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Adult Brain Cancer

• Farming, Pesticides, and Brain Cancer: A 20-Year Updated Systematic Literature Review and Meta-Analysis
  Twenty additional years of epidemiologic literature have become available since the publication of two meta-analyses on farming and brain cancer in 1998. The current systematic literature review and meta-analysis extends previous research and harmonizes findings. A random effects model was used to calculate meta-effect estimates from 52 studies (51 articles or reports), including 11 additional studies since 1998. Forty of the 52 studies reported positive associations between farming and brain cancer with effect estimates ranging from 1.03 to 6.53. The overall meta-risk estimate was 1.13 (95% CI = 1.06, 1.21), suggesting that farming is associated with a 13% increase in risk of brain cancer morbidity or mortality. Farming among white populations was associated with a higher risk of brain cancer than among non-white populations. Livestock farming (meta-RR = 1.34; 95% CI = 1.18, 1.53) was associated with a greater risk compared with crop farming (meta-RR = 1.13; 95% CI = 0.97, 1.30). Farmers with documented exposure to pesticides had greater than a 20% elevated risk of brain cancer. Despite heterogeneity among studies, we conclude that the synthesis of evidence from 40 years of epidemiologic literature supports an association between brain cancer and farming with its potential for exposure to chemical pesticides.
  [Gatto, N.M., Ogata, P. and Lytle, B. Cancers, 13(17), p.4477.]
• Occupational exposure to pesticides and risk of adult brain tumors.
  A hospital-based case-control study finds that woman with occupational herbicide exposure show an increased risk meningioma compared to woman who never used herbicides (OR 2.4), a significant trend for increasing risk with increasing years of herbicide exposure and increasing cumulative exposure.
  [Samanic, C.M., et al. 2008. American Journal of Epidemiology 167(8):976-985]
• Brain tumours and exposure to pesticides: a case-control study in southwestern France.
  Brain tumours are often disabling and rapidly lethal; their aetiology is largely unknown. Among potential risk factors, pesticides are suspected. To examine the relationship between exposure to pesticides and brain tumours in adults in a population-based case-control study in southwestern France. Between May 1999 and April 2001, 221 incident cases of brain tumours and 442 individually matched controls selected from the general population were enrolled. Histories of occupational and environmental exposures, medical and lifestyle information were collected. A cumulative index of occupational exposure to pesticides was created, based on expert review of lifelong jobs and tasks. Separate analyses were performed for gliomas and meningiomas. A non-statistically significant increase in risk was found for brain tumours when all types of occupational exposure to pesticides were considered (OR = 1.29, 95% CI 0.87 to 1.91) and slightly higher but still non-statistically significant when gliomas were considered separately (OR = 1.47, 95% CI 0.81 to 2.66). In the highest quartile of the cumulative index, a significant association was found for brain tumours (OR = 2.16, 95% CI 1.10 to 4.23) and for gliomas (OR = 3.21, 95% CI 1.13 to 9.11), but not for meningiomas. A significant increase in risk was also seen for the treatment of home plants (OR = 2.24, 95% CI 1.16 to 4.30) owing to environmental exposure to pesticides. These data suggest that a high level of occupational exposure to pesticides might be associated with an excess risk of brain tumours, and especially of gliomas.
  [Provost, D., et al. 2007. Brain tumours and exposure to pesticides: a case-control study in southwestern France. Occupational and Environmental Medicine 64:509-514]
• Agricultural pesticide use and risk of glioma in Nebraska, United States
  In a population-based case-control study in eastern Nebraska, men living or working on a farm for at least 55 years is associated with an almost 4-fold increased risk of glioma. Among male farmers, the study finds an increase risk for glioma for those exposed to herbicides metribuzin and paraquat, insecticides bufencarb and chlorpyrifos and coumaphos.
  [Lee, W., et al. 2005. Occupational and Environmental Medicine 62(11):786-792]
• Occupational risk factors for brain cancer: a population-based case-control study in Iowa
  A population case-control study in Iowa finds a significant increased risk to a type of brain cancer called glioma for women employed in agriculture services or farming.
  [Zheng, T., et al. 2001.Journal of Occupational and Environmental Medicine 43(4): 333-340]
• Occupational Exposure to Carbofuran and the Incidence of Cancer in the Agricultural Health Study
  A geographical study looking at pesticide use and cancer incidence in Costa Rica finds that in areas of mainly coffee production there are elevated number of brain cancers, particularly for men; it also found that for rural counties with heavy pesticide use there is an association with an increase risk for brain cancer in females.
  [Wesseling, C., et al. 1999. International Journal of Epidemiology 28: 365-374]
• Brain cancer mortality among French farmers: the vineyard pesticide hypothesis.
  In this study, the authors assessed the contribution of vineyard pesticides to brain cancer mortality among agricultural workers. A pesticide exposure index (PEI) in vineyards was calculated for 89 French geographical units (départements). The authors estimated standardized mortality ratios among male farmers and farm laborers aged 35-74 y for the years 1984-1986. Poisson regression models, which were fitted to the ecological data, included random effects. Mortality from brain cancer among farmers was significantly higher than mortality for the overall population (standardized mortality ratio = 1.25, p < .001). Univariate analysis revealed a significant link with pesticide exposure in vineyards (relative risk = 1.10; 95% confidence interval = 1.03, 1.18), as did multivariate analysis (relative risk = 1.11; 95% confidence interval = 1.03, 1.19). These results corroborate the evidence that pesticides in vineyards contribute to mortality from brain cancer among farmers.
  [Viel, J.F., et al. 1998. Brain cancer mortality among French farmers: the vineyard pesticide hypothesis. Arch Environ Health 53(1):65-70]
• Correlation analysis of pesticide use data and cancer incidence rates in California counties.
  An ecological study in California analyzing a cancer registry and statewide pesticide use reporting system finds a correlation between Hispanic males diagnosed with brain cancer and atrazine.
  [Mills, P.K. 1998. Arch Environ Health 53(6):410-413]
• Glioma and occupational exposure in Sweden, a case-control study.
  The aim of the study was to analyse whether any job titles, industrial codes, and certain occupational exposures were associated with an increased risk of glioma. A population based case-control study of incident primary brain tumours in adults was carried out in Uppsala, Sweden in the period 1987-90. The study included 192 cases of glioma and 192 matched controls. It also included cases with other tumours of the central nervous system with matched controls. Information from all 343 controls was used in this study. Information was collected by means of a questionnaire that was sent to all subjects. An occupational hygienist reviewed the questionnaires for self reported exposures to substances and assessed whether these reported exposures were plausible or not in the corresponding occupation. The kappa coefficient for those classified by the two methods ranged between 0.46 and 0.88, and they were almost the same for cases and controls. For men exposed to solvents a relative risk (RR) of 2.6 (95% CI 1.3 to 5.2) was found. For men exposed to pesticides the RR was 1.8 (95% CI 0.6 to 5.1), and for plastic materials the RR was 3.6 (95% CI 1.0 to 12.4). For men employed in forestry and logging the RR was 2.2 (95% CI 0.9 to 5.3) and in basic metal industries 2.0 (95% CI 1.0 to 4.0). An increased risk of glioma was associated with use of solvents, pesticides, and plastic materials but this should be interpreted with some caution.
  [Rodvall, Y., et al. 1996. Occupational and Environmental Medicine 53:526-532]
• Proportionate mortality study of golf course superintendents.
  A proportionate mortality study of a cohort of 686 golf course superintendents finds an elevated number deaths from brain cancer (PMR 234), large intestine cancer (PMR 175), NHL (PMR 237), and prostate cancer (PMR 293).
  [Kross, B.C., et al. 1996. Am J Ind Med 29(5):501-506]
• Cancer mortality in a cohort of rural licensed pesticide users in the province of Rome.
  The mortality of a cohort of 2310 male workers who obtained a licence to handle pesticides in the period 1973-1979 in the province of Rome was investigated. The cohort contributed 26,846 person-years of exposure. The vital status of the cohort was determined up to the end of 1988. The causes of death of the 207 who had died were ascertained from death certificates. Standardized mortality ratios (SMR) were computed using both the provincial and the national mortality rates. The two methods yielded very similar results. Using the national rates, the SMR for all causes was 56 (95% confidence interval (CI) : 45.3-59.8), for cardiovascular diseases 47 (95% CI : 37.1-59.1), and for all cancers 72 (95% CI : 57.8-89.3). A statistically significant excess was noted for brain cancer (SMR = 270, 95% CI : 108.6-556.9). In addition, the cohort experienced statistically significant lower lung cancer mortality (SMR = 57, 95% CI : 35.6-80.0).
  [Figa-Talamanca, I. et al. 1993. Int J Epidemiol 22(4):579-583]
• Prevalence of glioblastoma multiforme subjects with prior herbicide exposure.
  A descriptive study of glioblastoma multiforme in Arkansas diagnosed patients finds a link to their occupational exposure to herbicides.
  [Smith-Rooker, J.L., et al. 1992. J neurosci Nurs 24(5):260-264]
• A case-control study of brain gliomas and occupational exposure to chemical carcinogens: the risk to farmers.
  A case control study shows an increased risk for brain gliomas for farmers who reported the use of pesticides and fertilizers (RR 1.6) with a significant increased risk for those that used insecticides and fungicides (RR 2.0).
  [Musicco, M., et al. 1988. American Journal of Epidemiology 128(4):778-785]
• Mortality among white and nonwhite farmers in North Carolina, 1976-1978.
  A mortality study of North Carolinian farmers finds that although there was no increased mortality for whites, nonwhite farmers have an increased frequency of leukemia (proportional mortality ratios (PMR) 1.9)
  [Delzell, E., and Grufferman, S. 1985. Am J Epidemiol 121(3):391-402]
• Lung cancer and other causes of death among licensed pesticide applicators.
  A cohort study of 3,827 white male licensed structural pest control workers in Florida finds excess of deaths for cancers of the brain.
  [Blair, A., et al. 1983. J Natl Cancer Inst 71(1):31-37]

Childhood Brain Cancer

• Exposure to pyrethroid pesticides and the risk of childhood brain tumors in East China
  Pesticide exposure is hypothesized as one of the risk factors for the development of childhood brain tumors (CBT). This hospital-based case-control study evaluated the association of pyrethroid pesticide exposure with the risk for CBT in a children population in East China. In total, 161 CBT cases and 170 controls were recruited from 2 children's medical centers in Shanghai (Xinhua Hospital and Shanghai Children's Medical Center) between September 2012 and June 2015. The cases and controls were matched for age, sex, and province of residence. Pyrethroid pesticide exposure was evaluated by urinalysis of 3 nonspecific metabolites of pyrethroids (cis-DCCA, trans-DCCA, and 3-PBA) using gas chromatography-mass spectrometry (GC-MS) detection and by administering a questionnaire. Unconditional logistic regression showed that trans-DCCA, 3-PBA, and total metabolites (sum of the 3 metabolites) were positively associated with the increased risk of CBT. Children in the highest quartile had a nearly 3-fold increased risk of CBT compared with those in the lowest quartile after adjusting for confounding factors (trans-DCCA, odds ratio (OR) = 2.58, 95% confidence interval (CI), 1.38-4.80, p = 0.003; 3-PBA, OR = 3.26, 95% CI, 1.73-6.14, p < 0.0001; total metabolites, OR = 3.60, 95% CI, 1.87-6.93, p < 0.0001). We also found that exposure to both mosquitocide and cockroach killer was related to the increased risk of CBT (mosquitocide, OR = 1.68, 95% CI, 1.06-2.67, p = 0.027; cockroach killer, OR = 1.83, 95% CI, 1.13-2.95, p = 0.013). These findings indicate that exposure to pyrethroid pesticides might be associated with increased risk of CBT. Prospective cohort studies with larger sample sizes are required to confirm this conclusion
  [Chen S, Gu S, Wang Y, Yao Y, et al. 2016. Environ Pollut. 218:1128-1134.]
• Increased risk of childhood brain tumors among children whose parents had farm-related pesticide exposures during pregnancy.
  Malignant brain tumors rank second in both incidence and mortality by cancer in children, and they are the leading cause of cancer death in children. While there are several studies which link pesticide exposure to increased risk of CBT, findings have been inconsistent. Authors performed a meta-analysis on 15 published epidemiological studies to test that in utero exposure to pesticides may be involved in the development of brain cancer in children. Findings of meta-analyses revealed a significantly increased risk of CBT among children whose mothers had farm-related exposures during pregnancy (RR=1.48, 95% CI=1.18-1.84). A dose response was recognized when this risk estimate was compared to those for risk of CBT from maternal exposure to non-agricultural pesticides (e.g., home extermination, pest strips) during pregnancy (RR=1.36, 1.10-1.68), and risk of CBT among children exposed to agricultural activities (RR=1.32, 1.04-1.67). Three studies combined for the paternal exposure to pesticides during preconception produced a calculated summary risk estimate of odds ratio (OR) = 2.29 (95% CI: 1.39-3.78). Meta-analysis of five studies of paternal exposure to pesticides during pregnancy produced a final calculated summary risk estimate of OR = 1.63 (95% CI: 1.16-2.31). The search of the CTD databases revealed association between herbicide and astrocytoma and more than 300 genes are altered by exposure to herbicide, fungicide, insecticide or pesticides. Based on the collective results of these meta-analyses, it appears that pesticide exposure may increase risk of CBT, with preconception and prenatal exposures being especially important factors in increasing risk of its development.
  [Kunkle B, Bae S, Singh KP, Roy D. 2014. JP J Biostat. 11(2):89-101]
• Exposure to pesticides and the risk of childhood brain tumors.
  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. Cases were recruited from 10 pediatric oncology centers, and controls by random-digit dialing, frequency matched on age, sex, and State of residence. 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. 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.
  [Greenop KR, Peters S, Bailey HD, et al. 2013. Cancer Causes Control. 24(7):1269-78]
• Childhood brain tumors, residential insecticide exposure, and pesticide metabolism genes
  Insecticides that target the nervous system may play a role in the development of childhood brain tumors (CBTs). Constitutive genetic variation affects metabolism of these chemicals. We analyzed population-based case-control data to examine whether CBT is associated with the functional genetic polymorphisms PON1C-108T, PON1Q192R, PON1L55M, BCHEA539T, FMO1C-9536A, FMO3E158K, ALDH3A1S134A, and GSTT1 (null). DNA was obtained from newborn screening archives for 201 cases and 285 controls, <or= 10 years of age, and born in California or Washington State between 1978 and 1990. Conception-to-diagnosis home insecticide treatment history was ascertained by interview. We observed no biologically plausible main effects for any of the metabolic polymorphisms with CBT risk. However, we observed strong interactions between genotype and insecticide exposure during childhood. Among exposed children, CBT risk increased per PON1-108T allele [odds ratio (OR) = 1.8; 95% confidence interval (CI), 1.1-3.0] and FMO1-9536A (*6) allele (OR = 2.7; 95% CI, 1.2-5.9), whereas among children never exposed, CBT risk was not increased (PON1: OR = 0.7; 95% CI, 0.5-1.0, interaction p = 0.005; FMO1: OR = 1.0; 95% CI, 0.6-1.6, interaction p = 0.009). We observed a similar but statistically nonsignificant interaction between childhood exposure and BCHEA539T (interaction p = 0.08). These interactions were present among both Hispanic and non-Hispanic white children. Based on known effects of these variants, these results suggest that exposure in childhood to organophosphorus and perhaps to carbamate insecticides in combination with a reduced ability to detoxify them may be associated with CBT. Confirmation in other studies is required.
  [Nielsen, S.S., et al. 2010. Childhood brain tumors, residential insecticide exposure, and pesticide metabolism genes. Environmental Health Perspectives 118(1):144-149]
• Critical Confluence: Gene Variants, Insecticide Exposure May Increase Childhood Brain Tumor Risk
  Epidemiologic data have suggested a link between pesticide exposures and childhood brain tumors. The link may be specific to insecticides such as organophosphorus and carbamate compounds, which are known to target the nervous system. Previously published work investigated the role of individual genetic variation with a focus on paraoxonase (PON1), a key enzyme in the metabolism of organophosphorus insecticides commonly used in homes at the time but now banned for residential use. This work showed that children with brain tumors were more likely to carry a common single-nucelotide polymorphism (SNP) gene variant in the promoter region of the PON1 gene (PON1C-108T) than other children, and that the association between this SNP and brain tumors was stronger in children with a history of home insecticide exposure. Research in an expanded study population now provides additional evidence that exposure to insecticides, paired with specific metabolism gene variants, may increase the risk of childhood brain tumors.
  [Barrett, J. 2010. Environ Health Perspect. 118(1): A35]
• Parental exposure to pesticides and childhood brain cancer: U.S. Atlantic coast childhood brain cancer study.
  The etiology of childhood brain cancer remains largely unknown. However, previous studies have yielded suggestive associations with parental pesticide use. Study aimed to evaluate parental exposure to pesticides at home and on the job in relation to the occurrence of brain cancer in children. Authors included 526 one-to-one-matched case-control pairs. Brain cancer cases were diagnosed at < 10 years of age, and were identified from statewide cancer registries of four U.S. Atlantic Coast states. Using information on residential pesticide use and jobs held by fathers during the 2-year period before the child's birth, authors assessed potential exposure to insecticides, herbicides, and fungicides. A significant risk of astrocytoma was associated with exposures to herbicides from residential use. Combining parental exposures to herbicides from both residential and occupational sources, the elevated risk remained significant. However, these findings should be viewed in light of limitations in exposure assessment and effective sample size.
  [Shim YK, Mlynarek SP, van Wijngaarden E. 2009.Environ Health Perspect. 117(6):1002-6.]
• A case-control study of childhood brain tumors and fathers' hobbies: a Children's Oncology Group study
  A case-control study evaluating parental risk factors for childhood brain tumors finds a significant association for home lawn care pesticide applications during pregnancy (OR 1.6) and after birth (OR 1.8) and thus pesticides may increase the risk of medulloblastoma and primitive neuroectodermal tumors in children.
  [Rosso, A.L., et al. 2008. Cancer Causes Control 19(10)1201-1207]
• The Upper Midwest Health Study: a case-control study of primary intracranial gliomas in farm and rural residents.
  A NIOSH population based case control study finds moving to a farm as an adolescent (between the ages of 11 and 20), rather than moving to a farm as an adult, is associated with a greater risk for gliomas.
  [Ruder, A.M., et al. 2006. J Agric Saf Health 12(4):255-274]
• Risk of brain tumors in children and susceptibility to organophosphorus insecticides: the potential role of paraoxonase (PON1).
  Prior research suggests that childhood brain tumors (CBTs) may be associated with exposure to pesticides. Organophosphorus insecticides (OPs) target the developing nervous system, and until recently, the most common residential insecticides were chlorpyrifos and diazinon, two OPs metabolized in the body through the cytochrome P450/paraoxonase 1 (PON1) pathway. To investigate whether two common PON1 polymorphisms, C-108T and Q192R, are associated with CBT occurrence, authors conducted a population-based study of 66 cases and 236 controls using DNA from neonatal screening archive specimens in Washington State, linked to interview data. The risk of CBT was nonsignificantly increased in relation to the inefficient PON1 promoter allele [per PON1(-108T) allele, relative to PON1(-108CC): odds ratio (OR) = 1.4; 95% confidence interval (CI), 1.0-2.2; p-value for trend = 0.07]. Notably, this association was strongest and statistically significant among children whose mothers reported chemical treatment of the home for pests during pregnancy or childhood (per PON1(-108T) allele: among exposed, OR = 2.6; 95% CI, 1.2-5.5; among unexposed, OR = 0.9; 95% CI, 0.5-1.6) and for primitive neuroectodermal tumors (per PON1(-108T) allele: OR = 2.4; 95% CI, 1.1-5.4). Larger studies that measure plasma PON1 levels and incorporate more accurate estimates of pesticide exposure will be required to confirm these observations.
  [Searles Nielsen S, Mueller BA, De Roos AJ, et al. 2005. Environ Health Perspect.113(7):909-13.]
• Farm-related exposures and childhood brain tumours in seven countries: results from the SEARCH International Brain Tumour Study.
  A total of 1218 cases of childhood brain tumours (CBT) and 2223 control subjects from the general population were included in a population-based case-control study conducted in nine centres in seven countries. Mothers were asked about farm- or agriculture-related exposures. Significantly elevated odds ratios (OR) for CBT were associated with children's personal and maternal prenatal exposure while living on a farm with pigs (child OR = 1.7, mother OR = 2.3), horses (child OR = 1.6, mother OR = 1.8), dogs (child OR = 1.5, mother OR = 1.5) and cats (child OR = 1.5, mother OR = 1.7). Children who were exposed to pigs, horses and cats combined, while living on a farm, had a threefold elevated OR for CBT. Increased ORs for primitive neuroectodermal tumours (PNET) were associated with children's farm exposure to dogs (OR = 1.9) and cats (OR = 2.2), and maternal farm exposure to pigs (OR = 4.2). The OR for CBT was elevated (OR = 2.3) for children of mothers who had preconception/prenatal farm- or agriculture-related employment involving potential contact with animals, relative to no farm- or agriculture-related employment. In particular, increased ORs for CBT were observed for children of mothers who were employed as general farmers (OR = 4.1) or general farm workers (OR = 3.8). During the 5 years preceding the index child's birth, maternal exposures were related to CBT, relative to no maternal exposure to agricultural chemicals or animal products: fertilisers (OR = 1.8), pesticides (OR = 2.0), animal manure (OR = 2.0) and unprocessed wool (OR = 3.0). Our findings suggest that various farm-related exposures are positively associated with CBT and warrant further investigation into the public health importance of these associations.
  [Efird, J.T., et al. 2003. Paediatr Perinat Epidemiol 17(2):201-211]
• Parental occupational exposure to pesticides and childhood brain cancer.
  A community-based case-control study of parental occupational pesticide exposure and childhood brain cancer finds a slightly elevated risk of astrocytoma for paternal exposure to insecticides, herbicides, and fungicides; a slightly elevated risk of primitive neuroectodermal tumors (PNET) for paternatal exposure to herbicides. The study also finds a small elevated risk for astrocytoma for maternal exposure to insecticides and non-agricultural fungicides.
  [Van Wijngaarden, E., et al. 2003. American Journal of Epidemiology 157(11):989-997]
• Farm and animal exposures and pediatric brain tumors: results from the United States West Coast Childhood Brain Tumor Study.
  Nineteen counties from San Francisco and Los Angeles, California and Seattle, Washington were the United States sites for a large population-based case-control study of childhood brain tumors (CBTs), sponsored by the National Cancer Institute. CBT patients who were < 20 years of age and were diagnosed between 1984 and 1991 were reported to each region's cancer registry. The 801 control subjects were obtained by random digit dial and were frequency-matched to the 540 CBT patients in San Francisco and Seattle (one patient to two controls) and in Los Angeles (one patient to one control). Data collected by in-person interview with subjects' mothers were analyzed to investigate an association between risk for CBTs and life on a farm, exposure to farm animals (dairy cattle, beef cattle, pigs, sheep/goats, poultry, and horses), and some cat and non-farm horse exposures. Elevated risks for CBTs were observed in association with mothers' exposure to pigs [odds ratio (OR) = 3.8, 95% confidence interval (CI) = 1.2-12] and horses (OR = 2.2, 95% CI = 1.0-4.8) on a farm during the index pregnancy. Children diagnosed with primitive neuroectodermal tumors showed elevated risks for CBTs with personal and maternal prenatal exposure to pigs (child, OR = 4.0, 95% CI = 1.2-13; mother, OR = 11.9, 95% CI = 2.8-51) and poultry (child, OR = 3.0, 95% CI = 1.1-8.0; mother, OR = 4.0, 95% CI = 1.2-14). No other animal exposures of children or mothers were found to be consistently related to CBTs. Children diagnosed with primitive neuroectodermal tumors who were on a farm for > 1 year and were first on a farm when they were < 6 months of age also had increased risk for CBTs (OR = 3.9, 95% CI = 1.2-13). A somewhat increased risk for CBTs was found for children of mothers who ever had worked on livestock farms compared with mothers who never had worked on a farm (OR = 7.4, 95% CI = 0.86-64, based on five case mothers and one control mother who worked on livestock farms during the 5 years preceding the birth of the index child). The associations are consistent with those of two previous studies in Norway (P. Kristensen et al., Int. J. Cancer, 65: 39-50, 1996) and the United States and Canada (G. R. Bunin et al., Cancer Epidemiol. Biomark. Prev., 3: 197-204, 1994) that investigated the role of farm-related exposures in the etiology of CBTs.
  [Holly, E.A., et al. 1998. Cancer Epidemiol Biomarkers Prev 7(9):797-802]
• Household pesticides and risk of pediatric brain tumors.
  A follow-up to a population-based case-control study of pediatric brain tumors in Los Angeles County, California, involving mothers of 224 cases and 218 controls, investigated the risk of household pesticide use from pregnancy to diagnosis. Risk was significantly elevated for prenatal exposure to flea/tick pesticides -odds ratio (OR) = 1.7; 95% confidence interval (CI), 1.1-2.6-, particularly among subjects less than 5 years old at diagnosis (OR = 2.5; CI, 1. 2-5.5). Prenatal risk was highest for mothers who prepared, applied, or cleaned up flea/tick products themselves (OR = 2.2; CI, 1.1-4.2; for subjects less than 5 years of age, OR = 5.4; CI, 1.3-22.3). A significant trend of increased risk with increased exposure was observed for number of pets treated (p = 0.04). Multivariate analysis of types of flea/tick products indicated that sprays/foggers were the only products significantly related to risk (OR =10.8; CI, 1.3-89.1). Elevated risks were not observed for termite or lice treatments, pesticides for nuisance pests, or yard and garden insecticides, herbicides, fungicides, or snail killer. Certain precautions,if ignored, were associated with significant increased risk: evacuating the house after spraying or dusting for pests (OR = 1.6; CI, 1.0-2.6), delaying the harvest of food after pesticide treatment (OR = 3.6; CI, 1.0-13.7), and following instructions on pesticide labels (OR = 3. 7;CI, 1.5-9.6). These findings indicate that chemicals used in flea/tick products may increase risk of pediatric brain tumors and suggest that further research be done to pinpoint specific chemicals involved.
  [Pogoda, J.M. and Preston-Martin, S. 1997. Environmental Health Perspectives 105:1214-1220]
• Cancer in offspring of parents engaged in agricultural activities in Norway: incidence and risk factors in the farm environment.
  In this study of cancer in offspring we demonstrate that factors linked to horticulture and use of pesticides are associated with cancer at an early age, whereas factors in animal husbandry, in particular poultry farming, are associated with cancers in later childhood and young adulthood. Incident cancer was investigated in offspring born in 1952-1991 to parents identified as farm holders in agricultural censuses in Norway in 1969-1989. In the follow-up of 323,292 offspring for 5.7 million person-years, 1,275 incident cancers were identified in the Cancer Registry for 1965-1991. The standardized incidence for all cancers was equal to the total rural population of Norway, but cohort subjects had an excess incidence of nervous-system tumours and testicular cancers in certain regions and strata of time that could imply that specific risk factors were of importance. Classification of exposure indicators was based on information given at the agricultural censuses. Risk factors were found for brain tumours, in particular non-astrocytic neuroepithelial tumours: for all ages, pig farming tripled the risk [rate ratio (RR), 3.11; 95% confidence interval (CI), 1.89-5.13]; indicators of pesticide use had an independent effect of the same magnitude in a dose-response fashion, strongest in children aged 0 to 14 years (RR, 3.37; 95% CI, 1.63-6.94). Horticulture and pesticide indicators were associated with all cancers at ages 0 to 4 years, Wilms' tumour, non-Hodgkin's lymphoma, eye cancer and neuroblastoma. Chicken farming was associated with some common cancers of adolescence, and was strongest for osteosarcoma and mixed cellular type of Hodgkin's disease. The main problem in this large cohort study is the crude exposure indicators available; the resulting misclassification is likely to bias any true association towards unity.
  [Kristensen, P., et al. 1996. Int J Cancer 65(1):39-50]
• Incidence and risk factors for childhood brain tumors in the Ile de France.
  A case-control study investigating risk factors for childhood brain tumors was conducted in the Ile de France (Paris region). During a 2-year period (1985-1987) 109 newly diagnosed cases were identified and, of these, 75 could be interviewed. In the same region, 113 population controls, frequency-matched for year of birth, were interviewed. Odds ratios adjusted for child's age and sex and for maternal age were estimated for each risk factor present in utero or during childhood by conditional logistic regression. Statistically significant associations were found for the following risk factors: farm residence, cat scratches, home treated with pesticides, passive smoking, family history of cancer, antihistamine intake. Intake of vitamin supplements during childhood was associated with a decrease in risk. This study is part of a multicentric case-control study coordinated by the International Agency for Research on Cancer and its results will be compared for consistency, and pooled with those of other centers using the same protocol.
  [Cordier, S., et al. 1994. Int J Cancer 59(6):776-782]
• Risk factors for astrocytic glioma and primitive neuroectodermal tumor of the brain in young children: a report from the Children's Cancer Group
  A case-control study focusing on gestational exposures find elevated risks for primitive neuroectodermal tumor (PNET), one the of the most common subtypes of brain tumors in children, for mother’s residence on a farm during pregnancy and for the child’s residence on a farm for at least one year. Mothers of astrocytoma brain cancer cases were more likely than their controls to report weekly use of insect sprays and pesticides.
  [Bunin, G.R., et al. 1994. Cancer Epidemiology, Biomarkers and Prevention 3:197-204]
• Family pesticide use and childhood brain cancer.
  The relationship between family pesticide use and childhood brain cancer was examined in a case-control study. Telephone interviews were conducted from June 1989 through March 1990 with the natural mothers of 45 childhood brain cancer cases, 85 friend controls, and 108 cancer controls. In comparisons to friend controls, significant positive associations were observed for use of pesticides to control nuisance pests in the home, no-pest-strips in the home, pesticides to control termites, Kwell shampoo, flea collars on pets, diazinon in the garden or orchard, and herbicides to control weeds in the yard. In comparisons to cancer controls, significant positive associations were observed for use of pesticide bombs in the home, pesticides to control termites, flea collars on pets, insecticides in the garden or orchard, carbaryl in the garden or orchard, and herbicides to control weeds in the yard. In general, positive associations in comparisons to one control group were supported by elevated odds ratios in comparisons to the other control group. Several potentially important associations were identified in this study. However, small sample sizes, potential recall bias, multiple comparisons, and lack of detailed exposure verification require further research to confirm these findings.
  [Davis, J., et al. 1993. Family pesticide use and childhood brain cancer. Archives of Environmental Contamination and Toxicology 24:87-92]
• Parental occupation and intracranial neoplasms of childhood: results of a case-control interview study.
  A case-control study of childhood brain tumors finds paternal employment in agriculture is associated with excess risk.
  [Wilkins, J.R. and T. Sinks. 1990. Am J Epidemiol 132(2):275-292]
• Paternal occupation and brain cancer in offspring: a mortality-based case-control study
  A mortality-based case-control study of Ohio-born children who died from brain cancer looking at paternal occupation finds that case fathers are more likely than control fathers to have been employed, at the time of the child’s birth, in agriculture.
  [Wilkins, J.R. and Koutras, R.A. 1988. Am J Ind Med 14(3):299-318]
• Risk factors for brain tumors in children
  An exploratory case-control study in Baltimore, Maryland finds that more children with brain tumors and children with other cancers are found to have been exposed to insecticides than other children.
  [Gold, E., et al. 1979. American Journal of Epidemiology 109(3):309-319]