Maternal medication use and the risk of brain tumors in the offspring: the SEARCH international case-control study

N-nitroso compounds (NOC) have been associated with carcinogenesis in a wide range of species, including humans. There is strong experimental data showing that nitrosamides (R(1)NNO.COR(2)), a type of NOC, are potent neuro-carcinogens when administered transplacentally. Some medications are a concentrated source of amides or amines, which in the presence of nitrites under normal acidic conditions of the stomach can form NOC. Therefore, these compounds, when ingested by women during pregnancy, may be important risk factors for tumors of the central nervous system in the offspring. The aim of the present study was to test the association between maternal use of medications that contain nitrosatable amines or amides and risk of primary childhood brain tumors (CBT). A case-control study was conducted, which included 1,218 cases and 2,223 population controls, recruited from 9 centers across North America, Europe and Australia. Analysis was conducted for all participants combined, by tumor type (astroglial, primitive neuroectodermal tumors and other glioma), and by age at diagnosis (< or =5 years; >5 years). There were no significant associations between maternal intake of medication containing nitrosatable amines or amides and CBT, for all participants combined and after stratification by age at diagnosis and histological subtype. This is the largest case-control study of CBT and maternal medications to date. Our data provide little support for an association between maternal use of medications that may form NOC and subsequent development of CBT in the offspring.     

Antenatal risk factors for malignant brain tumours in new south wales children

A population-based case-control study of incident primary malignant brain tumours diagnosed during 1985 to 1989 in children aged 0 to 14 years was carried out in the coastal conurbation of New South Wales comprising Sydney, Wollon-gong and Newcastle in the period 1988 to 1990. Personal interviews were conducted using a structured questionnaire with mothers of 82 cases and 164 control children individually matched to the cases by sex and age. Among the hypotheses being examined were those related to exposure to parental tobacco smoke, N-nitroso compounds and possible protection from sources of vitamin C. No link was found with tobacco smoking by the mother before or during pregnancy. While exposure during pregnancy of the mother to tobacco smoke of the father appeared to double the risk of childhood brain tumours and a similar risk was found for father (but not mother) smoking before the index pregnancy, there was no “dose-response” and the increased risk was confined to data supplied by the mother (rather than the father himself). The risk of childhood brain tumours rose with reported increasing consumption, during pregnancy, of cured meats, which have high levels of N-nitroso compounds (or their precursors), and fell with rising consumption of vegetables. No association was found between the risk of childhood brain tumours and family history of epilepsy, cancer, or tumours of the nervous system, parental irradiation, previous miscarriage or procedures carried out during pregnancy, maternal consumption of antihistamines, barbiturates or diuretics, or maternal contact with cats or farm-life during pregnancy. © 1994 Wiley-Liss, Inc.     

Cured meat, vegetables, and bean-curd foods in relation to childhood acute leukemia risk: A population based case-control study

Background  

Consumption of cured/smoked meat and fish leads to the formation of carcinogenic N- nitroso compounds in the acidic stomach. This study investigated whether consumed cured/smoked meat and fish, the major dietary resource for exposure to nitrites and nitrosamines, is associated with childhood acute leukemia.     

Epidemiological studies of perinatal carcinogenesis

Epidemiological evidence for prenatal carcinogenesis includes associations between cancer in young people and intrauterine exposure to X-rays, drugs and hormones and prezygotic events such as specific chromosomal aberrations associated with specific cancers. Recent findings suggest that the hormonal environment during early gestation can result not only in the development of clear-cell adenocarcinoma of the vagina but also in the development of germ cell tumours of the testes and ovary. Hormone-related risk factors for testicular germ cell neoplasms include maternal use of exogenous oestrogens during early gestation and, possibly, maternal nausea, maternal obesity and race as well. Ovarian germ cell tumours also appear to be related to maternal use of hormones and obesity. Several epidemiological studies of cancer in young people have been directed towards suggested associations with parental occupational exposures, parental cigarette smoking and household exposures to electric and magnetic fields (EMF). The findings of the many studies of parental occupational exposures are inconsistent and are often nonspecific with respect to the type of childhood cancer and the job exposure implicated. Parental cigarette smoking has been associated in some studies with an increased risk for cancer among children and young adults, and in other studies with an increased risk among mature adults, but the findings are not consistent across studies. Three studies of all types of childhood cancer found risk to be related to household exposures to EMF; in all three, the risk for central nervous system tumours was increased, and in two of the three leukaemia risk as well. A fourth study showed no association between childhood leukaemia and EMF. A hypothesis is proposed which suggests that prenatal and early childhood exposure to N-nitroso compounds (NOC) may be related to the development of primary tumours of the brain in children. Experimentalists have shown that various NOC are potent nervous system carcinogens, particularly when animals are exposed transplacentally. This experimental model and findings from a Los Angeles case-control study (209 pairs) of brain tumours in young people led to the proposed epidemiological hypothesis. Although this and other epidemiological studies of NOC have major limitations, findings from epidemiological studies of congenital defects and of other childhood cancers lend the hypothesis some support. A large international collaborative case-control study of childhood brain tumours was begun recently. This study has a major advantage over most case-control studies in adults because the exposure period of greatest interest (gestation) is clearly defined.     

Maternal residential pesticide use during pregnancy and risk of malignant childhood brain tumors: A pooled analysis of the ESCALE and ESTELLE studies (SFCE)

Some previous epidemiological studies have suggested that pesticide exposure during pregnancy may have a possible role in the development of childhood brain tumors (CBT). We pooled data from two French national population‐based, case–control studies to investigate the association between maternal residential use of pesticides during pregnancy and the risk of CBT. The mothers of 437 CBT cases and 3,102 controls aged under 15 years who resided in France at diagnosis/interview, frequency‐matched by age and gender, answered a structured telephone interview conducted by trained interviewers. Unconditional logistic regression was used to estimate pooled odds ratio (OR) and 95% confidence intervals (95% CI). CBT was significantly associated with the maternal home use of pesticides during pregnancy (OR 1.4, 95% CI 1.2–1.8) and, more specifically, with insecticide (OR 1.4, 1.2–1.8). We could not draw any conclusions about herbicides and/or fungicides because few women used them during pregnancy and most of these mothers also used insecticides. Although potential recall bias cannot be excluded, our findings of this pooled analysis support the hypothesis that residential maternal use of pesticides during pregnancy and particularly insecticides may increase the risk of CBT. Future investigations to verify these findings and to explore for CBT subtypes and dose–response are necessary to have a better understanding of the possible role of pesticides in etiology of CBT.     

Maternal smoking during pregnancy and the risk of childhood brain tumors: a meta-analysis of 6566 subjects from twelve epidemiological studies

Objective: Prior epidemiological studies suggest a possible association between maternal smoking during pregnancy and risk of childhood brain tumors. A meta-analysis was performed statistically pooling all available observational studies on this topic in order to evaluate this suspected association. Methods: Using previously described methods, a protocol was developed for a meta-analysis examining the association between maternal smoking during pregnancy and subsequent development of primary brain tumors in their offspring. Literature search techniques, study inclusion criteria and statistical procedures were prospectively defined. Data from epidemiological studies were pooled using a general variance-based meta-analytic method employing confidence intervals previously described by Greenland. The outcome of interest was a summary relative risk (RR_s) reflecting the risk of childhood brain tumor development associated with mother's smoking during the index pregnancy. Sensitivity analyses were performed when necessary to explain any observed statistical heterogeneity and/or to evaluate the impact of demographic or study characteristics on the summary estimate of effect. Results: Twelve observational studies meeting protocol specified inclusion criteria were obtained via a comprehensive literature search. These studies enrolled a total of 6566 patients. Analysis for homogeneity demonstrated that the data were homogeneous (P>0.50) and could be statistically combined. Pooling all twelve reports yielded an RR_s of 1.05 (0.90–1.21), a non-statistically significant result suggesting no clear association between maternal smoking during pregnancy and risk of childhood brain tumor development. Numerous sensitivity analyses examining the possible effect of study design and various patient characteristics failed to show any influence on the RR_s further supporting the observed lack of association. Conclusion: The available epidemiological data do not support a clear association between maternal smoking during pregnancy and pediatric brain tumor development. Although it appears likely that no association exists, limitations in study designs limit definitive conclusions based on available data.     

Ingested nitrate and nitrite,disinfection by‐products,and pancreatic cancer risk in postmenopausal women

Nitrate and nitrite are precursors of N‐nitroso compounds (NOC), probable human carcinogens that cause pancreatic tumors in animals. Disinfection by‐products (DBP) exposures have also been linked with digestive system cancers, but few studies have evaluated relationships with pancreatic cancer. We investigated the association of pancreatic cancer with these drinking water contaminants and dietary nitrate/nitrite in a cohort of postmenopausal women in Iowa (1986–2011). We used historical monitoring and treatment data to estimate levels of long‐term average nitrate and total trihalomethanes (TTHM; the sum of the most prevalent DBP class) and the duration exceeding one‐half the maximum contaminant level (>½ MCL; 5 mg/L nitrate‐nitrogen, 40 µg/L TTHM) among participants on public water supplies (PWS) >10 years. We estimated dietary nitrate and nitrite intakes using a food frequency questionnaire. We computed hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression and evaluated nitrate interactions with smoking and vitamin C intake. We identified 313 cases among 34,242 women, including 152 with >10 years PWS use (N = 15,710). Multivariable models of average nitrate showed no association with pancreatic cancer (HR_{p95 vs. Q1} = 1.16, 95% CI: 0.51–2.64). Associations with average TTHM levels were also null (HR_{Q4 vs. Q1} = 0.70, 95% CI:0.42–1.18). We observed no trend with increasing years of exposure to either contaminant at levels >½ MCL. Positive associations were suggested in the highest dietary nitrite intake from processed meat (HR_{p95 vs. Q1} = 1.66, 95% CI 1.00–2.75;p_trend = 0.05). We found no interactions of nitrate with known modifiers of endogenous NOC formation. Our results suggest that nitrite intake from processed meat may be a risk factor for pancreatic cancer.     

Smoking in pregnancy and risk of cancer among young children: A population‐based study

Smoking during pregnancy is a plausible risk factor for childhood cancer, yet previous studies have yielded conflicting results, and few prospective studies have been published. Data on maternal smoking were obtained from California birth certificates. We linked California birth certificates (births 2007–2011) with California Cancer Registry records for childhood cancer cases (diagnosed January 2007–September 2013) that were ages 5 or younger at diagnosis (N cases = 2,021). Controls (N = 40,356) were frequency‐matched by birth year and randomly selected from birth certificate records. We used unconditional logistic regression to obtain odds ratios (OR) and 95% confidence intervals (CI) to assess the association between smoking during pregnancy and childhood cancer. We observed positive associations for gliomas (OR = 1.8, 95% CI: 1.0–3.4) and retinoblastoma (OR = 3.0, 95% CI: 1.4–6.6), particularly bilateral retinoblastoma (OR = 9.4, 95% CI 3.6–24.7) with maternal smoking in pregnancy. Maternal smoking during pregnancy may be a risk factor for retinoblastoma and certain types of childhood brain tumors.     

N-nitroso compounds and human intracranial tumours

Experimentalists have shown that various N-nitroso compounds are potent nervous system carcinogens, particularly when animals are exposed transplacentally. Information has been obtained concerning exposure to N-nitroso compounds and their precursors in three case-control studies of intracranial tumour patients in Los Angeles County, California. A study of women (185 pairs) found that level of consumption of nitrite-cured meats was related to meningioma development (p = 0.01). In a similar study of meningiomas in men (105 pairs), the association with cured meats was not clear. The most striking results were obtained in a study of young brain tumour patients (209 matched pairs). Increased risk was associated with maternal contact, during pregnancy, with N-nitrosamine-containing substances, such as burning incense (odds ratio, 3.3; p less than 0.01), sidestream cigarette smoke (odds ratio, 1.5; p = 0.03) and face make-up (odds ratio, 1.6; p = 0.02). Increased risk was also associated with maternal use of diuretics (odds ratio, 2.0; p = 0.03) and antihistamines (odds ratio, 3.4; p less than 0.01) and with the level of maternal consumption of cured meats (p less than 0.01). Diuretics and antihistamines contain nitrosatable amines and amides, and cured meats contain nitrites - chemicals which are precursors of N-nitroso compounds. Additional epidemiological studies of nervous system tumours in young people would appear to offer considerable promise for testing the hypothesis that N-nitroso compounds are etiologically related to human neurogenic neoplasms.     

Epidemiological evidence for the role of nitroso compounds in human cancer

Human exposure to N-nitroso compounds (NOC) is not to single compounds but to highly complex mixtures such as food or tobacco products which may contain various NOC, NOC precursors and modulators of NOC metabolism in addition to other known carcinogens. Aetiological models also stress the importance of other cofactors. The interrelationship of these cofactors with relevant NOC exposures and the possible influence of confounding factors need to be considered in order to evaluate the risk related to NOC. This task is made more difficult because the levels of human NOC exposure are often low, and some of the relevant exposure is likely to be from endogenously formed NOC. Nonetheless, current hypotheses reviewed here propose a role for NOC in the aetiology of tobacco-related cancers and of cancers of the bladder, stomach, oesophagus and brain. Data implicating tobacco-specific nitrosamines in the aetiology of cancers of the oral cavity among snuff dippers is most convincing. Evidence from epidemiological studies in support of other NOC/cancer hypotheses is circumstantial and much work remains to be done to define the role of NOC and develop strategies for prevention of these tumours.     

Dietary sources of N‐nitroso compounds and bladder cancer risk: Findings from the Los Angeles bladder cancer study

N‐Nitroso compounds (NOCs) have been proposed as possible bladder carcinogens. The main sources of exogenous exposure to NOCs are cigarette smoke and diet, particularly processed (i.e., nitrite‐treated) meats. Perhaps more importantly, NOCs can be formed endogenously from dietary precursors such as nitrate, nitrite and amines. Heme has been shown to increase endogenous nitrosation. We examined the role of dietary sources of NOCs and NOC precursors as potential bladder cancer risk factors using data from the Los Angeles Bladder Cancer Study, a population‐based case‐control study. Dietary and demographic information was collected from 1,660 bladder cancer cases and 1,586 controls via a structured questionnaire. Intake of liver and of salami/pastrami/corned beef, were both statistically significantly associated with risk of bladder cancer in this study, particularly among nonsmokers. Heme intake was also statistically significantly associated with risk of bladder cancer among nonsmokers only. When considering NOC precursors, risk was consistently higher among subjects with concurrent high intake of nitrate and high intake of the different meats (sources of amines and nitrosamines). Results of this study are consistent with a role of dietary sources of NOC precursors from processed meats in bladder cancer risk, suggesting consumption of meats with high amine and heme content such as salami and liver as a risk factor for bladder cancer. In addition, any effect of consuming these meats may be greater when accompanied by high nitrate intake.     

Human exposure to endogenous N-nitroso compounds: quantitative estimates in subjects at high risk for cancer of the oral cavity, oesophagus, stomach and urinary bladder

A sensitive procedure to quantitate human exposure to endogenous N-nitroso compounds (NOC) has been developed. It is based on the excretion of N-nitrosoproline (NPRO) and other N-nitrosamino acids in the urine, which are measured as an index of endogenous nitrosation, following ingestion of precursors. The NPRO test has been applied to human subjects in clinical and epidemiological studies, and the kinetics and dietary modifiers of endogenous nitrosation have been investigated. Results obtained after application of the NPRO test to subjects at high risk for cancers of the stomach, oesophagus, oral cavity and urinary bladder are summarized. In most instances, higher exposures to endogenous NOC were found in high-risk subjects, but individual exposure was greatly affected by dietary modifiers or disease state. Vitamin C efficiently lowered the body burden of intragastrically formed NOC. The results point to an aetiological role of NOC in these human cancers and provide an interpretation of epidemiological findings that have shown protective effects of fruits and vegetables against several malignancies.     

Dietary nitrate and nitrite intake and risk of colorectal cancer in the Shanghai Women's Health Study

Nitrate and nitrite are precursors of endogenously formed N‐nitroso compounds (NOC), known animal carcinogens. Nitrosation reactions forming NOCs can be inhibited by vitamin C and other antioxidants. We prospectively investigated the association between dietary nitrate and nitrite intake and risk of colorectal cancer in the Shanghai Women's Health Study, a cohort of 73,118 women ages 40–70 residing in Shanghai. We evaluated effect modification by factors that affect endogenous formation of NOCs: vitamin C (at or above/below median) and red meat intake (at or above/below median). Nitrate, nitrite and other dietary intakes were estimated from a 77‐item food frequency questionnaire administered at baseline. Over a mean of 11 years of follow‐up, we identified 619 colorectal cancer cases (n = 383, colon; n = 236, rectum). Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard regression. Overall, nitrate intake was not associated with colorectal cancer risk (HR = 1.08; 95% CI: 0.73–1.59). However, among women with vitamin C intake below the median (83.9 mg day^?1) and hence higher potential exposure to NOCs, risk of colorectal cancer increased with increasing quintiles of nitrate intake (highest vs. lowest quintile HR = 2.45; 95% CI: 1.15–5.18; p trend = 0.02). There was no association among women with higher vitamin C intake. We found no association between nitrite intake and risk of colorectal cancer overall or by intake level of vitamin C. Our findings suggest that high dietary nitrate intake among subgroups expected to have higher exposure to endogenously formed NOCs increases risk of colorectal cancer.     

Exposure to pesticides and the risk of childhood brain tumors

Purpose

Previous research has suggested positive associations between parental or childhood exposure to pesticides and risk of childhood brain tumors (CBT). This Australian case–control study of CBT investigated whether exposures to pesticides before pregnancy, during pregnancy and during childhood, were associated with an increased risk.

Methods

Cases were recruited from 10 pediatric oncology centers, and controls by random-digit dialing, frequency matched on age, sex, and State of residence. Exposure data were collected by written questionnaires and telephone interviews. Data were analyzed by unconditional logistic regression.

Results

The odds ratios (ORs) for professional pest control treatments in the home in the year before the index pregnancy, during the pregnancy, and after the child’s birth were 1.54 (95 % confidence interval (CI): 1.07, 2.22), 1.52 (95 % CI: 0.99, 2.34) and 1.04 (95 % CI: 0.75, 1.43), respectively. ORs for treatments exclusively before pregnancy and during pregnancy were 1.90 (95 % CI: 1.08, 3.36) and 1.02 (95 % CI: 0.35, 3.00), respectively. The OR for the father being home during the treatment was 1.79 (95 % CI: 0.85, 3.80). The OR for paternal occupational exposure in the year before the child’s conception was 1.36 (95 % CI: 0.66, 2.80). ORs for prenatal home pesticide exposure were elevated for low- and high-grade gliomas; effect estimates for other CBT subtypes varied and lacked precision.

Conclusions

These results suggest that preconception pesticide exposure, and possibly exposure during pregnancy, is associated with an increased CBT risk. It may be advisable for both parents to avoid pesticide exposure during this time.     

Exposure to household painting and floor treatments,and parental occupational paint exposure and risk of childhood brain tumors: results from an Australian case–control study

Purpose

Childhood brain tumors (CBT) are the leading cause of cancer death in children, yet their etiology remains largely unknown. This study investigated whether household exposure to paints and floor treatments and parental occupational painting were associated with CBT risk in a population-based case–control study conducted between 2005 and 2010.

Methods

Cases were identified through all ten Australian pediatric oncology centers, and controls via nationwide random-digit dialing, frequency matched to cases on age, sex, and state of residence. Data were obtained from parents in mailed questionnaires and telephone interviews. Information on domestic painting and floor treatments, and parental occupational exposure to paint, in key periods relating to the index pregnancy and childhood was obtained for 306 cases and 950 controls. Data were analyzed using unconditional logistic regression, adjusting for frequency matching variables and potential confounders.

Results

Overall, we found little evidence that parental, fetal, or childhood exposure to home painting or floor treatments was associated with risk of CBT. There was, though, some evidence of a positive association between childhood exposure to indoor painting and risk of high-grade glioma [odds ratio (OR) 3.31, 95 % confidence interval (CI) 1.29, 8.52] based on very small numbers. The OR for the association between CBT and paternal occupational exposure to paint any time before the pregnancy was 1.32 (95 % CI 0.90, 1.92), which is consistent with the results of other studies.

Conclusions

Overall, we found little evidence of associations between household exposure to paint and the risk of CBT in any of the time periods investigated.     

Childhood and parental diagnostic radiological procedures and risk of childhood brain tumors

Purpose

Childhood brain tumors (CBT) are the second most common type of childhood cancer and the leading cause of childhood cancer mortality. Few causes of CBT are known, but parental, fetal, and early life exposures are likely to be important given the early age at diagnosis of many cases. We aimed to investigate whether parents' diagnostic radiological procedures before conception, in the mother during pregnancy or the child’s procedures were associated with an increased risk of CBT.

Methods

This population-based case–control study was conducted between 2005 and 2010. Cases were identified through all ten Australian pediatric oncology centers, and controls via nationwide random-digit dialing; frequency-matched to cases on age, sex and state of residence. Information on radiological exposures in the time periods of interest was obtained for 306 case and 950 control families through mailed questionnaires. Analysis used unconditional logistic regression, adjusting for matching variables and potential confounders.

Results

We found no evidence of positive associations between risk of CBT overall and childhood or parental pre-pregnancy radiological procedures. Increased ORs for high-grade gliomas associated with childhood radiological procedures were based on small numbers and may be due to chance.

Conclusions

Given the evidence for an increased risk of CBT in cohort studies of computed tomography (CT) in childhood, the lack of such an association in our study may be due to the reduced intensity of CTs after 2001. Future research to investigate the safety of fetal exposure to more intense procedures like CT scans is needed.     

Maternal smoking during pregnancy and risk of brain tumors in the offspring. A prospective study of 1.4 million Swedish births

Objective: Studies of the effect of maternal smoking during pregnancy on development of brain tumors in the offspring generally have found no increase in risk but most have mainly relied on retrospective exposure assessment. We conducted a prospective study on a large birth cohort in Sweden. Methods: Women giving birth during 1983–1997 were classified as smokers or non-smokers based on information ascertained at the first prenatal visit and recorded in the Swedish Birth Register. Follow-up of brain tumor incidence among offspring through 1997 was achieved by linkage with the Swedish Cancer Register. Hazard ratios were estimated using Cox proportional hazard regression, adjusting for demographic characteristics available in the Birth Register. Results: Brain tumors (n = 480) occurred at a rate of 4.5 cases per 100,000 person-years. Children of women who smoked during pregnancy had an increased incidence of brain tumors (hazard ratio = 1.24; 95% confidence interval: 1.01–1.53). The increase in risk was similar for benign and malignant tumors, and was most apparent for astrocytoma. The effect of smoking on the occurrence of brain tumors was seen most strongly among 2–4 year-old children. Conclusions: These results support a role for maternal smoking during pregnancy in the etiology of childhood brain tumors. Our findings should be confirmed in other prospective studies.     

Nitrate in public water supplies and the risk of renal cell carcinoma

Drinking water and dietary sources of nitrate and nitrite can react in vivo with amines and amides to form N-nitroso compounds (NOC), potent animal carcinogens. Nitrate is a widespread contaminant of drinking water supplies especially in agricultural areas. We conducted a population-based case–control study of renal cell carcinoma in 1986–1989 in Iowa, a state with elevated levels in many public water supplies. We collected a lifetime water source history, but due to limited monitoring data, most analyses focused on the subpopulation, who used Iowa public supplies with nitrate measurements (actual or imputed data) for ≥70% of their person-years since 1960 (201 cases, 1,244 controls). We computed the average nitrate level and years using a public supply with nitrate levels >5 and >10 mg/l. Dietary nitrate and nitrite were estimated from a 55-item food frequency questionnaire. There was no association of renal cell carcinoma with the average nitrate level and years using public supplies >5 and >10 mg/l nitrate-nitrogen (10+ years >5 mg/l odds ratio (OR) = 1.03, 95% confidence interval (CI) 0.66, 1.60). However, higher nitrate exposure was associated with an increased risk among subgroups with above the median red meat intake (10+ years >5 mg/l OR = 1.91, 95% CI 1.04–3.51) or below the median vitamin C intake (10+ years >5 mg/l OR = 1.90, 95% CI 1.01, 3.56), dietary factors that increase the endogenous formation of NOC. Exclusion of long-term Des Moines residents, a large proportion of the high exposure categories, attenuated the association. These findings deserve additional study in populations with high water nitrate intake and information on dietary intakes. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Parental occupations and childhood brain tumors: results of an international case–control study

Objective: To evaluate the role of parental occupations in the etiology of childhood brain tumors (CBT). Methods: Population-based case–control studies were conducted concurrently in seven countries under the coordination of the International Agency for Research on Cancer, gathering 1218 cases and 2223 controls. We report here the findings related to parental occupations during the 5-year period before the child's birth. Risk estimates related to a number of paternal and maternal occupations were obtained by unconditional logistic regression adjusted for age, sex, year of birth, and center, for all types of CBT combined and for the subgroups of astroglial, primitive neuroectodermal tumors (PNET), and other glial tumors. Results: An increased risk in relation with agricultural work was seen for all CBT combined and for other glial tumors. Increased risks for all tumors and PNET were seen for paternal occupation as an electrician; the same pattern held for maternal occupation when children under 5 were selected. Paternal occupation as a driver or mechanic, and maternal work in an environment related to motor-vehicles were associated with an increased risk for all CBT and astroglial tumors. More case mothers compared to control mothers were employed in the textile industry. Conclusion: Our study reinforces previous findings relative to the role of parental work in agriculture, electricity, or motor-vehicle related occupations and maternal work in the textile industry. It does not confirm previous associations with work environments including aerospace, the chemical industry, or the food industry, or with maternal occupation as a hairdresser, a nurse, or a sewing machinist, and paternal occupation as a welder.(deceased)     

Childhood brain tumours: associations with parental occupational exposure to solvents

Background:

Parental occupational exposures have been associated with childhood brain tumours (CBT), but results are inconsistent. Few studies have studied CBT risk and parental solvent exposure, suggesting a possible association. We examined the association between CBT and parental occupational exposure to solvents in a case–control study.

Methods:

Parents of 306 cases and 950 controls completed detailed occupational histories. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for both maternal and paternal exposure to benzene, other aromatics, aliphatics and chlorinated solvents in key time periods relative to the birth of their child. Adjustments were made for matching variables (child''s age, sex and state of residence), best parental education and occupational exposure to diesel exhaust.

Results:

An increased risk of CBT was observed with maternal occupational exposures to chlorinated solvents (OR=8.59, 95% CI 0.94–78.9) any time before birth. Paternal exposure to solvents in the year before conception was associated with an increased CBT risk: OR=1.55 (95% CI 0.99–2.43). This increased risk appeared to be mainly attributable to exposure to aromatic solvents: OR=2.72 (95% CI 0.94–7.86) for benzene and OR=1.76 (95% CI 1.10–2.82) for other aromatics.

Conclusions:

Our results indicate that parental occupational exposures to solvents may be related to an increased risk of CBT.