“Subsistence hunting with lead-based ammunition in tropical rainforests and health risks for global indigenous people (IndiLead)” (Spanish Ministry of Science and Innovation, 2023-2026)
Summary
Lead (Pb), a cumulative neurotoxin, is the most widespread toxic metal in the world. Chronic exposure to lead, even at low levels, is associated with an elevated risk of cardiovascular and chronic kidney disease in adults and of impaired neurodevelopment and subsequent cognitive and behavioural development in the fetus and young children. For years, leaded gasoline was the dominant source of human exposure to Pb. However, nowadays, the most important source of Pb release into soil at the global level is the use of lead-based ammunition. There is overwhelming evidence that the discharge of lead bullets and shotgun pellets into the environment poses significant risks of lead exposure to wildlife in industrialized countries (in particular, waterfowl, raptors and scavenging birds).
The best available scientific evidence also demonstrates that the discharge of lead-based ammunition into the environment poses significant risks of elevated lead exposure to hunters and game meat consumers in industrialized countries. Lead-based ammunition fragments are retained in and easily ingested along with game meat prepared for human consumption. Elevated blood lead concentrations have been found in humans that regularly consume game in Europe and North America and dietary lead from spent ammunition has been recognized as the main remaining pathway of human lead exposure in these countries. However, the severe health and environmental risks from lead-based ammunition are believed to be circumscribed in industrialized countries where lead pellets have been widely used since the early 15th century.
The introduction of firearms and lead shot in the Amazon and the global tropics took place only in the early 20th century and the daily use of shotguns for subsistence hunting was not widespread until the last decade of the 20th century due to their prohibitive cost for indigenous people. Nevertheless, our research team recently (and for the first time) demonstrated that lead-based ammunition has also resulted in high tissue Pb levels in wild game species in remote areas of the Peruvian Amazon (Cartró-Sabaté et al. 2019, Orta-Martínez et al 2021) and Cameroon (Orta-Martínez et al submitted). Since subsistence hunting represents one of the main sources of protein intake for rural and indigenous communities in the world tropical rainforests, including the Amazon and beyond, we hypothesise that blood lead levels (BLL) may be high in indigenous hunting communities of the global tropical (Hypothesis 1 – H1) and, that lead-based ammunition may be the main source of lead exposure for these already vulnerable and marginalized populations (Hypothesis 2 – H2), posing significant health risks to the human populations of the world tropical rainforests that rely on subsistence hunting for their daily protein intake.
INDILEAD will provide prominent and sound environmental and epidemiological results on the risks posed to human health by lead-based ammunition for subsistence-hunting communities in the tropical rainforests of Peru, Cameroon and Indonesia. INDILEAD will analyze BLL in human blood samples from indigenous communities of the tropical forests of Cameroon (Baka indigenous people), Peru (Yagua indigenous people from the Yavarí river basin) and Indonesia (Punan-Tubu indigenous people).To assess Pb sources and routes of exposure, Pb isotopes will also be analysed for these blood sample sets.