A retrospective cohort mortality study of Italian commercial airline cockpit crew and cabin attendants, 1965-96

A retrospective cohort mortality study was conducted among Italian commercial flight personnel for the period 1965-1996. The cohort was composed of 3,022 male cockpit crew members and 3,418 male and 3,428 female cabin attendants. Cause-specific standardized mortality ratios (SMRs) and exact 95% confidence intervals (CIs) were calculated as estimates of the relative risk. Mortality from all cancers was less than expected for all categories (SMRs of 0.58 for male cockpit crew, 0.67 for male cabin attendants, and 0.90 for female cabin attendants). Among male flight personnel, the SMR for leukemia was somewhat elevated (SMR 1.73; 95% CI: 0.75-3.41) based on eight deaths, with a positive trend by length of employment (p = 0.046). Additionally, an excess of death by suicide was seen among female cabin attendants (SMR 3.38; 95% CI: 1.24-7.35). Other Italian studies of flight personnel are under way, including a detailed assessment of cosmic radiation exposure and investigations of non-radiation occupational risk factors and prevalence of nonfatal outcomes.     

A Retrospective Cohort Mortality Study of Italian Commercial Airline Cockpit Crew and Cabin Attendants, 1965–96

Abstract

A retrospective cohort mortality study was conducted among Italian commercial flight personnel for the period 1965-1996. The cohort was composed of 3,022 male cockpit crew members and 3,418 male and 3,428 female cabin attendants. Cause-specific standardized mortality ratios (SMRs) and exact 95% confidence intervals. (CIs) were calculated as estimates of the relative risk. Mortality from all cancers was less than expected forall categories (SMRs of 0.58 for male cockpit crew, 0.67 for male cabin attendants, and 0.90 for female cabin attendants). Among male flight persopnel, the SMR for leukemia was somewhat elevated (SMR 1.73; 95% CI: 0.75–3.41) based on eight deaths, with a positive trend by length of employment (p = 0.046). Additionally, an excess of death by suicide was seen among female cabin attendants (SMR 3.38; 95% CI: 1.24–7.35). Other Italian studies of flight personnel are under way, including a detailed assessment of cosmic radiation exposure and investigations of non-radiation occupational risk factors and prevalence of nonfatal outcomes.     

Pregnancy outcome among offspring of airline pilots and cabin attendants

OBJECTIVES: This study assessed the occurrence of perinatal death, low birthweight, preterm birth, and birth defects (total, major, neural tube defects, total cleft, cleft palate, hypospadias, and Down syndrome) in the offspring of airline pilots and cabin attendants. METHODS: A cohort of offspring of airline pilots and cabin attendants was established and characterized in terms of parental exposure to cosmic radiation the year before birth or ever. Pregnancy outcome was derived from the Medical Birth Register of Norway. The reference group comprised offspring of parents without occupational exposure to cosmic radiation. RESULTS: No deviant risks were observed for the offspring of male pilots, either for the year preceding birth (N=2,111) or ever (N=2,356). Specific birth outcomes were fewer for the pilots than for the referents (N=1,621,186), except for Down syndrome, which was more frequent [odds ratio (OR) 1.41, 95% confidence interval (95% CI) 0.53-3.76]. For exposure the year preceding birth (N=2,512), the risk of low birthweight was lower for the female cabin attendants than for the referents (adjusted OR 0.83, 95% CI 0.69-1.00), while Down syndrome was more frequent (OR 1.44, 95% CI 0.60-3.47). For exposure ever (N=3346), the risk of low birthweight was lower (OR 0.82, 95% CI 0.70-0.96) for the cabin attendants, while hypospadias (OR 1.18, 95% CI 0.61-3.04) and Down syndrome (OR 1.79, 95% CI 0.03-3.45) were more frequent CONCLUSIONS: In general, offspring of air pilots and cabin attendants do not seem to be at increased risk of adverse pregnancy outcome.     

Mortality from cancer and other causes among airline cabin attendants in Europe: a collaborative cohort study in eight countries

There is concern about the health effects of exposure to cosmic radiation during air travel. To study the potential health effects of this and occupational exposures, the authors investigated mortality patterns among more than 44,000 airline cabin crew members in Europe. A cohort study was performed in eight European countries, yielding approximately 655,000 person-years of follow-up. Observed numbers of deaths were compared with expected numbers based on national mortality rates. Among female cabin crew, overall mortality (standardized mortality ratio (SMR) = 0.80, 95% confidence interval (CI): 0.73, 0.88) and all-cancer mortality (SMR = 0.78, 95% CI: 0.66, 0.95) were slightly reduced, while breast cancer mortality was slightly but nonsignificantly increased (SMR = 1.11, 95% CI: 0.82, 1.48). In contrast, overall mortality (SMR = 1.09, 95% CI: 1.00, 1.18) and mortality from skin cancer (for malignant melanoma, SMR = 1.93, 95% CI: 0.70, 4.44) among male cabin crew were somewhat increased. The authors noted excess mortality from aircraft accidents and from acquired immunodeficiency syndrome in males. Among airline cabin crew in Europe, there was no increase in mortality that could be attributed to cosmic radiation or other occupational exposures to any substantial extent. The risk of skin cancer among male crew members requires further attention.     

Risk of spontaneous abortion among women exposed to polybrominated biphenyls

Accidental contamination of livestock in Michigan in 1973 with polybrominated biphenyls (PBBs) led to the establishment of a registry of exposed individuals in 1976. At the time of enrollment, serum was collected and analyzed for PBBs and polychlorinated biphenyls (PCBs). In 1997, women aged 18 years or older and active in the registry were invited to participate in a telephone interview about their health. Using generalized estimating equations to account for correlated outcomes within the same woman, we assessed the risk of spontaneous abortion among 529 women with 1344 potentially exposed pregnancies. PBB and PCB exposure were not associated with risk of spontaneous abortion after adjusting for maternal age at conception, age at menarche, and prior infertility. Compared to pregnancies with PBB exposure below the limit of detection, those with levels above 2.9 ppb had a non-significant reduced odds of spontaneous abortion (adjusted OR=0.73; 95% CI=0.47-1.13). Compared to pregnancies with PCB exposure below the limit of detection, those with levels above 6.5 ppb had little difference in risk (adjusted OR=0.91; 95% CI=0.59-1.41). Maternal age at conception above 34 years was significantly associated with elevated risk of spontaneous abortion (OR=2.46; 95% CI=1.10-5.49). The effect of prior infertility was of borderline significance (OR=1.52; 95% CI=0.98-2.38). Older age at menarche was associated with decreased risk of spontaneous abortion (adjusted OR=0.58; 95% CI: 0.38-0.89, comparing menarche at 12-13 with menarche <12). Our results do not support an association between exposure to PBBs or PCBs and risk of spontaneous abortion.     

Pregnancy outcomes in females after treatment for childhood cancer

This Ontario province-wide cohort study was conducted to compare the risk of adverse pregnancy outcomes in female childhood cancer survivors who received abdominal-pelvic radiation and/or chemotherapy with alkylating agents with the risk among those who were treated by non-sterilizing alkylating agents with the risk among those who were treated by non-sterilizing surgery only. Females in Ontario, Canada, diagnosed in 1964-1988 before age 20 with a histologically confirmed malignancy and who had survived for at least 5 years, attained age 18, and were alive at the time of study, were identified through the Ontario Cancer Registry. We ascertained pregnancy outcomes by a telephone-administered questionnaire. Treatment data were abstracted from medical records for 830 subjects 18-49 years of age, the analysis comprised 340 survivors who had one or more pregnancies after treatment. There was no evidence of an increased risk of having a spontaneous abortion or an infant with a birth defect. Survivors receiving abdominal-pelvic radiation were more likely to have a low birth weight infant (odds ratio estimate [OR] = 3.64; 95% confidence interval [CI] = 1.33-9.96), a premature low birth weight infant (OR = 3.29; 95% CI = 0.97-11.1), or an infant who died in the perinatal period (OR = 2.41; 95% CI = 0.50-11.5), compared with those receiving surgery. Risks of perinatal death and having a low birth weight infant increased with dose of radiotherapy directed to the abdomen.     

Mortality among pilots and cabin crew in Greece, 1960-1997

BACKGROUND: Specific health hazards, among them radiation of cosmic origin, have caused some concern among aircrew in civil aviation in recent years. Several cohort studies in Northern countries have investigated mortality and cancer incidence among aircrew. Our goal was to study the pattern of mortality among Greek commercial airline cockpit and cabin crew. METHODS: We performed a retrospective cohort study including 843 Olympic Airways cockpit crew and 1835 cabin attendants. Standardized mortality ratios (SMR) were calculated based on death rates of the Greek population. Duration of employment as a proxy for occupational exposure was used to stratify the cohort. RESULTS: For cockpit crew, the overall SMR was 0.7 (n = 65, 95% CI: 0.5-0.9). The SMR for all cancers was also significantly decreased (n = 17; SMR = 0.6; 95% CI: 0.3-0.9). Most of this reduction was due to a large deficit in lung cancer deaths (SMR = 0.1; 95% CI: 0.0-0.5). Slight but non-significant increases were noted for brain and liver cancer. The SMR for cardiovascular death was close to unity. Among female cabin attendants the SMR for all causes was 0.8 (95% CI: 0.4-1.3). The SMR for all cancers was 0.8 (95% CI: 0.3-1.7). Mortality from breast cancer was not increased. Among male cabin crew, SMR for all causes was 0.5 (95% CI: 0.3-0.9). Analyses according to duration of employment showed no pattern. CONCLUSIONS: In this first-ever occupational cohort study in Greece, Greek aircrew had a low overall and cancer mortality. Due to the small number of events, the strength of our study is limited. The Greek data will be included in a pooled analysis of European studies.     

Prior spontaneous abortion, prior elective termination, interpregnancy interval, and risk of neural tube defects

A woman with a history of spontaneous abortion in her immediately prior pregnancy may be at increased risk for a pregnancy affected by a neural tube defect (NTD). A short interpregnancy interval may further increase this risk. Using data from a population-based case-control study (1989-1991), the authors investigated NTD risk resulting from a prior spontaneous abortion or elective termination and a short interpregnancy interval. Of 538 interviewed case mothers and 539 interviewed control mothers, 408 case mothers and 433 control mothers reported having a prior pregnancy. Analysis showed a slightly decreased NTD risk among mothers whose immediately prior pregnancy had ended in a spontaneous abortion or elective termination in comparison with a live birth (odds ratio (OR) = 0.82; 95% confidence interval (CI): 0.61, 1.1). This decreased risk was consistent across strata of short or long interpregnancy intervals. Additional analysis revealed an increased NTD risk for mothers with an interpregnancy interval of < or =6 months compared with >12-< or =24 months (OR = 1.5; 95% CI: 0.93, 2.4). This latter risk was greatest among mothers whose immediately prior pregnancy had resulted in a live birth (OR = 2.0; 95% CI: 1.0, 3.8) rather than a spontaneous abortion or elective termination (OR = 0.96; 95% CI: 0.44, 2.1). Adjustment for potential covariates did not substantially alter observed risk estimates.     

Association of petrochemical exposure with spontaneous abortion

OBJECTIVES: To assess the association between petrochemical exposure and spontaneous abortion, a retrospective epidemiological study in a large petrochemical complex in Beijing, China was conducted. METHODS: Plant employment records identified 3105 women who were married, were 20-44 years of age, and had never smoked. Of those, 3070 women (98.8%) reported at least one pregnancy. From this group, 2853 (93%) of the women participated in the study. According to their plant employment record, about 57% of these women workers reported occupational exposure to petrochemicals during the first trimester of their pregnancy. Trained interviewers administered a standardised questionnaire to this group of women and their husbands, collecting information on reproductive history, pregnancy outcomes, employment history, occupational exposure, smoking habits, alcohol consumption, indoor air pollution, and demographic variables. The results from the womens' first pregnancies were analysed. RESULTS: There was a significantly increased risk of spontaneous abortion for women working in all of the production plants with frequent exposure to petrochemicals (8.8%; range of 5.8%-9.8%) compared with those working in nonchemical plants (2.2%; range of 0.0%-7.1%). Also, when a comparison was made between exposed and non-exposed groups within each plant, exposure to petrochemicals was consistently associated with an increased risk of spontaneous abortion. The overall odds ratio (OR) was 2.7 (95% confidence interval (95% CI) 1.8 to 3.9) after adjusting for potential confounders. When the analysis was performed with the exposure information obtained from the women' interview responses for (self reported) exposures, the estimated OR for spontaneous abortions was 2.9 (95% CI 2.0 to 4.0). The analysis was repeated by excluding those 452 women who provided inconsistent reports between recalled exposure and work history, and a comparable risk of spontaneous abortion (OR 2.9; 95% CI 2.0 to 4.4) was found. In analyses for exposure to specific chemicals, an increased risk of spontaneous abortion was found with exposure to most chemicals, and the results for benzene (OR 2.5; 95% CI 1.7 to 3.7), gasoline (OR 1.8; 95% CI 1.1 to 2.9), and hydrogen sulphide (OR 2.3; 95% CI 1.2 to 4.4) were significant. CONCLUSION: An increased risk of spontaneous abortion was found associated with the exposure to petrochemicals, including benzene, gasoline, and hydrogen sulphide.

 

     

Exposure to phenoxy herbicides and the risk of spontaneous abortion.

The Ontario Farm Family Health Study was designed to assess retrospectively the potential adverse effects of exposure to pesticides on pregnancy. Information on the health and life style of approximately 2,000 farm couples, as well as a history of use of pesticides on the farm, was collected by questionnaire. This analysis focuses on pre- and postconception exposure to phenoxy herbicides and the risk of spontaneous abortion using the complete (to date) pregnancy history for each woman. Preconception exposure (from 3 months before conception to the month of conception) was weakly associated with the risk of spontaneous abortion at <20 weeks' gestation [adjusted odds ratio (OR) = 1.1; 95% confidence interval (CI) = 0.6-1.9]. When the analyses were restricted to spontaneous abortions of <12 weeks, the risk was more than doubled (adjusted OR = 2.5; 95% CI = 1.0-6.4), but the results were sensitive to the cutpoint used. If the husband did not normally wear protective equipment during application, the crude OR for early spontaneous abortions was 5.0 (95% CI = 0.7-36.2). Exposure to phenoxy herbicides during the first trimester was generally not associated with increased risk of spontaneous abortion. The results suggest a possible role of preconception (possibly paternal) exposures to phenoxy herbicides in the risk of early spontaneous abortions.     

Subfertility and risk of spontaneous abortion

OBJECTIVES: The purpose of this study was to assess the association between subfertility and spontaneous abortion. METHODS: A total of 1572 women in New York and Vermont reported 3269 pregnancies between 1980 and 1990 and were able to provide an estimate of the waiting time to conception for 2967. Subfertility was defined as a delay of 1 year or more before a recognized conception was achieved. Rates of spontaneous abortion were determined among women with and without subfertility, and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated via multiple logistic regression. RESULTS: Spontaneous abortion rates were 23.0% in pregnancies preceded by subfertility and 14.0% in pregnancies without impaired fertility (adjusted OR = 1.71, 95% CI = 1.26, 2.94). The attributable risk of spontaneous abortion associated with subfertility was 6.2%. CONCLUSIONS: Subfertile women evidence an increased number of spontaneous abortions.     

Spontaneous abortion and work with visual display units.

OBJECTIVE--To determine whether women who work with visual display units are at increased risk of spontaneous abortion. DESIGN--Case-control study. SETTING--Women were recruited during the three years 1987-9 from the Royal Berkshire Hospital in Reading, and from a large group practice situated within the hospital's catchment area. SUBJECTS--Cases were 150 nulliparous working women with a clinically diagnosed spontaneous abortion and controls were 297 nulliparous working women attending for antenatal care. MAIN OUTCOME MEASURES--Cases and controls were contacted and personally interviewed using the same structured questionnaire. Exposure to visual display units (VDUs) at work was assessed from information supplied at interview. RESULTS--No evidence of an increased risk of spontaneous abortion was found in women who reported that they used a VDU at work compared with women who reported that they did not (odds ratio (OR) = 0.9, 95% confidence interval (95% CI) = 0.6-1.4); and no relation with the amount of time spent actively using a VDU was evident (OR = 0.9, 95% CI = 0.5-1.6 for women who worked with a VDU for 21 hours or more each week). No effect of passive exposure to VDUs at work was found (OR = 0.9, 95% CI = 0.6-1.6 for women who reported working less than 10 feet away from a VDU that was usually switched on). These findings were not explained by maternal age, marital state, housing tenure, partner's social class, educational level, smoking, alcohol consumption, or number of previous spontaneous abortions. CONCLUSION--Given the findings and their consistency with the results from other recent studies it is concluded that pregnant women who work with VDUs are not at increased risk of clinically diagnosed spontaneous abortion. For the many women who use VDUs in their jobs, this finding provides reassurance.     

Spontaneous abortion and work with visual display units.

OBJECTIVE--To determine whether women who work with visual display units are at increased risk of spontaneous abortion. DESIGN--Case-control study. SETTING--Women were recruited during the three years 1987-9 from the Royal Berkshire Hospital in Reading, and from a large group practice situated within the hospital's catchment area. SUBJECTS--Cases were 150 nulliparous working women with a clinically diagnosed spontaneous abortion and controls were 297 nulliparous working women attending for antenatal care. MAIN OUTCOME MEASURES--Cases and controls were contacted and personally interviewed using the same structured questionnaire. Exposure to visual display units (VDUs) at work was assessed from information supplied at interview. RESULTS--No evidence of an increased risk of spontaneous abortion was found in women who reported that they used a VDU at work compared with women who reported that they did not (odds ratio (OR) = 0.9, 95% confidence interval (95% CI) = 0.6-1.4); and no relation with the amount of time spent actively using a VDU was evident (OR = 0.9, 95% CI = 0.5-1.6 for women who worked with a VDU for 21 hours or more each week). No effect of passive exposure to VDUs at work was found (OR = 0.9, 95% CI = 0.6-1.6 for women who reported working less than 10 feet away from a VDU that was usually switched on). These findings were not explained by maternal age, marital state, housing tenure, partner's social class, educational level, smoking, alcohol consumption, or number of previous spontaneous abortions. CONCLUSION--Given the findings and their consistency with the results from other recent studies it is concluded that pregnant women who work with VDUs are not at increased risk of clinically diagnosed spontaneous abortion. For the many women who use VDUs in their jobs, this finding provides reassurance.     

Factors associated with contraceptive nonuse among US women ages 35-44 years at risk of unwanted pregnancy

Background

Women ages 35 years and older have the greatest proportion of contraceptive nonuse and unintended pregnancies ending in abortion.

Study Design

We conducted a population-based case-control study among women ages 35-44 years at risk of unwanted pregnancy using the National Survey of Family Growth (NSFG) data to investigate risk factors for contraceptive nonuse.

Results

At last intercourse, 9.8% of women reported not using any contraceptive method. Contraceptive nonusers, as compared to users, were more likely to be ages 40-44 years (OR=2.0, 95% CI 1.1-3.7), foreign-born (OR=4.3, 95% CI 1.9-9.7), black (OR=2.8, 95% CI 1.1-7.0), with household incomes 100-249% of the federal poverty level (FPL) (OR=2.5, 95% CI 1.1-5.8). Women who received contraceptive counseling in the past year had an 80% decreased risk of nonuse (95% CI 0.1-0.5).

Conclusion

Public health strategies to reduce unintended pregnancy, particularly among women ages 35 years and older, should focus on addressing disparities in contraceptive use and promoting contraceptive counseling.     

Risks of repeated miscarriage

There is a lack of well-designed epidemiological studies of possible risk factors for repeated miscarriage. In this Swedish population-based case-control study, we investigated the association between sociodemographic and anthropometric factors, obstetric history and life-style factors, with respect to the risks of first-trimester repeated miscarriage. Information on maternal characteristics was collected through in-person interviews. Plasma blood samples were analysed for cotinine and folate concentrations. Adjusted odds ratios (OR) with 95% confidence interval [CI] were used to estimate the relative risk of repeated miscarriage. The risks of repeated miscarriage were increased for women aged > or = 35 years (adjusted OR 2.9 [95% CI 1.4, 5.8]), as well as for women aged < or = 24 years (OR 2.8 [95% CI 1.1, 6.8]). Women with a history of at least one preceding miscarriage prior to the two index pregnancies, women reporting prolonged time to conceive, and women with a history of myoma, faced a more than fourfold increased risk of repeated miscarriage. Smokers were at an increased risk of repeated miscarriage (OR 2.1 [95% CI 1.1, 4.1]). Among non-smoking women with high caffeine intake, there was an increased risk of repeated miscarriage, whereas there was no such association among smokers. Low plasma folate levels were not associated with increased risks.     

Work schedule during pregnancy and spontaneous abortion

BACKGROUND: There is inconsistent evidence as to whether work schedule (including rotating shifts and night work) can affect reproductive outcomes. METHODS: We investigated the association between work schedule and risk of spontaneous abortion in U.S. nurses. The Nurses' Health Study II is a prospective cohort study established in 1989. In 2001, information about occupational activities and exposures during pregnancy was collected from female nurses for the most recent pregnancy since 1993. Of 11,178 eligible respondents, 9547 (85%) indicated willingness to participate in the occupational study, and 8461 of those (89%) returned the questionnaire, for an overall participation rate of 76%. Of these, 7688 women had pregnancies that were eligible for analysis. RESULTS: Participants reported 6902 live births and 786 (10%) spontaneous abortions. Compared with women who reported usually working "days only" during their first trimester, women who reported usually working "nights only" had a 60% increased risk of spontaneous abortion (RR = 1.6; 95% confidence interval [CI] = 1.3-1.9). A rotating schedule, with or without night shifts, was not associated with an increase in risk (RR = 1.2 [CI = 0.9-1.5] and 1.0 [CI = 0.8-1.2], respectively). Women who reported working more than 40 hours per week during the first trimester were also at increased risk of spontaneous abortion (1.5; 1.3-1.7) compared with women working 21-40 hours, even after adjustment for work schedule. CONCLUSIONS: Nightwork and long work hours may be associated with an increased risk of spontaneous abortion. Further studies are needed to determine whether hormonal disturbances attributed to night work affect pregnancy outcome.     

低浓度芳香烃溶剂暴露对自然流产影响的基因多态性研究

目的 探讨女工芳香烃溶剂暴露和细胞色素P450氧化酶MSP1基因和谷胱甘肽S转移酶GSTM1基因的多态性对自然流产的影响。方法 采用回顾性流行病学调查方法。使用统一调查表，由经过培训的调查员在北京燕山地区调查了276个女工，其中有自然流产史者58人，无自然流产史者218人。结果 单因素分析发现；GSTM1缺失基因型可致女工自然流产的危险度显著增加[OR=2.07(95%CI:1.15-3.71)]，但未观察到MSP1基因及芳香烃溶剂暴露对女工自然流产的影响，采用多元Logistic回归模型。经文化程度，年龄，倒班，体重指数，被动吸烟，职业紧张混杂因素调整后，可见GSTM1缺失基因型能显著致女工自然流产危险度增加[OR=2.15(95%CI;1.17-3.98)]。以GSTM1存在基因型和MSP1野生基因型为参照组。采用多元Logistic回归模型。并将文化程度，年龄，倒班，体重指数，被动吸烟，职业紧张混杂因素放入回归模型进行调整，在调整混杂因素前后，与参照组比较，均可见MSP1杂合子/突变基因型合并GSTM1缺失基因型使女工自然流失基因型与MSP1突变纯合子/杂合子基因型之间对自然流产的影响存在相加的联合作用。     

An exploratory analysis of the effect of pesticide exposure on the risk of spontaneous abortion in an Ontario farm population

The toxicity of pesticides on human reproduction is largely unknown--particularly how mixtures of pesticide products might affect fetal toxicity. The Ontario Farm Family Health Study collected data by questionnaire on the identity and timing of pesticide use on the farm, lifestyle factors, and a complete reproductive history from the farm operator and eligible couples living on the farm. A total of 2,110 women provided information on 3,936 pregnancies, including 395 spontaneous abortions. To explore critical windows of exposure and target sites for toxicity, we examined exposures separately for preconception (3 months before and up to month of conception) and postconception (first trimester) windows and for early (< 12 weeks) and late (12-19 weeks) spontaneous abortions. We observed moderate increases in risk of early abortions for preconception exposures to phenoxy acetic acid herbicides [odds ratio (OR) = 1.5; 95% confidence interval (CI), 1.1-2.1], triazines (OR = 1.4; 95% CI, 1.0-2.0), and any herbicide (OR = 1.4; 95% CI, 1.1-1.9). For late abortions, preconception exposure to glyphosate (OR = 1.7; 95% CI, 1.0-2.9), thiocarbamates (OR = 1.8; 95% CI, 1.1-3.0), and the miscellaneous class of pesticides (OR = 1.5; 95% CI, 1.0-2.4) was associated with elevated risks. Postconception exposures were generally associated with late spontaneous abortions. Older maternal age (> 34 years of age) was the strongest risk factor for spontaneous abortions, and we observed several interactions between pesticides in the older age group using Classification and Regression Tree analysis. This study shows that timing of exposure and restricting analyses to more homogeneous endpoints are important in characterizing the reproductive toxicity of pesticides.     

Cancer incidence in airline cabin crew: experience from Sweden

Aims: To determine the cancer incidence in Swedish cabin crew.

Methods: Cancer incidence of cabin crew at the Swedish Scandinavian Airline System (SAS) (2324 women and 632 men) employed from 1957 to 1994 was determined during 1961–96 from the Swedish National Cancer Register. The cancer incidence in cabin crew was compared with that of the general Swedish population by comparing observed and expected number of cases through standardised incidence ratios (SIR). A nested case-control study was performed, including cancer cases diagnosed after 1979 and four controls per case matched by gender, age, and calendar year.

Results: The SIR for cancer overall was 1.01 (95% CI 0.78 to 1.24) for women and 1.16 (95% CI 0.76 to 1.55) for men. Both men and women had an increased incidence of malignant melanoma of the skin (SIR 2.18 and 3.66 respectively) and men of non-melanoma skin cancer (SIR 4.42). Female cabin attendants had a non-significant increase of breast cancer (SIR 1.30; 95% CI 0.85 to 1.74). No clear associations were found between length of employment or cumulative block hours and cancer incidence.

Conclusions: Swedish cabin crew had an overall cancer incidence similar to that of the general population. An increased incidence of malignant melanoma and non-melanoma skin cancer may be associated with exposure to UV radiation, either at work or outside work. An increased risk of breast cancer in female cabin crew is consistent with our results and may in part be due to differences in reproductive history.

     

Relations of gestational length and timing and type of incomplete pregnancy to ovarian cancer risk

While the protective nature of parity with respect to ovarian cancer has been well documented, whether a history of incomplete pregnancy affects ovarian cancer risk is uncertain. Data collected from 739 epithelial ovarian cancer cases and 1,313 community controls in the Delaware Valley from 1994 to 1998 were used to evaluate the relation between gestational length and timing of first induced or spontaneous abortion and ovarian cancer risk. Incomplete pregnancy was not associated with ovarian cancer among nulliparous women or among ever-pregnant women either before or after adjustment for relevant confounders (for nulliparous women, odds ratio (OR) = 1.12, 95% confidence interval (CI): 0.66, 1.89; for ever-pregnant women, OR = 0.95, 95% CI: 0.76, 1.18). Among unigravid women, one full-term pregnancy was more protective than an incomplete pregnancy (adjusted OR = 0.29, 95% CI: 0.15, 0.57). These results were independent of the type of pregnancy loss. Among ever-pregnant women, a spontaneous abortion before a first birth provided significant protection (adjusted OR = 0.47, 95% CI: 0.30, 0.75), while no significant effect was found for an induced abortion prior to a first birth (adjusted OR = 0.80, 95% CI: 0.44, 1.47). These data do not support an independent association between incomplete pregnancies, either spontaneous or induced, and ovarian cancer risk.