Public Health Burden of E-waste in Africa

Abstract

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:

1. 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.

2. 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 polybrominated diphenyl ethers (PBDEs). Brominated flame retardants are persistent organic pollutants (POPs).

3. non-dioxin-like polychlorinated biphenyls. The major use of non-dioxin-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 dibenzo-p-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.

Abbreviations

BFRs

Brominated flame retardants

BLLs

Blood lead levels

CRT

Cathode ray tube

DecaBDE

Decabromodiphenyl ether

DL-PCBs

Dioxin-like polychlorinated biphenyls

DRCs

Dioxin-related compounds

dw

Dry weight

EEFs

Electrical and electronic equipment

lw

Lipid weight

PAHs

Polycyclic aromatic hydrocarbons

PBBs

Polybrominated biphenyls

PBDDs

Polybrominated dibenzo-p-dioxins

PBDEs

Poly-brominated diphenyl ethers

PBDFs

Polybrominated dibenzofurans

PCBs

Polychlorinated biphenyl

PCDDs

Polychlorinated dibenzo-p-dioxins

PCDD/Fs

PPolychlorinated dibenzo-p-dioxins/furans

PCDFs

Polychlorinated dibenzofurans

TBBP-A

Tetrabromobisphenol-A

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 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.

Figure 1.

PRISMA flow diagram indicating the number of articles that were identified, screened and included in this review

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).

Table 1.

Studies Reporting Analytical Levels of Inorganic and Organic E-Waste-Related Toxicants in African Environmental and Human Matrices and Associated Health Effects

	Number of papers	Countries	E-waste-related inorganic toxicants	E-waste-related organic toxicants	Reported health effects
Environmental matrices	25	West African coast, Ivory Coast, Gambia, Ghana, Kenya, Nigeria, South Africa	Fe, Al, Zn, Cu, Pb, Co, Cd, Cr, Mn, Ba, Sn, V, As, Sb, Br, Cl, Hg,	PCB, PBDD, PBDF, DL-PCB, PCDD, PAHS PBDE, Octa-BDE TBBP-A, PBB	-Abnormal thyroid and reproductive function, Reduction of gonadal hormone, Injuries and respiratory symptoms, Cough and chest pain, Headache, stomach discomfort, miscarriage, and cancer -Reduction of gonadal hormone -Depletion of antioxidant reserves -Injuries and respiratory symptoms -Cough and chest pain
Human matrices	12	Ghana, Nigeria, Guinea — Bissau, Morocco	As, Cd, Cr, Hg, Fe, Ag, Al, Be, Cd, Co, Hg, Mn, Pb, Sb, V, Ga, Mn, Mo, Sr, Zn, Cs, Bi, Ba, Ag,	PCB, PBDE, HBCDS, PCDD, PAH

Abbreviations: Br, bromine; Cl, chlorine; Ag, silver; V, vanadium; Ga, gallium; Mo, molybdenum; Sr, strontium; Cs, caesium; Bi, bismuth; PCB, polychlorinated biphenyl; Octa-BDE TBBP-A, Octa-brominated diphenyl ethers Tetrabromobisphenol A; HBCDs, hexabromocyclododecane.

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 ^{(30.3KB, docx)} 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 ^{(30.3KB, docx)} 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, and sedimentary PCB concentrations were highest at a site downstream of an e-waste scrapyard.8 In Ghana, PCBs are introduced to the river in greater proportion from e-waste site than from activities in downtown Accra, with relatively higher PAH concentrations in urban areas with a strong petrogenic fingerprint.8 The high levels of triphenylbenzenes found in Ghana suggest plastic combustion near e-waste scrapyards.8

In addition to PCBs, highly persistent BFRs are of public health concern with respect to their endocrine disrupting action.9 The indiscriminate dumping of cathode ray tube (CRT) casings has added to the plastic explosion in Nigeria. In Nigeria and other African countries, farm land, backyards and waste dumps are inundated with CRT casings. Assessing the presence of PBDEs and how they are handled is therefore crucial. In a study to assess the presence of PBDE and other BFRs aimed at developing an inventory for PBDEs in the plastic components of CRTs from television sets and computer monitors in Nigeria, the authors reported that average PBDE levels (of commercial octabromodiphenyl ether + decabromodiphenyl ether (DecaBDE)) in Nigerian-stockpiled CRT casings were 1.1% for TVs and 0.13% for personal computer CRTs.10 These values exceed the restriction of hazardous substances limit and therefore require separation from the restriction of hazardous substances compliant recycling.10 The Nigerian e-waste inventory of 237,000 tons of CRT plastic contain approximately 594 tons commercial octabromodiphenyl ether and 1880 tons of DecaBDE.10

Sub-Saharan African countries without state-of-the-art recycling plants and with little or no monitoring or measurement capacity for the hazardous contaminants in e-waste are confronted with the challenge of controlling PBDE in plastics and sundry articles/products and in recycling flows. Since Nigeria and other sub-Saharan African countries lack appropriate destruction facilities, open burning or dumping of hazardous wastes and subsequently widespread environmental pollution become inevitable.11,12 During periods of heavy rainfall, much of the site becomes flooded and run-off waters irrigate farm lands. Samples of sediments collected from a shallow lagoon located near the disposal and open burning areas within the Agbogbloshie market, Ghana contained very higher metal concentrations and organic chemicals.13 In Agbogbloshie, Oteng-Ababio et al. found different congeners of PBDEs in both soils and vegetables.14 Soil and ashes samples taken at burning sites in Agbogbloshie showed extremely high concentrations of Cd, Cu, Pb, Sb, and Sn as compared to those typically seen in uncontaminated soil.13

As reported in the Supplemental Material ^{(30.3KB, docx)} , when released into the environment, chemical elements contaminate the air, surface and groundwater, sediment, biota and soil.15

Copper and Pb are the most predominant contaminants among chemical elements in both soil and vegetable samples from e-waste dumpsites.16 The Cu level (4308 mg/kg) exceeded the new Dutch list action value of 190 mg/kg and the soil Pb level (1535 mg/kg) exceeded the Dutch action value of 530 mg/kg.16 Air samples from the Agbogbloshie market located in Accra, Ghana have been analyzed to assess levels of metals and corresponding exposure of workers and people within the vicinity of the market. The site is known to be a dismantling and trading area for end of life electronic items, as well as an informal processing and dumping site. Both air and soil in these and surrounding regions were found to be heavily polluted. Air samples from Agbogbloshie market had high levels of Al, Cu, Fe, Pb, and Zn.17 Over half of the soil samples collected from Agbogbloshie market were above the United States Environmental Protection Agency standard for Pb in soil (400 mg/kg or ppm).18 The lowest Pb level in the soil was 134 ppm and the highest is 18,125 ppm.17 Heavy metal analysis of e-waste samples from Alaba international electronic market and Ikeja computer village in Nigeria showed the presence of Cd, Cr, Ni, Mn, Cu, and Pb at different concentrations, some of which were higher than the limits set by international regulatory authorities.16

Igbo and co-workers investigated the impact of e-waste leachate on micronuclei formation in Tilapia guineensis and levels of heavy metals (As, Al, Ba Cd, Cr, Hg, and Pb) in sediments, water, leachate and aquatic fauna (Tilapia guineensis, Callinectes amnicola and Cardisoma armatum).

An investigation of the interplay of metals (Co, Cu, Fe, Pb, strontium (Sr), and Zn) and bromine (Br) in the formation of dioxin-related compounds (DRCs), including polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and DL-PCBs, as well as non-regulated DRCs such as polybrominated dibenzo-p-dioxins/furans and their monobrominated PCDD/Fs in soils sampled from open burning e-waste sites at Agbogbloshie revealed that the predominant DRCs were PBDFs, PCDFs, PCDDs, and DL-PCBs. 19 Bromine contained in various e-wastes, wires/cables, plastics, and tires strongly influenced generation of many DRCs.19 Soil samples from the e-waste sites at Agbogbloshie are severely polluted by toxic metals and DRCs (PCDD/Fs, polybrominated dibenzo-p-dioxins/furans, and monobrominated PCDD/Fs).19 The summary of PBDFs and PCDD/Fs constituted 94% of the total toxicity equivalent value concentrations of DRCs.19 The PCDF/PCDD ratio indicated a selective formation of PCDFs over PCDDs. The predominant formation of PBDFs rather than PBDDs was also found. Excess formation of monobrominated PCDFs (i.e., high monobrominated PCDF/monobrominated PCDD ratio) may be a common trend pertaining to the burning of e-waste containing BFRs.19

In what is perhaps the first study from the African region on the presence of PBDEs and PCBs in the indoor dust of e-waste recycling facilities, PBDEs were detected in all samples in concentrations higher than levels reported in Guiyu, China in indoor dust from e-waste workshops, and also higher than levels reported by Tue et al.20,21 The following PCBs were also detected in the same South African study: PCB 28, PCB 153 and PCB 180. The most predominant PCBs 153 and 180 have been detected in wild bird eggs in South Africa.22

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).3,5 As reported in the Supplemental Material ^{(30.3KB, docx)} , sources of exposure range from water (including watering sources), aquatic life and farm land. E-waste related toxicants are generally persistent (i.e. resistant to biodegradation) with strong tendency to bioaccumulate in agricultural lands and be available for uptake by grazing livestock and long-range transport.5

Drinking and cooking water from the Alaba international electronic markets and Ikeja computer village have been shown to contain heavy metals and POPs.24,25

Burning poses the highest risk as those who burn e-waste tend to have the highest and elevated blood lead levels (BLL). In Ghana, higher BLL ranges were found among e-waste workers (0.50–18.80 μg/dL) than non-e-waste workers (0.30–8.20 μg/dL).26 Asante et al. found that concentrations of Pb in urine of e-waste recycling workers in Agbogbloshie were significantly higher than those of reference sites.49 In another study by Akortia et al. evaluating concentrations of trace metals in Agbogbloshie, the authors concluded that the surface soils increased in metal concentrations from moderate to high respect to pre-industrial estimated background values, particularly for Cu, Fe and Pb.27 Srigboh et al. characterized exposures to heavy metals and toxic elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, selenium, Zn) in the blood and urine of male e-waste workers and female service workers at Agbogbloshie, and concluded that e-waste workers have elevated Cd and Pb levels in their blood, and elevated As levels in their urine.28 Among exposed workers at Agbogbloshie market, levels of Al, Cu, Fe, and Pb were above the American Conference of Governmental Industrial Hygienists threshold limit (ACGIH TLV). For Al, the ACGIH TLV is 1.0 mg/m³ and the highest reading was 6.5 mg/m³. One of the volunteers had an airborne exposure level of 0.98 mg/m³ or 20 times the allowable ACGIH TLV level of 0.05 mg/m³. Another volunteer had Al exposure levels of 17 mg/m³, seventeen times the ACGIH TLV guideline of 1.0 mg/m³.17 Levels of As, Cd, Cr, and Hg in blood of e-waste workers in Benin, Nigeria have been reported to reduce gonadal hormones.29 Occupational air exposure to Cd and Pb has been linked to chest and respiratory tract associated symptoms, headaches and stomach discomfort in Ghana.30 Skin problems, nausea, allergies, aches and migraine were also reported by e-waste workers and residents within the Alaba international electronic markets and Ikeja computer village in Lagos, Nigeria, probably as a result of exposure to e-waste.31 The investigation of metal urinary levels among primitive recycling of e-waste workers in Ghana (which found elevated Fe, Sb, and Pb concentrations) indicate exposure through the e-waste recycling process. Similarly, high concentrations of these metals have been detected in soil/ash mixtures from the e-waste recycling area in Ghana.32

The most predominant PCBs 153 and 180 have been detected in human breast milk in South Africa.33 Asante et al. analyzed PCBs, PBDEs and hexabromocyclododecane in human breast milk samples in Ghana.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. Two thirds of the workers reported experiencing cough symptoms, while one quarter reported having chest pain.35

Current e-waste handling practices

In Ghana, Nigeria and Morocco, recycling of e-waste often takes place directly on unfortified ground which releases harmful substances directly into the soil. Insulating foam from dismantled refrigerators (primarily polyurethane), CRTs, plastic pellets and old car tires are the main fuels used for fires, contributing to acute chemical hazards and longer term contamination at burning sites.13 Incomplete combustion of chlorinated organic materials, including polyvinyl chloride coated wires, with the reaction catalyzed by metals such as Cu releases dioxins and furans (PCDDs/Fs) to areas surrounding burning sites leading to contamination of surface soils and air.13 Due to very poor infrastructure and inadequate implements, recyclers in sub-Saharan Africa resort to the use of primitive methods (e.g. mechanical shredding and open burning) to remove plastic insulation from copper cables. This technique may release highly toxic chemicals and poses a threat to the environment and human health. The primitive and hazardous techniques used for recycling e-waste lead to elevated levels of e-waste-related (mixtures of) toxicants in the environment, including the food chain, and high body burden in residents and workers at e-waste sites. Very high concentrations of organic toxicants (such as PCBs, PBDEs and PBBs) in air, ash, dust, soil, water and sediments in e-waste recycling sites is partly due to uncontrolled combustion and thermal processing of e-waste.8,12,36 During periods of heavy rainfall, much of the e-waste site becomes flooded and run-off waters irrigate farm lands. E-waste-related toxicants can enter living organisms, from food producing animals to humans through the gastrointestinal tract, as well as lungs and skin. Although inhalation of smoke from open burning of dumpsites seem to be the major route of exposure to e-waste toxicants, drinking of contaminated water, ingestion of vegetables and fruits harvested from dumpsites, and dermal contacts are plausibly additional sources of e-waste related toxicants exposure. When agricultural lands (crops, cereals including rice, other vegetable foods) and animal-rearing activities (farming, fishing and aquaculture) are developed along or downstream of rivers, these should be prioritized in environmental remediation campaigns. Waterways used for domestic uses (drinking, cooking and washing) and irrigation should be prioritized as well. Zoonotic diseases include those which impact human health and result from exposure to toxicants through foods of animal origin.1 Toxicant-related zoonoses are linked with the environment-feed-food chain.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. Toxic and genotoxic levels can induce adverse ecological and human health effects.16,39 Soil leachate and well water samples from the Alaba international and Computer village electronic markets in Lagos State, Nigeria showed both mutagenic and genotoxic properties in plant and animal models.16,24,25,40–42 Exposure of T. guineensis juveniles to varying concentrations of e-waste leachate could be genotoxic to fish.39 Hazardous heavy metals such as As, Cd, Hg, Pb from e-waste are known to cause cancer.43 In their study “Perceived public health effects of occupational and residential exposure to electronic wastes in Lagos, Nigeria” the authors reported cases of cancer among e-waste workers who had spent at least 6 years or more in e-waste sites.31 Similarly, Bandowe and Nkansah reported cases of cancer among those exposed to organic pollutants, as inhalation of e-waste fumes can cause lung cancer.44,45 Decreased lung function arising from lung damage and lung cancer are also associated with PAHs, As, Cd, Cr(VI), Li, and Ni in e-waste.46,47 The extent to which e-waste exposure has contributed to cancer remains largely unknown and should be further investigated.48–50 In human lymphocytes, soil and plant samples from e-waste dumping and processing sites induced significant concentration-dependent increases in DNA damage compared with the negative control.16 Exposure to dioxins, DL-PCBs, perfluoroalkyls and metals (e.g. Cd, Pb) are associated with increased incidence of metabolic syndrome, obesity, type 2 diabetes, hypertension, and cardiovascular diseases.51–53 Exposure to PBDEs in dust has been associated with abnormal thyroid and reproductive functions in both children and adults in Nigeria.54 In addition, heavy metals are endocrine disruptors. Aluminum, As, boron (B), Cd, Co, Cr, Hg, Li, Pb, Sb have been reported to exert negative effects on reproductive parameters of humans and animals. E-waste exposure contributes to rising infertility in sub-Saharan Africa.55 Toxic levels of Pb exposure have shown adverse effects on male reproductive capacity; this is well known despite controversies on the effect of low to moderate doses or route and duration of exposure.56,57 Occupational exposure to Cr(VI) caused significantly higher serum follicle-stimulating hormone concentration and lower sperm count and motility, lower seminal plasma Zn levels, lactate dehydrogenase, and lactate dehydrogenase-C4 according to Marouani et al.58 Mean BLLs of women of childbearing age ranged from 0.83 to 99 μg/dl in sub-Saharan African, with an overall weighted mean of 24.73 μg/dl and 26.24 μg/dl for pregnant women alone.59 Elevated BLLs were associated with the incidence of preeclampsia, hypertension, and malaria.59 Spontaneous abortion has been reported among e-waste workers in Alaba international and Computer village electronic markets in Lagos.31

Developing countries, particularly in Africa, lack data on PCBs in abiotic and biotic matrices. Blood POPs levels of South African pregnant women showed low PCBs levels.60 The serum levels and temporal trends of POPs in adults from Guinea-Bissau showed a significant decrease in total PCB levels (CB-138, CB-153, CB-170, CB-180, and CB-187) measured between 1990 and 2007.61 Total PCBs concentration (sum of 62 congeners) in human milk samples from different parts of Ghana varied between 15 and 160 ng/g lw, with a mean of 62 ng/g lw.34 The PCBs concentrations averaged 82 ng/g lw in Accra, 65 ng/g lw in Kumasi, and 30 ng/g lw in Tamale. Prenatal PCBs and PBDEs exposure are associated with thyroid hormone disruption which affects the initiation and modulation of gene expressions for brain development.62,63

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 Petroleum products have been reported as risk factors for the development of motor neuron disease and other neurodegenerative diseases.67 Elevated soil metals levels have been cited as risk factors in neurodegenerative diseases.68,69 In a multi-center casecontrol study of Nigerian patients and trace metals in patients with Parkinson's disease, Ogunrin et al. demonstrated elevated plasma levels of Cu, Fe, Zn, magnesium, and Mn in patients with Parkinson's disease living in the central, southwest and Niger Delta, Nigeria.70 Notwithstanding that age is thought to be the single most consistent risk factor in Parkinson disease, environmental exposure to metals plays a role in the etiology of Parkinson disease, and increases the prevalence of Parkinson's disease with significant mortality. Finally, e-waste-related toxicants may have deleterious effects on immune and nutritional status, and pose an increased risk of chronic and infectious diseases, e.g. HIV, and harm therapeutic outcomes.71

Figure 2.

E-waste neurotoxicants, their mechanisms and neurological effects during neurodevelopment

Reported/diagnosed health effects of exposure to e-waste related organic and inorganic mixtures of toxicants (Supplemental Material ^{(30.3KB, docx)} ) 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.