Table 3

Comparison of occupational exposure assessment sources

Assessment sourcesBirth certificatesInterviewCompany recordsRegisters
AdvantageEase of access and low cost
 Less recall bias
 The recorded paternal occupation seems more reliable than maternal occupationDetailed information about occupational exposure can be acquired in standard way
 Confounder information may be availableNot subject to recall bias and tend to be more complete in recording occupational exposureEase of assess and low cost
 Less recall bias
 The recorded paternal occupation seems more reliable than maternal occupation
 Investigator can get the outcome information at any time
DisadvantageIncompleteness
 Limited to the title of occupation, information bias is more likely
 Job changing may introduce the possibility of misclassification of exposure status
 Limited confounder information related to congenital malformationExpensive and time consuming
 Certainty depends on the education level and professional knowledge
 Easy to contact effect
 Interview of the spouse may not provide valid and complete information
 Information bias is more likelyMay lack the updating information about changing of exposure status over time for individual or certain job title
 The completeness and validity of data obtained may be not available
 Information of potential confounders may be insufficientConfounding information may be scanty
 Problem of miscoding and wrong data entry may exist