Morning spot urine samples were collected in polypropylene tubes, frozen within 1 to 2 h of collection, shipped buried in dry ice, and stored at −70°C in the Penn Medical Laboratory, MedStar Research Institute, Washington, DC, USA. In 2009, urine samples were shipped to the Trace Metals Laboratory at Graz University, Austria, to measure Cd and other metals using inductively coupled plasma–mass spectrometry (ICP-MS) (Agilent 7700x ICP–MS; Agilent Technologies). The limit of detection (LOD) for urine Cd was 0.015μg/L . In one participant below the LOD, the Cd concentration was imputed as the LOD divided by the square root of two. Urine Cd concentrations were corrected for molybdenum oxide interference. Other laboratory details and extensive quality control/quality assurance have been published (Scheer et al. 2012 (link)). To account for urine dilution, urine Cd concentrations were expressed in micrograms per gram of urine creatinine. Urine creatinine was measured at the Laboratory of the National Institute of Diabetes and Digestive and Kidney Disease, Epidemiology and Clinical Research Branch (Phoenix, Arizona, USA) by an alkaline picrate rate method.