Tracing the long-term legacy of childhood lead exposure: a review of three decades of the port Pirie cohort study

Amelia K Searle; Peter A Baghurst; Miranda van Hooff; Michael G Sawyer; Malcolm R Sim; Cherrie Galletly; Levina S Clark; Alexander C McFarlane

doi:10.1016/j.neuro.2014.04.004

Tracing the long-term legacy of childhood lead exposure: a review of three decades of the port Pirie cohort study

Neurotoxicology. 2014 Jul:43:46-56. doi: 10.1016/j.neuro.2014.04.004. Epub 2014 Apr 28.

Authors

Amelia K Searle¹, Peter A Baghurst², Miranda van Hooff³, Michael G Sawyer⁴, Malcolm R Sim⁵, Cherrie Galletly⁶, Levina S Clark⁷, Alexander C McFarlane³

Affiliations

¹ Centre for Traumatic Stress Studies, School of Population Health, University of Adelaide, South Australia 5000, Australia. Electronic address: amelia.searle@adelaide.edu.au.
² Discipline of Public Health, University of Adelaide, South Australia 5000, Australia; Discipline of Paediatrics, University of Adelaide, South Australia 5000, Australia.
³ Centre for Traumatic Stress Studies, School of Population Health, University of Adelaide, South Australia 5000, Australia.
⁴ Discipline of Paediatrics, University of Adelaide, South Australia 5000, Australia; Research and Evaluation Unit, Women's and Children's Health Network, South Australia 5000, Australia.
⁵ Department of Epidemiology & Preventive Medicine, Monash University, Victoria 3004, Australia.
⁶ Discipline of Psychiatry, University of Adelaide, South Australia 5000, Australia.
⁷ Psychology Clinic, Flinders University, South Australia 5000, Australia.

PMID: 24785378
DOI: 10.1016/j.neuro.2014.04.004

Abstract

Several prospective cohort studies have demonstrated that childhood lead levels show small but statistically significant adjusted associations with subsequent development in later childhood and adolescence. The Port Pirie Cohort study is one of the few prospective cohort studies to follow participants into adulthood. This paper reviews all childhood and adulthood findings of the Port Pirie Cohort study to date. Cohort members (initially, 723 infants born in/around the lead-smelting town of Port Pirie) showed a wide range of childhood blood lead levels, which peaked around 2 years old (M=21.3μg/dL, SD=1.2). At all childhood assessments, postnatal lead levels - particularly those reflecting cumulative exposure - showed small significant associations with outcomes including cognitive development, IQ, and mental health problems. While associations were substantially attenuated after adjusting for several childhood covariates, many remained statistically significant. Furthermore, average childhood blood lead showed small significant associations with some adult mental health problems for females, including anxiety problems and phobia, though associations only approached significance following covariate adjustment. Overall, there did not appear to be any age of greatest vulnerability or threshold of effect, and at all ages, females appeared more susceptible to lead-associated deficits. Together, these findings suggest that the associations between early childhood lead exposure and subsequent developmental outcomes may persist. However, as the magnitude of these effects was small, they are not discernible at the individual level, posing more of a population health concern. It appears that the combination of multiple early childhood factors best predicts later development. As such, minimising lead exposure in combination with improving other important early childhood factors such as parent-child interactions may be the best way to improve developmental outcomes.

Keywords: Childhood; Low-level lead exposure; Port Pirie Cohort study; Prospective; Review.

MeSH terms

Child, Preschool
Cohort Studies
Developmental Disabilities / chemically induced*
Environmental Exposure*
Female
Humans
Lead / blood
Lead Poisoning / blood
Lead Poisoning / epidemiology*
Lead Poisoning / etiology*
Male
Parent-Child Relations

Substances

Lead