LAUSR

Dear Sir, We read the article by Averina et al about investigating environmental pollutants in Norwegian blood donors with great interest. Blood transfusion is a very common procedure in neonatology practice, especially in preterm infants. Although many risks and complications are well known, heavy metal and toxin overloads are underestimated hazardous effects of this procedure. The authors clearly demonstrated that a remarkable number of Norwegian donors have whole-blood mercury and lead concentrations above the reference doses. Several regulatory agencies such as the Agency for Toxic Substances and Disease Registry, Joint FAO/WHO Expert Committee on Food Additives, Food and Agriculture Organization of the United Nations, Environmental Protection Agency (EPA) and World Health Organization are working to ensure the adequate margin of heavy metal intake. They estimate different safe values depending on considered studies. Because tolerable doses of intravenous lead and mercury are unknown, the authors set a lower threshold, that is, 0.36 μ/kg dose of lead, based on previous studies. Daily maximum permissible intravenous mercury was calculated as 0.095 μ/kg, which is not likely to cause harmful effects as determined by the EPA. Mercury and lead concentrations were higher than the upper limits for preterm infants in 10.5% and 17.9% of the donors' blood, respectively, based on these estimations. We have also conducted a clinical trial that aimed to determine preand post-transfusion erythrocyte lead and mercury levels in premature infants, correlated with the mercury and lead concentrations in packet red blood cell (pRBC) units. In order to facilitate a comparison, we provided the same lead and mercury thresholds used in the study of Averina et al. In our study, 27% of pRBC units were above the reference limits for mercury, and 22% of pRBC were above the reference limits for lead. The doses of mercury and lead were significantly correlated within the mean difference of preand posttransfusion lead and mercury levels in our study. pRBC units were obtained from the residents of the capitol city of Turkey (Ankara), which is an industrialised city with high environmental pollution. Heavy metal exposure via pRBC transfusions is a global threat for preterm infants, and blood transfusions as a potential source of environmental toxins are increasingly being reported. Very-low-birth weight infants often require blood transfusions in the first few weeks of life, a vulnerable time period for the development of their brains and other critical organs. The safe levels of most heavy metals in preterm infants are unknown and probably much lower than reference doses determined for children and older individuals. Thus, we support the screening of donor blood for lead and mercury levels in preterm infants. A detailed, cost-effective analysis of screening pRBC units for certain environmental hazards should be discussed, considering local differences. If screening donor blood is not feasible, pre-transfusion checklists can be enhanced, or a simple scoring system may be developed, covering risk factors for heavy metals. In Averina et al's striking findings, lead and cadmium levels in donor pRBC units increased 2% and mercury levels increased 3% for every 1-year increase in age. In another study, gender and age were found to be independent risk factors for blood lead concentration. In addition, asking donors for demographics, occupation, smoking, alcohol consumption, living area, nutritional habits and other risk factors may be decisive when deciding on blood transfusions in premature infants.