INTRODUCTIONSeveral studies have suggested that blood lead and cadmium levels that are well below the current safety standards are associated with health risks, such as peripheral arterial disease, impaired renal function and elevated blood pressure.(1-3) Menke et al reported that blood lead level was significantly associated with myocardial infarction and stroke mortality, even when it was below 0.48 μmol/L (10 μg/dL).(4) A Taiwanese study by Huang reported that seafood contamination was very common in Taiwan, and that the lead and copper levels of the rivers in Taiwan were the highest in the world.(5) The abstract of a study that investigated the concentration of heavy metals in the hair of 700 residents in Taiwan reported that most of the residents exhibited elevated heavy metal levels.(6) However, this abstract is unpublished and only found on the Internet.(6) To the best of our knowledge, there has been no formal report describing the heavy metal levels of healthy subjects in Taiwan. The two reports (5,6) indicate that the finding of elevated heavy metal levels in Taiwanese people might not be unusual. Therefore, for the present study, we hypothesised that there may be greater levels of four common heavy metals (lead, mercury, arsenic and cadmium) in the blood of a Southern Taiwanese population than in Western populations.The most reliable methods for measuring body lead burden are bone X-ray fluorescence studies and calcium disodium ethylenediaminetetraacetic acid (CaNa 2 EDTA) mobilisation tests. This is because blood lead levels only reflect recent exposure to lead (7) and not the lead burden of the body. According to recent reports, body lead burden can be measured by collecting 72-hour urinary lead excretion after intravenous infusion of 1 g of CaNa 2 EDTA.(8,9) These reports recommend the daily collection of urine for 72 hours in a high-volume container before the urine is sent for lead measurement. If most of the lead (or other heavy metal) can be excreted during the first 24 hours after CaNa 2 EDTA infusion, then the level of heavy metal in the urine during the first 24 hours may be reflective of the body burden of these heavy metals. We hypothesised that the level of heavy metal in the urine collected in the first 24 hours would be positively correlated with the body burden of the heavy metal. Thus, the aim of the present study was twofold. First, we aimed to assess the levels of four common heavy metals (lead, mercury, arsenic and cadmium) in the blood of apparently healthy Taiwanese adults and to determine whether these heavy metal levels are greater than those of adults from Western countries. Second, we aimed to test our hypothesis that the level of heavy metal in first-day urine is reflective of the body burden of heavy metals (i.e. most heavy metals are excreted during the first 24 hours). METHODSA total of 40 apparently healthy persons (34 men, six women)