BackgroundEnvironmental lead exposure has long been implicated in neurodegenerative disease. In Australia, population lead burdens rose steeply during the 20th century due to widespread use of leaded petrol, followed by a sharp decline after its phase-out in 2002. Prior ecological studies (Laidlaw et al., 2015; Zahran et al., 2017) proposed that motor neurone disease (MND) mortality follows cumulative lead exposure with an approximate 20-year latency, reflecting delayed toxic release from skeletal stores.
ObjectivesThis study re-examines the temporal relationship between national petrol-lead emissions and MND mortality in Australia using updated official mortality data (1986-2022) and the Kristensen (1958-2002) emissions inventory.
MethodsAge-standardised MND mortality rates from the Australian Institute of Health and Welfare were correlated with cumulative petrol-lead emissions under varying time-lag scenarios (0-30 years). Ordinary least squares regression models were fitted to identify the lag yielding the strongest association. A projection of MND mortality to 2035 was then generated using the optimal lag model, assuming constant cumulative lead exposure post-2002.
ResultsThe best-fit model occurred at a 20-year lag (R2 = 0.72, p = 1.9 x 10-5), consistent with Laidlaws estimated latency. The model indicates that MND mortality rises approximately two decades after peak cumulative petrol-lead exposure and subsequently stabilises and declines as high-exposure cohorts age out. Projections to 2035 show a gradual downward trend in national MND mortality following the 2002 lead phase-out.
ConclusionsThese findings corroborate earlier hypotheses linking lead exposure to MND mortality and provide quantitative evidence of a {approx} 20-year temporal lag between population-level lead accumulation and neurodegenerative outcomes. The biological plausibility of this delay aligns with the long half-life of skeletal lead and its role in oxidative neuronal injury. Persistent lead contamination therefore remains a continuing public-health concern with potential implications for adult neurodegenerative disease prevention.