Public Health Burden of E-waste in Africa.

Background
Environmental impacts from informal e-waste recycling are increasing in Africa. E-waste handling and disposal exposes people to highly toxic cocktails of heavy metals, brominated flame retardants, non-dioxin-like polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PBDF) and dioxin-like polychlorinated biphenyls (DL-PCB). Most of these compounds are endocrine disrupters, and most are neuro- and immune-toxic as well.


Objectives
Informal e-waste recycling in African countries is a serious public health threat. The present paper reviews the extent of e-waste exposure in Africa and related impacts on people, animals and the environment.


Methods
Four electronic databases (PubMed, Science Direct, Scopus, Google Scholar) were searched for publications related to e-waste and human health in Africa. Search terms included 'e-waste in Africa', 'e-waste in developing nations', 'public health and e-waste', 'environment and e-waste', and 'e-waste and health'.


Discussion
Elevated levels of e-waste pollutants in water, air, soil, dust, fish, vegetable, and human matrices (blood, urine, breast milk) indicate that not only are e-waste workers at risk from exposure to e-waste, but the general population and future generations as well. Headache, cough and chest pain, stomach discomfort, miscarriage, abnormal thyroid and reproductive function, reduction of gonadal hormone, and cancer are common complaints of those involved with the processing of e-waste.


Conclusions
The evidence presented from the reviewed studies illustrates the extent of the human health and environmental risks posed by e-waste in Africa. There is a need for a regulatory framework including specific legislation, infrastructure and protocols to safely recycle and dispose of e-waste in sub-Saharan African countries.


Competing Interests
The authors declare no competing financial interests.


Introduction
Modernization and civilization have led to a growth in technology. Electronic gadgets have been developed to aid information and communication ranging from radios, computers and peripheral items, telephones, televisions, and other household consumer electronics and vehicles. The production, commercialization, use, recycle, and disposal of electrical and electronic equipment (EEEs) have increased exponentially in the last decades. The rapid increase of new technologies makes EEEs obsolete, sometimes within days of purchase. Large quantities of e-waste end up dumped in low income countries, where second-hand materials come mixed with broken parts. Most of the electronic gadgets used in Africa have second hand value and reach their half-life soon after they are imported and go obsolete, contributing to the rapid increase of e-waste in Africa. Once it is beyond repair, e-waste is dumped and presents a hazard to the environment, animals and humans. 1 A large range of toxic chemicals (toxicants) are associated with this e-waste. 2 Inorganic and organic toxicants can be released from e-waste, posing serious risks of harm to human health and the environment. 3,4 Electrical and electronic equipment are mostly made from petrochemicals, glass, electrical and electronic components which are not biodegradable, including: i) chemical elements such as aluminium (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), cadmium (Cd), hexavalent chromium (CrVI), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), mercury (Hg), nickel (Ni), tin (Sn), zinc (Zn) and groups like the platinum group elements and rare earth elements.

Review
ii) brominated flame retardants (BFRs). These have historically been added to materials, especially plastics (thermoplastic components, cable insulation) in computers to improve their fire resistance. The main examples are polybrominated biphenyls (PBBs), tetrabromobisphenol-A (TBBP-A), and poly-brominated diphenyl ethers (PBDEs). Brominated flame retardants are persistent organic pollutants (POPs).
iii) non-dioxin-like polychlorinated biphenyls. The major use of nondioxin-like polychlorinated biphenyls has been as dielectric fluid in electrical equipment, particularly capacitors and transformers, in heat transfer fluids and as plasticizers and additives in lubricating and adhesives and plastics. Non-dioxin-like polychlorinated biphenyls are also POPs.
Other e-waste-related toxicants arise from common e-waste practices like e-waste combustion, such as various congeners of polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polybrominated dibenzop-dioxins (PBDDs), polychlorinated dibenzofurans (PCDFs), polybrominated dibenzofurans (PBDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs). 5 The volume of EEEs that have accumulated as waste worldwide is also of great concern. High-volume informal recycling of e-waste has been reported in many countries, including China, Ghana, India, Nigeria, the Philippines, Thailand, and Vietnam. E-waste management is one of the most rapidly growing pollution problems worldwide. 2,5 African exposure scenarios have been difficult to assess until recently due to limited information on e-waste-related exposures in major e-waste sites such as West Africa. The situation is changing, and the African scientific community has begun to collect analytical evidence on e-waste contamination of environmental media and human internal exposure, as well as associated health outcomes.
Based on the above, this work summarizes current e-waste contamination and recycling practices in Africa, the measured hazards associated with such activities, and reported/diagnosed health effects in resource-poor and technologically challenged countries in sub-Saharan Africa. This review will not only add to the foundation of knowledge, but can also support public health initiatives in sub-Saharan Africa.

Methods
Four electronic databases (PubMed, Science Direct, Scopus, Google Scholar) were searched for publications related to e-waste and human health in Africa. Search terms included 'e-waste in Africa' , 'e-waste in developing nations' , 'public health and e-waste' , 'environment and e-waste' , and 'e-waste and health' . Duplicates from papers (64 in PubMed, 1306 in Science Direct, 1306 in Scopus, 3750 in Google Scholar) were removed, and 364 articles remained. Among these, only those published in the English language from 2011 to 2018, and those relating to the African continent were included. After selection according to the above method of identification and criteria for selection of studies ( Figure 1), papers were screened for both analytical levels of inorganic and Review organic e-waste toxicants associated with specific components of EEEs found in environmental and human matrices in Africa, and e-waste associated human health effects in Africa.

Results
Applying the screening methods describes above, 37 papers were screened in the present review. Of these, 25 papers reported analytical levels of e-waste-related toxicants environmental matrices in Africa, and 12 reported on human matrices in Africa ( Table 1).
Nigeria (Alaba international electronic market and Ikeja computer village in Lagos) and Ghana (Agbogbloshie, Accra) have been reported to be major e-waste dumpsites in Africa. 6,7 The Supplemental Material presents published African analytical data (notably from Ghana, Nigeria, Kenya, Morocco and South Africa) on primary e-waste related toxicants and reported/diagnosed health effects in exposed (sub)populations. In particular, the first table in the Supplemental Material focuses on inorganic and organic toxicants found in environmental (including food) matrices, whereas the second table focuses on inorganic and organic toxicants in human matrices.

Discussion
In their study on plastic resin pellets collected from 11 beaches covering the entire Ghanaian coastline, Hosoda and co-workers analyzed polychlorinated biphenyl (PCBs) and found that PCB concentrations (∑13 congeners) were higher in Accra, the capital city, and Tema (39-69 ng/g-pellets) than those in rural coastal towns (1-15 ng/g-pellets), which are close to global background levels. 8 All PCBs concentrations in plastic pellets manufactured near Accra were reported to be higher than global background levels, indicating local inputs of PCBs. 8 In the same study, river sediments were also analyzed for PCBs together with molecular markers, In addition to PCBs, highly persistent BFRs are of public health concern with respect to their endocrine disrupting action. The PCB levels in sediments from Accra (0.57-32.2 ng/g dry weight (dw)) are lower than in some developed countries and large e-waste sites in China, but higher or comparable with levels in Japan or developing countries (Vietnam, Indonesia, Senegal, India, Philippines). 8 The highest PCB level in Accra (32.2 ng/g dw) exceeded the effects range-low level of sediment quality guideline (22.7 ng/g) 23 of the US National Oceanic and Atmospheric Administration (NOAA). This observation suggests that the likely biological effect of PCBs cannot be ignored near e-waste sites in developing countries.

Human exposure
Humans come into contact with e-waste toxicants in air (e.g. open burning), soil (e.g. disposal), water via ingestion (e.g. food chains contamination due to disposal and primitive recycling processes), inhalation, and dermal absorption (e.g. dust and direct exposure of workers who labor in primitive recycling areas and their families).  34 Although the PBDE (0.86-18 ng/g lipid weight (lw)) and PCB (15-160 ng/g lw) levels were lower than values in Chinese e-waste processing sites, breast milk levels found in Ghana (a much less industrialized country) are considered of public health importance. Following the detection of somewhat high levels of PBDEs in breast milk samples in three main regions in Ghana, the authors argued that in addition to neurodevelopmental deficits and cancer, a toxicological endpoint of concern for environmental levels of PBDEs is likely also thyroid hormone disruption. 34 The source of these pollutants is believed to be the informal handling and disposal of e-waste. 34 Polycyclic aromatic hydrocarbons metabolites were analyzed in the urine of residents and workers from an e-waste processing site in Agbogbloshie and were found to be significantly higher than a control group.  37 The increasing urbanization of many cities in sub-Saharan Africa has made land for urban agriculture economically prohibitive with attendant socioeconomic pressures for those who engage in the practice for their livelihood. 14 As a result, many urban farmers are compelled to live and work in available and affordable but dangerous locations, without the necessary resources to protect themselves and/or guarantee the safety of their crops. The ultimate desire to feed themselves overrides safety and wellness considerations. Most farmers have dammed highly contaminated drains to harvest water to irrigate their farms, and the lands on which they farm are affected by e-waste recycling activities of significant public health relevance. 14,38 E-waste pollutants are found at significant doses in human serum, blood, hair, placenta, breast milk, and umbilical cord blood, indicating that exposure to e-waste presents a risk for the present as well as for future generations. Most e-waste-related toxicants are persistent (slow excretion/ metabolic rate) and therefore can bioaccumulate in living organisms (e.g. grazing animals and humans) as well as biomagnify in the food chain (e.g. fish). In addition, bioaccumulation results in the presence of multiple toxicants in the same organism, with potential mixture (additivity/ potentiation) effects. E-waste does not constitute a contamination "event", but a background exposure that exceeds the (environmental, animal, human) detoxification rate, thus making the burden continuously re-established and amplified. The management of e-waste implies long-range initiatives, from the expected international regulation of the e-waste flow to the implementation of proper infrastructures and protocols for disposal and recycling and the remediation of environmental compartments on a large scale through innovative detoxification technologies.

Health effects
Chemicals in e-waste materials can accumulate in water, soil, and surrounding vegetation. Among other health impacts (e.g. endocrine disruption, immunotoxicity), e-waste acts as a neurotoxicant in neurodevelopment and neurodegeneration. Along with endocrine disruption, neurotoxicity is considered the main e-waste-related health burden issue. 64 Heavy metals accumulate and substitute nutritional essential elements, for example calcium is substituted by Pb, Zn is substituted by Cd, and majority of trace elements are substituted by Al. Consequently, accumulated heavy metals destroy various and vital metabolic processes, and alter activity of hormones and essential enzyme's function along with creating antioxidant imbalance. 65 These mechanisms ultimately alter the synthesis of neurotransmitters and their use in the body thus altering central nervous system functions. Figure  2 presents e-waste neurotoxicants, their mechanisms and neurological effects during neurodevelopment. The neurotoxicological mechanisms of the effect of e-waste's mixture of toxicants are complicated and may be synergistic.
Other mechanisms related to molecular biology and signal transduction may be involved in neurodegeneration. In a study of motor neuron disease in Nigeria, most patients were found to have lived in Warri, an area located in Nigeria's Niger Delta that is associated with petroleum activities. Some of these subjects worked at the National Petroleum Corporation. 66   Reported/diagnosed health effects of exposure to e-waste related organic and inorganic mixtures of toxicants (Supplemental Material) seem well in line with those expected based on toxicology. 12 Headache, cough and chest pain, stomach discomfort, miscarriage, abnormal thyroid and reproductive function, reduction of gonadal hormone and cancer are common complaints of the e-waste community, including vulnerable populations like pregnant women and children.

Conclusions
Dwindling economic fortunes, poverty and population explosion have led to a high level of unemployment in Nigeria and many sub-Saharan African countries. This has made e-waste handling, recycling and associated activities inevitable alternatives. The recycling of electronic waste, or e-waste, remains a major source of survival for the poor in urban areas in developing countries. Unfortunately, this economic activity presents severe risks to their health, as well as that of the general population and the environment. Most e-waste recycling sites in sub-Saharan Africa consist of a large number of support facilities such as housing and restaurants, street trading, food and beverage vendors, and therefore chemical exposure extends beyond e-waste workers. These communities, including women and children, comingle in these sites on a daily basis.
Until recently, there has been no available data on chemical exposure at e-waste recycling sites in sub-Saharan Africa, but this scenario is changing and the scientific community in Africa has begun to address the problem of e-waste. Human biomonitoring of metals and BFRs, as well as dioxins, PAHs, PCBs and furans in e-waste sites is recommended to validate the growing evidence of the negative environmental impacts and health concerns arising from uncontrolled informal e-waste recycling and disposal.