title: Study for Promotion of Health in Recycling Lead - Rationale and design.
abstract: BACKGROUND
  The level at which low-level lead exposure produces subclinical adverse health effects in adults remains to be established.
  
  
  METHODS
  The Study for Promotion of Health in Recycling Lead (SPHERL) will enroll 500 newly hired workers, whose blood lead during 2 years of follow-up is expected to increase from levels less than 2 μg/dl, as currently observed in the US population, to 20-30 μg/dl. The main outcome variables to be studied are (i) blood pressure (BP) analyzed as a continuous or categorical variable, both cross-sectionally and longitudinally, and using conventional and ambulatory BP measurement; (ii) indexes of glomerular and tubular renal function, (iii) heart rate variability analyzed in the frequency domain as measure of autonomous sympathetic modulation, (iv) peripheral nerve conductivity velocity, (v) neurocognitive performance, and (vi) quality of life. Expected outcomes. Assuming a 10-fold increase in blood lead, SPHERL will have sufficient statistical power to detect over 2 years a steepening of the age-related rise in systolic BP from 1 to 5 mmHg and a doubling of the age-related decline in the estimated glomerular filtration rate from 3.5 to 7.0 ml/min/1.73 m(2). The longitudinal design of our study complies with the temporality principle of the Bradford-Hill criteria for assessing possible causality between outcomes and exposure. SPHERL will attempt to resolve the apparent contradiction between general population studies showing associations between adverse health effects and low lead exposure with blood lead levels below 5 μg/dl and studies conducted in occupational cohorts indicating that adverse effects of lead exposure occur at much higher blood lead levels.
authors.affiliation: Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven , Leuven , Belgium.
authors.forename: Azusa
authors.initials: A
authors.lastname: Hara
authors.forename: Yu-Mei
authors.initials: YM
authors.lastname: Gu
authors.forename: Thibault
authors.initials: T
authors.lastname: Petit
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Liu
authors.forename: Lotte
authors.initials: L
authors.lastname: Jacobs
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Zhang
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Yang
authors.forename: Yu
authors.initials: Y
authors.lastname: Jin
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Thijs
authors.forename: Fang-Fei
authors.initials: FF
authors.lastname: Wei
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
authors.forename: Jan A
authors.initials: JA
authors.lastname: Staessen
mesh_terms: D000328:Adult; D001794:Blood Pressure; D003071:Cognition; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007854:Lead / Q000009:adverse effects*; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D011446:Prospective Studies; D059027:Recycling
chemical_list: D007854:Lead
keywords: Autonomic nervous function; blood pressure; cardiovascular regulation; lead; occupational exposure; renal function