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Geographic risk modeling of childhood cancer relative to county-level crops, hazardous air pollutants and population density characteristics in Texas.

Thompson JA, Carozza SE, Zhu L - Environ Health (2008)

Bottom Line: The risk for Hodgkin lymphoma appeared to be reduced in areas of rapidly growing population.The current study identified geographic factors supporting more focused studies of germ cell tumors and "other" gliomas in areas of intense cropping, hepatic cancer near Hazardous Air Pollutant (HAP) release facilities and specific locations with increased risks for CNS embryonal tumors and for "other" leukemias.Further study should be performed to evaluate potentially lower risk for Hodgkin lymphoma and malignant bone tumors in counties with rapidly growing population.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Large Animal Clinical Science, Texas A&M University, College Station, Texas 77843-4475, USA. jthompson@cvm.tamu.edu

ABSTRACT

Background: Childhood cancer has been linked to a variety of environmental factors, including agricultural activities, industrial pollutants and population mixing, but etiologic studies have often been inconclusive or inconsistent when considering specific cancer types. More specific exposure assessments are needed. It would be helpful to optimize future studies to incorporate knowledge of high-risk locations or geographic risk patterns. The objective of this study was to evaluate potential geographic risk patterns in Texas accounting for the possibility that multiple cancers may have similar geographic risks patterns.

Methods: A spatio-temporal risk modeling approach was used, whereby 19 childhood cancer types were modeled as potentially correlated within county-years. The standard morbidity ratios were modeled as functions of intensive crop production, intensive release of hazardous air pollutants, population density, and rapid population growth.

Results: There was supportive evidence for elevated risks for germ cell tumors and "other" gliomas in areas of intense cropping and for hepatic tumors in areas of intense release of hazardous air pollutants. The risk for Hodgkin lymphoma appeared to be reduced in areas of rapidly growing population. Elevated spatial risks included four cancer histotypes, "other" leukemias, Central Nervous System (CNS) embryonal tumors, CNS other gliomas and hepatic tumors with greater than 95% likelihood of elevated risks in at least one county.

Conclusion: The Bayesian implementation of the Multivariate Conditional Autoregressive model provided a flexible approach to the spatial modeling of multiple childhood cancer histotypes. The current study identified geographic factors supporting more focused studies of germ cell tumors and "other" gliomas in areas of intense cropping, hepatic cancer near Hazardous Air Pollutant (HAP) release facilities and specific locations with increased risks for CNS embryonal tumors and for "other" leukemias. Further study should be performed to evaluate potentially lower risk for Hodgkin lymphoma and malignant bone tumors in counties with rapidly growing population.

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Frequency distribution of county-year cropping intensity for total corn, sorghum, wheat and cotton.
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Figure 3: Frequency distribution of county-year cropping intensity for total corn, sorghum, wheat and cotton.

Mentions: Two hundred and fifty four counties were modeled for 13 years providing 3302 county-years. The majority of county-years (79.1%) were classified as rural with a population of less than 50,000. For each year of the study there were exactly 4 metropolitan counties having more than one million residents: Bexar, Dallas, Harris and Tarrant counties. Population growth varied widely with population losses of more than 1% to population growth of greater than 4% both common. Growth of greater than 1% occurred in 41.7% of the county-years (Figure 1). The amount of HAP-release was commonly less than 50 tonnes per county-year but some very high releases were recorded, with 15.8% of the county-years having greater than 100 tonnes of release (Figure 2). Most county-years had less than 10% of the county area planted in corn, sorghum, cotton and wheat; however some county-years had greater than 50%, with 20.1% of the county-years having greater than 20% of the county cropped with these four crops (Figure 3).


Geographic risk modeling of childhood cancer relative to county-level crops, hazardous air pollutants and population density characteristics in Texas.

Thompson JA, Carozza SE, Zhu L - Environ Health (2008)

Frequency distribution of county-year cropping intensity for total corn, sorghum, wheat and cotton.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2572154&req=5

Figure 3: Frequency distribution of county-year cropping intensity for total corn, sorghum, wheat and cotton.
Mentions: Two hundred and fifty four counties were modeled for 13 years providing 3302 county-years. The majority of county-years (79.1%) were classified as rural with a population of less than 50,000. For each year of the study there were exactly 4 metropolitan counties having more than one million residents: Bexar, Dallas, Harris and Tarrant counties. Population growth varied widely with population losses of more than 1% to population growth of greater than 4% both common. Growth of greater than 1% occurred in 41.7% of the county-years (Figure 1). The amount of HAP-release was commonly less than 50 tonnes per county-year but some very high releases were recorded, with 15.8% of the county-years having greater than 100 tonnes of release (Figure 2). Most county-years had less than 10% of the county area planted in corn, sorghum, cotton and wheat; however some county-years had greater than 50%, with 20.1% of the county-years having greater than 20% of the county cropped with these four crops (Figure 3).

Bottom Line: The risk for Hodgkin lymphoma appeared to be reduced in areas of rapidly growing population.The current study identified geographic factors supporting more focused studies of germ cell tumors and "other" gliomas in areas of intense cropping, hepatic cancer near Hazardous Air Pollutant (HAP) release facilities and specific locations with increased risks for CNS embryonal tumors and for "other" leukemias.Further study should be performed to evaluate potentially lower risk for Hodgkin lymphoma and malignant bone tumors in counties with rapidly growing population.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Large Animal Clinical Science, Texas A&M University, College Station, Texas 77843-4475, USA. jthompson@cvm.tamu.edu

ABSTRACT

Background: Childhood cancer has been linked to a variety of environmental factors, including agricultural activities, industrial pollutants and population mixing, but etiologic studies have often been inconclusive or inconsistent when considering specific cancer types. More specific exposure assessments are needed. It would be helpful to optimize future studies to incorporate knowledge of high-risk locations or geographic risk patterns. The objective of this study was to evaluate potential geographic risk patterns in Texas accounting for the possibility that multiple cancers may have similar geographic risks patterns.

Methods: A spatio-temporal risk modeling approach was used, whereby 19 childhood cancer types were modeled as potentially correlated within county-years. The standard morbidity ratios were modeled as functions of intensive crop production, intensive release of hazardous air pollutants, population density, and rapid population growth.

Results: There was supportive evidence for elevated risks for germ cell tumors and "other" gliomas in areas of intense cropping and for hepatic tumors in areas of intense release of hazardous air pollutants. The risk for Hodgkin lymphoma appeared to be reduced in areas of rapidly growing population. Elevated spatial risks included four cancer histotypes, "other" leukemias, Central Nervous System (CNS) embryonal tumors, CNS other gliomas and hepatic tumors with greater than 95% likelihood of elevated risks in at least one county.

Conclusion: The Bayesian implementation of the Multivariate Conditional Autoregressive model provided a flexible approach to the spatial modeling of multiple childhood cancer histotypes. The current study identified geographic factors supporting more focused studies of germ cell tumors and "other" gliomas in areas of intense cropping, hepatic cancer near Hazardous Air Pollutant (HAP) release facilities and specific locations with increased risks for CNS embryonal tumors and for "other" leukemias. Further study should be performed to evaluate potentially lower risk for Hodgkin lymphoma and malignant bone tumors in counties with rapidly growing population.

Show MeSH
Related in: MedlinePlus