Epidemiologic study of neural tube defects in Los Angeles County. II. Etiologic factors in an area with low prevalence at birth

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Teratology; (United States)

DOI:https://doi.org/10.1002/tera.1420250309· OSTI ID:6706802

Sever, L E

Epidemiologic characteristics of neural tube defect (NTD) births occurring in Los Angeles County, California, residents during the period 1966-1972 are presented. The prevalence at birth was 0.52/1000 births for anencephalus, 0.51/1000 for spina bifida, and 0.08/1000 for encephalocele, rates considered to be low for a predominantly white population. We hypothesized that environmental (nongenetic) factors are of less etiologic importance in a low-prevalence population than in areas or time periods with high prevalence. We tested that hypothesis by examining epidemiologic characteristics of NTDs in Los Angeles County and comparing them with high-prevalence populations. The data did not support a major etiologic role for environmental factors: (1) no significant differences between rates by month of birth or conception; (2) no significant association with maternal age or parity for anencephalus; for spina bifida a significant maternal age effect (P < 0.01) and for encephalocele a parity effect (P < 0.02); and (3) no significant relationship with father's occupational class for either anencephalus or encephalocele but a marginally significant (P < 0.05) inverse association for spina bifida when a statistic based on ordinal relationships was used. Findings supporting the importance of genetic factors in etiology included: (1) a high percentage of males; (2) a higher twin concordance rate than in high-prevalence populations; and (3) an anencephalus rate among blacks comparable with rates for blacks in other United States populations. Our findings in conjunction with those from other areas and times of low prevalence suggest environmental factors play a relatively insignificant role in the etiology of NTDs in such populations.

• Research Organization: Pacific Northwest Lab., Richland, WA
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6706802
• Journal Information: Teratology; (United States), Journal Name: Teratology; (United States) Vol. 25; ISSN TJADA
• Country of Publication: United States
• Language: English

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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
99 GENERAL AND MISCELLANEOUS
BODY
BRAIN
CALIFORNIA
CENTRAL NERVOUS SYSTEM
CONGENITAL MALFORMATIONS
DATA
DATA COMPILATION
EPIDEMIOLOGY
ETIOLOGY
FEDERAL REGION IX
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HUMAN POPULATIONS
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LOS ANGELES
MALFORMATIONS
MORTALITY
NEONATES
NERVOUS SYSTEM
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NUMERICAL DATA
ORGANS
PARTURITION
PATHOLOGICAL CHANGES
POLLUTANTS
POPULATIONS
SEX DEPENDENCE
TERATOGENESIS
URBAN AREAS
USA