SPHERL- Key findings from the 8-year longitudinal workplace
epidemiology study in lead workers
Agenda for
25-27 June
2025
Cris Williams
Senior Scientist Health, International Lead Association, United States
The ILA-sponsored Study for the Promotion of Health in Recycling Lead, or SPHERL, is the most up-to-date and scientifically robust prospective, longitudinal study of lead exposure on cardiovascular, neurological, and renal effects in workers.
Prior to SPHERL, health effects from occupational lead exposure were ascertained from cross-sectional studies that suffered from inadequate control of the many influences that confound study results such as uncertainties in lead exposure history, the timing of lead exposure relative to the onset of associated effects, as well as age, sex, BMI, and various other lifestyle factors.
A total of 18 peer reviewed studies were published in the scientific literature from the results of SPHERL, and the studies showed that blood lead increases from an average of 5 µg/dL at baseline to an average of 17 to 18 µg/dL (and up to 32 µg/dL) at follow up were without measurable effects on blood pressure, renal function, heart rate and heart rate variability (a function of autonomic nervous system function), peripheral nerve conduction velocity, and neurocognitive function.
The occupational cohort established in SPHERL has also served as the basis for a recent ILA-sponsored study of and publication on air Pb:blood Pb relationship, as well as a planned study on non-respiratory exposures to lead in the workplace.
Prior to SPHERL, health effects from occupational lead exposure were ascertained from cross-sectional studies that suffered from inadequate control of the many influences that confound study results such as uncertainties in lead exposure history, the timing of lead exposure relative to the onset of associated effects, as well as age, sex, BMI, and various other lifestyle factors.
A total of 18 peer reviewed studies were published in the scientific literature from the results of SPHERL, and the studies showed that blood lead increases from an average of 5 µg/dL at baseline to an average of 17 to 18 µg/dL (and up to 32 µg/dL) at follow up were without measurable effects on blood pressure, renal function, heart rate and heart rate variability (a function of autonomic nervous system function), peripheral nerve conduction velocity, and neurocognitive function.
The occupational cohort established in SPHERL has also served as the basis for a recent ILA-sponsored study of and publication on air Pb:blood Pb relationship, as well as a planned study on non-respiratory exposures to lead in the workplace.
Bio
Cris Williams is Senior Scientist – Health at ILA. He has more than 30 years’ experience in subjects including exposure assessment and occupational health. He is a member of the Society of Toxicology and the author or co-author of more than 30 peer-reviewed publications. Dr WIlliams holds a PhD in environmental toxicology from the University of Wisconsin-Madison.
