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Toxicological information

Exposure related observations in humans: other data

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Administrative data

Endpoint:
exposure-related observations in humans: other data
Type of information:
other: Prospective cohort study - mortality
Adequacy of study:
supporting study

Data source

Reference
Reference Type:
publication
Title:
Low childhood IQ and early adult mortality: the role of explanatory factors in the 1958 British Birth Cohort
Author:
Jokela M, Batty GD, Deary IJ, Gale CR & Kivimaki, M
Bibliographic source:
Pediatrics. 124(3): e380-e388

Materials and methods

Type of study / information:
This study examined whether the association between childhood IQ and later mortality risk was explained by early developmental advantages or mediated by adult sociodemographic factors and health behaviors. Although not about lead, the potential relevance of this study to lead research is that lead exposure is a risk factor for IQ decrements and thus the relationship between childhood IQ and adult mortality is of interest.
Endpoint addressed:
not applicable
Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Prospective cohort study

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Ethical approval:
confirmed and informed consent free of coercion received

Results and discussion

Results:
Of 10,620 participants from the 1958 British Birth Cohort Study whose IQ was assessed at age 11 and who were followed up to age 46, 192 died between the ages of 23 and 46. Higher childhood IQ was related to lower mortality risk (OR = 0.80, 95% confidence interval: 0.69-0.93). Adjusting for parents' interest in child's education attenuated the IQ-mortality association by 15 to 20% and adult education and psychosomatic symptoms both attenuated the association by 25%. Other factors, such as birth weight, childhood height, father’s occupational class, family size, and family difficulties, as well as adult occupational class, marital status, smoking, BMI, and alcohol use, were less influential.

Applicant's summary and conclusion

Conclusions:
The authors conclude, "In a cohort of British men and women, the most important explanatory factors for the lower mortality rate among individuals with high IQ were parental interest in child’s education, high adult educational level, and low prevalence of psychosomatic symptoms. However, common sociodemographic risk factors and health behaviors may not be sufficient to explain the association between IQ and early mortality completely."
Executive summary:

This cohort study examined whether the association between childhood IQ and later mortality risk was explained by early developmental advantages or mediated by adult sociodemographic factors and health behaviors. Although not about lead, the potential relevance of this study to lead research is that lead exposure is a risk factor for IQ decrements and thus the relationship between childhood IQ and adult mortality is of interest. Of 10,620 participants from the 1958 British Birth Cohort Study whose IQ was assessed at age 11 and who followed up to age 46, 192 died between the ages of 23 and 46. Higher childhood IQ was related to lower mortality risk (OR = 0.80, 95% confidence interval: 0.69-0.93). Adjusting for parents' interest in child's education attenuated the IQ-mortality association by 15 to 20%, and adult education and psychosomatic symptoms both attenuated the association by 25%. Other covariates were less influential. The authors conclude, "In a cohort of British men and women, the most important explanatory factors for the lower mortality rate among individuals with high IQ were parental interest in child’s education, high adult educational level, and low prevalence of psychosomatic symptoms. However, common sociodemographic risk factors and health behaviors may not be sufficient to explain the association between IQ and early mortality completely."