was to provide DON exposure assessment in a subset of pregnant women scheduled for an elective caesarean in a large multi-ethnic mother/infant birth cohort from Bradford, UK. Women aged 16-44 years (n = 85) provided a urine sample for DON analysis in the last trimester of pregnancy, and concurrently completed a food-frequency questionnaire (FFQ). The urinary DON biomarker was detected in all measured samples (geometric mean (GM) = 10.3 ng DON mg(-1) creatinine, range = 0.5-116.7 ng mg(-1)). Levels were higher in women classified as South Asian in origin (GM: 15.2 ng mg(-1); 95% CI = 10.7-21.5 ng mg(-1)) compared with non-South Asians (GM = 8.6 ng mg(-1); 95% CI = 6.6-11.8 ng mg(-1)), p = 0.02). Estimated DON intake from FFQ data and typical levels of DON contamination of food suggest that this was mainly due to higher levels of exposure from bread, particularly daily intake of DON from chapattis in South Asians (estimated mean = 2.4 µg day(-1); 95% CI = 1.2, 3.7 µg day(-1)) compared with non-South Asians (estimated mean = 0.2 µg day(-1); 95% CI = 0-0.4 µg day(-1)), p < 0.001. This is the first biomarker demonstration of DON exposure in pregnant women, and several urinary DON levels were the highest ever recorded in any study. A larger survey within this birth cohort is warranted to investigate any potential risk to mothers and their babies, from DON exposure during pregnancy.

• Dietary acrylamide intake and risk of breast cancer in the UK women's cohort.

  Authors: V J Burley, D C Greenwood, S J Hepworth, L K Fraser, T M de Kok, S G van Breda, S A Kyrtopoulos, M Botsivali, J Kleinjans, P A McKinney, J E Cade

  British journal of cancer. 10/2010; 103(11):1749-54.

  No studies to date have demonstrated a clear association with breast cancer risk and dietary exposure to acrylamide.Methods:A 217-item food frequency questionnaire was used to estimate dietaryNo studies to date have demonstrated a clear association with breast cancer risk and dietary exposure to acrylamide.Methods:A 217-item food frequency questionnaire was used to estimate dietary acrylamide intake in 33,731 women aged 35-69 years from the UK Women's Cohort Study followed up for a median of 11 years. In all, 1084 incident breast cancers occurred during follow-up. There was no evidence of an overall association between acrylamide intake and breast cancer (hazard ratio=1.08 per 10 μg day(-1), 95% CI: 0.98-1.18, P(trend)=0.1). There was a suggestion of a possible weak positive association between dietary acrylamide intake and premenopausal breast cancer after adjustment for potential confounders (hazard ratio=1.2, 95% CI: 1.0-1.3, P(trend)=0.008). There was no suggestion of any association for postmenopausal breast cancer (hazard ratio=1.0, 95% CI: 0.9-1.1, P(trend)=0.99). There is no evidence of an association between dietary acrylamide intake and breast cancer. A weak association may exist with premenopausal breast cancer, but requires further investigation.

• Determinants of mobile phone output power in a multinational study - implications for exposure assessment.

  Authors: M Vrijheid, S Mann, P Vecchia, J Wiart, M Taki, L Ardoino, B K Armstrong, A Auvinen, D Bédard, G Berg-Beckhoff [......] S Lagorio, S Lönn, M McBride, L Montestruq, Rc Parslow, S Sadietzki, J Schüz, T Tynes, A Woodward, E Cardis

  Occupational and environmental medicine. 06/2009;

  OBJECTIVES: The output power of a mobile phone is directly related to its radiofrequency (RF) electromagnetic field strength, and may theoretically vary substantially in different networks and phoneOBJECTIVES: The output power of a mobile phone is directly related to its radiofrequency (RF) electromagnetic field strength, and may theoretically vary substantially in different networks and phone use circumstances due to power control technologies. To improve indices of RF exposure for epidemiological studies, we assessed determinants of mobile phone output power in a multi-national study. METHODS: More than 500 volunteers in twelve countries used software-modified GSM phones (SMPs) for approximately one month each. The SMPs recorded date, time, and duration of each call, and the frequency band and output power at fixed sampling intervals throughout each call. Questionnaires provided information on the typical circumstances of an individual's phone use. Linear regression models were used to analyse the influence of possible explanatory variables on the average output power and the percentage call-time at maximum power for each call. RESULTS: Measurements of over 60,000 phone calls showed that the average output power was approximately 50% of the maximum, and that output power varied by a factor of up to 2 to 3 between study centres and network operators. Maximum power was used during a considerable proportion of call-time (39% on average). Output power decreased with increasing call duration, but showed little variation in relation to reported frequency of use whilst in a moving vehicle or inside buildings. Higher output powers for rural compared with urban use of the SMP were observed principally in Sweden where the study covered very sparsely populated areas. CONCLUSIONS: Average power levels are substantially higher than the minimum levels theoretically achievable in GSM networks. Exposure indices could be improved by accounting for average power levels of different telecommunications systems. There appears to be little value in gathering information on circumstances of phone use other than use in very sparsely populated regions.

• Dietary zinc intake and brain cancer in adults: a case-control study.

  Authors: P Dimitropoulou, S Nayee, J F Liu, L Demetriou, M van Tongeren, S J Hepworth, K R Muir

  The British journal of nutrition. 04/2008; 99(3):667-73.

  Little is known about the aetiology of brain tumours. One putative factor suggested from animal models is a protective effect of dietary Zn. We tested the hypothesis that increased compared with lowLittle is known about the aetiology of brain tumours. One putative factor suggested from animal models is a protective effect of dietary Zn. We tested the hypothesis that increased compared with low dietary Zn intake is protective against brain tumour development. We conducted a population-based case-control study in the UK, of adults aged 18-69 years, between 2001 and 2004 aiming to identify possible risk factors. Dietary information was collected from 637 cases diagnosed with a glioma or meningioma, and 876 controls. Data were obtained from a self-completed FFQ. Multivariate logistic regression analysis was conducted, adjusting for socio-demographic factors, season of questionnaire return, multivitamin supplementation and energy intake. Although a weak protective effect was observed for the third quartile of intake (normal compared with low intake) in the meningioma group, this was limited to the specific brain tumour subtype and quartile, and was not significant after also adjusting for intake of other elements. Overall there was no significant effect of Zn intake. No association or dose-response relationship was observed between increased compared with low Zn intake and risk of glioma or meningioma.

• Atopic dysfunction and risk of central nervous system tumours in children.

  Authors: N J Harding, J M Birch, S J Hepworth, P A McKinney

  European journal of cancer (Oxford, England : 1990). 02/2008; 44(1):92-9.

  Risk factors for central nervous system (CNS) tumours in children remain largely unknown. Evidence of an inverse relationship between atopy and tumour development exists in adults but little is knownRisk factors for central nervous system (CNS) tumours in children remain largely unknown. Evidence of an inverse relationship between atopy and tumour development exists in adults but little is known about childhood tumours. This study aims to examine the risk of childhood CNS tumours given a history of eczema and asthma. Cases of children diagnosed with CNS tumours (n=575) and controls (n=6292) from the UK Childhood Cancer Study (UKCCS) were analysed using conditional logistic regression comparing reported histories of allergic disease. Asthma was statistically significantly and negatively associated with all CNS tumours (odds ratios, OR 0.75, confidence of interval, CI(95%): 0.58-0.97), though this was not observed for eczema (OR 0.94, CI(95%): 0.74-1.18). Individuals who had suffered both asthma and eczema showed the most significant reduction in risk (OR 0.48, CI(95%): 0.28-0.81). Analysis by tumour subtype showed the strongest effect for the medulloblastoma/PNET group. These results may have a biological explanation with raised immunosurveillance in atopic individuals protecting against the development of brain tumours. Alternative explanations might include bias, reverse causality or confounding.

• Breastfeeding and risk of childhood CNS tumours.

  Authors: N J Harding, J M Birch, S J Hepworth, P A McKinney

  British journal of cancer. 04/2007; 96(5):815-7.

  We investigated infant feeding habits in relation to risk of childhood central nervous system tumours among 633 cases in the UK Childhood Cancer Study (UKCCS). No significant effect of breastfeedingWe investigated infant feeding habits in relation to risk of childhood central nervous system tumours among 633 cases in the UK Childhood Cancer Study (UKCCS). No significant effect of breastfeeding was detected overall (odds ratio 1.01, confidence interval: 0.85-1.21) nor in any morphological subgroup. Similarly, no effect for the duration of breastfeeding or any other feeding practices was observed.

• History of allergic disease and risk of meningioma.

  Authors: M J Schoemaker, A J Swerdlow, S J Hepworth, M van Tongeren, K R Muir, P A McKinney

  American journal of epidemiology. 03/2007; 165(5):477-85.

  Epidemiologic studies have consistently shown inverse associations of allergic disease with risk of glioma, but it is unclear whether this association also applies to meningioma. The authorsEpidemiologic studies have consistently shown inverse associations of allergic disease with risk of glioma, but it is unclear whether this association also applies to meningioma. The authors conducted a pooled analysis of meningioma risk in relation to a history of allergic disease based on data from two population-based, case-control studies with 475 cases and 1,716 controls in the United Kingdom (2001-2004). Meningioma risk was significantly reduced in relation to self-reported, physician-diagnosed allergic disease (odds ratio = 0.76, 95% confidence interval (CI): 0.61, 0.96) but was nonsignificantly reduced for individual conditions: asthma (odds ratio = 0.85, 95% CI: 0.61, 1.18), hay fever (odds ratio = 0.81, 95% CI: 0.62, 1.06), and eczema (odds ratio = 0.72, 95% CI: 0.51, 1.02). Risk reductions were greatest for asthma (odds ratio = 0.43, 95% CI: 0.21, 0.89) and hay fever (odds ratio = 0.50, 95% CI: 0.25, 1.00) with an early age at onset (<10 years) and for eczema (odds ratio = 0.46, 95% CI: 0.21, 1.07) with an onset at ages 10-19 years; they were near unity for onset in adulthood. This study suggests an inverse association between a history of allergies and meningioma risk, but with smaller risk reductions than for glioma. The reasons for this association need clarification, as well as an etiologic explanation. Consideration also needs to be given to confounding or bias.

• Validation of short term recall of mobile phone use for the Interphone study.

  Authors: M Vrijheid, E Cardis, B K Armstrong, A Auvinen, G Berg, K G Blaasaas, J Brown, M Carroll, A Chetrit, H C Christensen [......] S Lönn, P A McKinney, L Montestrucq, R C Parslow, L Richardson, S Sadetzki, T Salminen, J Schüz, T Tynes, A Woodward

  Occupational and environmental medicine. 05/2006; 63(4):237-43.

  AIM: To validate short term recall of mobile phone use within Interphone, an international collaborative case control study of tumours of the brain, acoustic nerve, and salivary glands related toAIM: To validate short term recall of mobile phone use within Interphone, an international collaborative case control study of tumours of the brain, acoustic nerve, and salivary glands related to mobile telephone use. METHODS: Mobile phone use of 672 volunteers in 11 countries was recorded by operators or through the use of software modified phones, and compared to use recalled six months later using the Interphone study questionnaire. Agreement between recalled and actual phone use was analysed using both categorical and continuous measures of number and duration of phone calls. RESULTS: Correlations between recalled and actual phone use were moderate to high (ranging from 0.5 to 0.8 across countries) and of the same order for number and duration of calls. The kappa statistic demonstrated fair to moderate agreement for both number and duration of calls (weighted kappa ranging from 0.20 to 0.60 across countries). On average, subjects underestimated the number of calls per month (geometric mean ratio of recalled to actual = 0.92, 95% CI 0.85 to 0.99), whereas duration of calls was overestimated (geometric mean ratio = 1.42, 95% CI 1.29 to 1.56). The ratio of recalled to actual use increased with level of use, showing underestimation in light users and overestimation in heavy users. There was substantial heterogeneity in this ratio between countries. Inter-individual variation was also large, and increased with level of use. CONCLUSIONS: Volunteer subjects recalled their recent phone use with moderate systematic error and substantial random error. This large random error can be expected to reduce the power of the Interphone study to detect an increase in risk of brain, acoustic nerve, and parotid gland tumours with increasing mobile phone use, if one exists.

• Assigning exposure to pesticides and solvents from self-reports collected by a computer assisted personal interview and expert assessment of job codes: the UK Adult Brain Tumour Study.

  Authors: S J Hepworth, A Bolton, R C Parslow, M van Tongeren, K R Muir, P A McKinney

  Occupational and environmental medicine. 05/2006; 63(4):267-72.

  OBJECTIVES: To compare assignment of occupational pesticide and solvent exposure using self-reported data collected by a computer assisted personal interview (CAPI) with exposure based on expertOBJECTIVES: To compare assignment of occupational pesticide and solvent exposure using self-reported data collected by a computer assisted personal interview (CAPI) with exposure based on expert assessment of job codes. To discuss the advantages and disadvantages of using a CAPI to collect individual occupational exposure data. METHODS: Between 2001 and 2004, 1495 participants were interviewed using a CAPI for a case-control study of adult brain tumours and acoustic neuromas. Two types of occupational data were collected: (1) a full history, including job title from which a job code was assigned from the Standard Occupational Classification; and (2) specific details on pesticide and solvent exposure reported by participants. Study members' experiences of using the CAPI were recorded and advantages and disadvantages summarised. RESULTS: Of 7192 jobs recorded, the prevalence of self-reported exposure was 1.3% for pesticides and 11.5% for solvents. Comparing this with exposure expertly assessed from job titles showed 53.6% and 45.8% concordance for pesticides and solvents respectively. Advantages of the CAPI include no data entry stage, automatic input validation, and a reduction in interviewer bias. Disadvantages include an adverse effect on study implementation as a consequence of resources required for programming and difficulties encountered with data management prior to analysis. CONCLUSIONS: Different methods of exposure assessment derive different exposure levels for pesticide and solvent exposure at work. Agreement between self-reported and expert assessment of exposure was greater for pesticides compared to solvents. The advantages of using a CAPI for the collection of complex data outweigh the disadvantages for interviewers and data quality but using such a method requires extra resources at the study outset.

• Mobile phone use and risk of acoustic neuroma: results of the Interphone case-control study in five North European countries.

  Authors: M J Schoemaker, A J Swerdlow, A Ahlbom, A Auvinen, K G Blaasaas, E Cardis, H Collatz Christensen, M Feychting, S J Hepworth, C Johansen, L Klaeboe, S Lönn, P A McKinney, K Muir, J Raitanen, T Salminen, J Thomsen, T Tynes

  British journal of cancer. 11/2005; 93(7):842-8.

  There is public concern that use of mobile phones could increase the risk of brain tumours. If such an effect exists, acoustic neuroma would be of particular concern because of the proximity of theThere is public concern that use of mobile phones could increase the risk of brain tumours. If such an effect exists, acoustic neuroma would be of particular concern because of the proximity of the acoustic nerve to the handset. We conducted, to a shared protocol, six population-based case-control studies in four Nordic countries and the UK to assess the risk of acoustic neuroma in relation to mobile phone use. Data were collected by personal interview from 678 cases of acoustic neuroma and 3553 controls. The risk of acoustic neuroma in relation to regular mobile phone use in the pooled data set was not raised (odds ratio (OR) = 0.9, 95% confidence interval (CI): 0.7-1.1). There was no association of risk with duration of use, lifetime cumulative hours of use or number of calls, for phone use overall or for analogue or digital phones separately. Risk of a tumour on the same side of the head as reported phone use was raised for use for 10 years or longer (OR = 1.8, 95% CI: 1.1-3.1). The study suggests that there is no substantial risk of acoustic neuroma in the first decade after starting mobile phone use. However, an increase in risk after longer term use or after a longer lag period could not be ruled out.

• Recall of past use of mobile phone handsets.

  Authors: R C Parslow, S J Hepworth, P A McKinney

  Radiation protection dosimetry. 02/2003; 106(3):233-40.

  Previous studies investigating health effects of mobile phones have based their estimation of exposure on self-reported levels of phone use. This UK validation study assesses the accuracy of reportedPrevious studies investigating health effects of mobile phones have based their estimation of exposure on self-reported levels of phone use. This UK validation study assesses the accuracy of reported voice calls made from mobile handsets. Data collected by postal questionnaire from 93 volunteers was compared to records obtained prospectively over 6 months from four network operators. Agreement was measured for outgoing calls using the kappa statistic, log-linear modelling, Spearman correlation coefficient and graphical methods. Agreement for number of calls gained moderate classification (kappa = 0.39) with better agreement for duration (kappa = 0.50). Log-linear modelling produced similar results. The Spearman correlation coefficient was 0.48 for number of calls and 0.60 for duration. Graphical agreement methods demonstrated patterns of over-reporting call numbers (by a factor of 1.7) and duration (by a factor of 2.8). These results suggest that self-reported mobile phone use may not fully represent patterns of actual use. This has implications for calculating exposures from questionnaire data.