Assessment of foetal exposure to the homogeneous magnetic field harmonic spectrum generated by electricity transmission and distribution networks

During the last decades studies addressing the effects of exposure to Extremely Low Frequency Electromagnetic Fields (ELF-EMF) have pointed out a possible link between those fields emitted by power lines and childhood leukaemia. They have also stressed the importance of also including in the assessment the contribution of frequency components, namely harmonics, other than the fundamental one. Based on the spectrum of supply voltage networks allowed by the European standard for electricity quality assessment, in this study the exposure of high-resolution three-dimensional models of foetuses to the whole harmonic content of a uniform magnetic field with a fundamental frequency of 50 Hz, was assessed. The results show that the main contribution in terms of induced electric fields to the foetal exposure is given by the fundamental frequency component. The harmonic components add some contributions to the overall level of electric fields, however, due to the extremely low permitted amplitude of the harmonic components with respect to the fundamental, their amplitudes are low. The level of the induced electric field is also much lower than the limits suggested by the guidelines for general public exposure, when the amplitude of the incident magnetic field is set at the maximum permitted level

Risk Factors for Endometrioid, Mucinous and Serous Benign Ovarian Cysts

Parazzini F (Mario Negri Institute for Pharmacological Research, Via Eritrea 62, 20157 Milan, Italy), La Vecchia C, Franceschi S, Negri E and Cecchettil G. Risk factors for endometrioid, mucinous and serous benign ovarian cysts. International Journal of Epidemiology 1989, 18: 108-112. To evaluate the risk factors for serous, mucinous and endometrioid ovarian cysts, data were collected in a case-control study conducted in the greater Milan area based on 202 women with benign cysts (114 endometrioid and 88 serous or mucinous) of the ovary and 1127 controls. Questions were asked about menstrual and reproductive characteristics, marital status, education, history of various diseases, and lifetime use of oral contraceptives and other hormonal treatments. Higher social class, earlier menarche and longer interval between age at first marriage and first birth, a likely indicator of subfertility, were associated with an increased risk of serous, mucinous and endometrioid cysts. Women with endometrioid cyst were characterized by low parity, less frequent irregular or long menses, more frequent oral contraceptive use and low body mass index, while the most relevant risk factor associated with serous and mucinous cysts was greater age at first birth. The present data point out the epidemiological differences between endometrioid and serous or mucinous cysts. Further, they suggest that analyses of risk factors for epithelial ovarian cancer subdivided by various histotypes may be of interest in order to confirm possible heterogeneities in the aetiology of ovarian epithelial neoplasm

Relative and Attributable Risk for Cervical Cancer: A Comparative Study in the United States and Italy

Parazzini F {Istituto di Ricerche Farmacologiche ‘Mario Negri' via Eritrea 62,20157 Milan, Italy), Hildesheim A, Ferraroni M, La Vecchia C and Brinton LA. Relative and attributable risk for cervical cancer: A comparative study in Italy and the United States. International Journal of Epidemiology 1990, 19: 539-545. The attributable risk for invasive cervical cancer in the US and Italian populations has been estimated in relation to main ‘aetiological' factors (number of sexual partners, age at first intercourse, parity, oral contraceptive use and smoking) and history of Pap smear using data from two case-control studies conducted in the US (466 cases and 788 controls) and Italy (528 cases and 456 controls). The risk of cervical cancer increased in both studies with multiple sexual partners, decreasing age at first intercourse, higher parity, oral contraceptive use and smoking. Levels of exposure to various risk factors were markedly different in the two countries (ie number of sexual partners, frequency of oral contraceptive use and smoking were greater in the US). Multiple Pap smears and a short interval since last Pap smear strongly reduced risk of cervical cancer in both populations, although screening was much more widespread in the US study population, with only 9% of controls reporting no previous smear versus 38% of the Italian control series. The combined population attributable risk for the five ‘aetiological' risk factors was slightly greater in the US study (76%) than in the Italian one (69%), chiefly because of a higher prevalence of exposure to sexual factors in US study women. A substantially larger proportion of Italian cases were due in part to deficiency in screening (46% in US and 84% in Italy). Thus, further inclusion of the effect of screening programmes (number of Pap smears and time since last Pap) led to an overall proportion of cases attributable to the examined risk factors of 87% in the US and 95% in Ital

Risk Factors for Spontaneous Abortion

A case-control study was conducted to evaluate risk factors for spontaneous abortions. Cases were 94 women with two or more unexplained miscarriages (after exclusion of genetic, endocrine and Müllerian factors) and no term pregnancy, controls were 176 women admitted for normal delivery to the same clinic where cases were identified. Questions were asked about personal characteristics and habits, and gynaecological history. A family history of recurrent miscarriage was more common among women with spontaneous miscarriages than among the controls (13 cases versus 8 controls, relative risk (RR) =3.2, 95% confidence interval (CI) = 1.3-8.1). Compared to women whose menarche occurred at age 11 or younger, the RRs were 0.8 when menarche occurred at age 12-13 and 0.5 at age 14 or more: this trend in risk was statistically significant. Compared with never smokers, current smokers had about a 40% increased risk of miscarriage and the risk increased with number of cigarettes per day. No association emerged with socio-demographic characteristics (e.g. education, marital status, age of the partner), reproductive history (age at first pregnancy), type of contraceptive used and other general lifestyle habits (e.g. alcohol or coffee consumption

Oral Contraceptive Use and Invasive Cervical Cancer

Parazzini F (Mario Negri Institute for Pharmacological Research, 20157 Milan, Italy), La Vecchia C, Negri E and Maggi R. Oral contraceptive use and invasive cervical cancer. International Journal of Epidemiology 1990; 19: 259-263. The relationship between oral contraceptive use and the risk of invasive cervical cancer was investigated using data from a hospital-based case-control study conducted in the greater Milan area, Northern Italy. A total of 367 women under 60 years of age with a histologically confirmed diagnosis of invasive cervical cancer was compared with a group of 323 controls admitted for a spectrum of acute conditions, non-gynaecological, hormonal or neoplastic and apparently unrelated to oral contraceptive use. Cases had used oral contraceptives more frequently than controls, the age-adjusted relative risk (RR) being 1.53 (95% confidence interval 0.99-2.36). The risk increased with duration of use: compared with never users the age-adjusted RR was 1.48 for up to two years and 1.83 for more than two years (x12 = 5.28, p = 0.02). Allowing for major identified potential confounding factors, including sexual and reproductive habits, by means of multiple logistic regression, did not explain the associaton (multivariate RR 1.85 for ever use, 1.05 for up to two years and 2.47 for more than two years). When the interaction between oral contraceptive use and parity or sexual habits was analysed, the effects of various factors appeared independent: the point estimate for multiparous oral contraceptive users versus nulliparous never users was 8.01. There was no consistent influence on risk of invasive cervical cancer of age at first use, whereas the RRs were slightly greater for women who had first used oral contraceptives less than ten years before or had last used them less than five years before diagnosis: these findings, however, were far from significan

Risk Factors for Epithelial Ovarian Tumours of Borderline Malignancy

A case-control study was conducted on 91 cases with histologically-confirmed borderline ovarian turnours and 237 control subjects in hospital for acute non-gynaecological, hormonal or neoplastic disease. Women reporting three or more births, compared to nulliparae, had a relative risk (RR) estimate of 0.6, but this finding was not statistically significant (95% confidence interval (CI): 0.2-1.4). The risk of borderline turnours increased, although not significantly, with later age at first birth: compared to women reporting first birth at age 24 or before, the RRs were 1.3 and 1.7 in those reporting respectively their first birth at age 25-29 and 30 years or more. No significant relationship emerged between borderline ovarian cancer and age at menarche, menopausal status and lifelong menstrual pattern. Cases tended to report a later age at menopause than controls, but the trend in risk was not statistically significant. Nine cases (9.9%) and 68 controls (24.9%) reported oral contraceptive use: compared with never users the multivariate RR for ever users was 0.3, and the risk dropped with duration of use to 0.2 in users for two years or more (X21, trend = 12.70, p<0.001). This study provides epidemiological evidence of a pathogenetic continuum between borderline and invasive ovarian tumour

Family History of Breast, Ovarian and Endometrial Cancer and Risk of Breast Cancer

The relationship between family history of breast, ovarian and endometrial cancer and risk of breast cancer was analysed using data from a case-control study of breast cancer conducted in the greater Milan area, Northern Italy. The cases studied were 3415 women (median age 52 years, range 23-74) who had histdogically confirmed breast cancer diagnosed within the year precedmg the interview. The controls were 2916 women (median age 54 years; range 21-74] In hospital for a spectrum of acute illnesses excluding gynaecological, hormonal or neoplastic conditions. A total of 375 cases (11.0%) and 128 controls (4.4%) reported a history of breast cancer in first degree relatives. Compared with women with no family history of breast cancer, the RR was 2.7 (95% confidence Interval [CI] : 2.2-3.3) in those with one first degree relative affected and 2.8 (95% CI : 1.3-5.7) in those with two or more affected relatives. In comparison with women without family history of ovarlan cancer the RR of breast cancer was 1.4 (95% CI : 0.9-2.3) for those reporting one or more first degree relatives with ovarian cancer. However, the multivariate estimate for family history of ovarian cancer, including a term for familial breast cancer, decreased to 0.8 (95% CI : 0.5-1.4). The risk of breast cancer was similar in women reporting a family history of breast cancer (RR=2.2) and in those reporting a family history of both breast and ovarian cancer (RR=2.51, in cornparkon with women reporting no family history of breast and/or ovarian cancer. When tlia relation with family history of breast cancer was analysed in strata of women with and without family history of ovarian cancer, no difference was found in the RR estimates: the RR for family history of breast cancer was 2.8 in women with family history of ovarian cancer and 2.7 in those without history of ovarian cancer. No relation was found between history of endometrial cancer in first degree relatives and risk of breast cance