One of the key findings of this study are high levels of POPs found at all six sites. The sampling revealed very high levels of chlorinated dioxins, brominated dioxins, PCBs, PBDEs, and SCCPs in the eggs of chickens that had foraged in areas at the e-waste scrap yard, open burning dump sites and medical waste incinerators.Some of the highest levels of POPs ever measured in eggs were found in samples collected at the Agbogbloshie e-waste scrap yard in Ghana.
POPs contamination in developing countries can include both domestic and foreign sources. Two potentially large sources are incineration of domestic medical waste and open burning of waste – including electronic waste (e-waste) that comes from developed countries. Both types of sources are listed in the Stockholm Convention as source categories for unintentionally-produced POPs. In addition, electronic waste is known to contain short chain chlorinated paraffins (SCCPs) and flame retardant chemicals listed in the treaty.
Medical waste incineration is a major dioxin source, primarily due to combustion of PVC plastic which is a dominant source of organically bound chlorine. The health sector is also a source of mercury pollution due to improper disposal of mercury-containing thermometers and sphygmomanometers. The Stockholm Convention Guidelines on Best Available Techniques and Guidance on Best Environmental Practices note concerns over small hospital incinerators and that, “Due to the poor design, operation, equipment and monitoring of many existing small hospital incinerators these installations cannot be regarded as employing best available techniques”. In developing countries, medical waste is often not segregated by type and polluting open pit and single chamber incinerators are common. Succesful implementation of medical waste management and non-combustion techniques has been demonstrated in developing countries.
Global estimates of annual e-waste production exceed 40 million tons with an annual growth rate of 4 to 5 percent. The export of electronic waste from developed countries to developing countries, under the guise of ‘recycling’, ‘repair’ and/or ‘reuse’, has effectively become a form of hazardous waste dumping that international agreements such as the Basel Convention or Stockholm Convention were created to prevent.
In this study, free-range chicken eggs were used to investigate POPs contamination in Cameroon and Ghana near medical waste incinerators and open burning dumpsites – including a large e-waste site. Free-range chicken eggs are sensitive indicators of POP contamination in soils/dust and represent an important human exposure pathway. As “active samplers” they can be used to reveal POPs contamination, particularly in areas impacted by dioxins (PCDD/Fs) and PCBs.
This study investigated POPs contamination at the Agbogbloshie e-waste scrap yard (Ghana), medical waste incinerators in Accra (Ghana), Kumasi (Ghana) and Yaoundé (Cameroon), and two open-burning waste dump sites in Yaoundé (Cameroon). To our knowledge, this is the first study to measure POPs in free-range chicken eggs from hens foraging at the Agbogbloshie e-waste scrap yard, and in Yaoundé as well.