**5. Conclusions**

Our study showed that PBDE concentrations at the e-waste recycling sites were elevated compared to those detected at the control sites by 100 s to 1000 s times, with BDE-209 being the most abundant in all the samples and at all the sites. There was a significant difference in concentrations of PBDEs at the various e-waste activities sites in this decreasing order: burning sites > dismantling sites > repair sites > control sites. This proves that the type of activities at the sites influences the level of PBDEs, with burning activities having the most effect. This study demonstrates that crude recycling of e-waste contributes significantly to emissions of organic pollutants in the environment. Comparing our results with past studies in the same locations, not much has changed in the the PBDE concentrations considering that PBDE use in electronics has been banned, suggesting that the situation calls for urgen<sup>t</sup> action. Our results sugges<sup>t</sup> that the informal e-waste recycling has negative impacts on the enviroment and consequently on health. There is an urgen<sup>t</sup> need for more effective actions to stop open burning of e-waste and to reverse or stop the environmental deterioratation as a result of informal e-waste recycling. One way to stop unsafe recycling of e-waste is to adopt a bottom-up approach in stopping these unsafe practices by: (1) for the formal institutions to appreciate and work with the informal sectors (2) to the create awearness on the potential health risks of unsafe recycling of e-waste among th e-waste workers.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1660-4601/16/3/360/s1, Table S1a: Summary of the Physicochemical parameters (mean of pH and Total Organic matter content) of the samples at the study locations. No standard deviation is given if n=1., Table S1b: Physicochemical parameters (pH and Total Organic Matter Content) of the samples at the study site., Table S2: PBDE median concentrations (ng/g dry weight) across various e-waste sites; and exceedance (Ex) of PBDE concentrations in soil and dusts across various e-waste sites compared to control sites in Lagos., Table S3: PBDE median concentrations (ng/g dry weight) across various e-waste sites; and exceedance(Ex) of PBDE concentrations in soil and dusts across various e-waste sites compared to control sites in Ibadan., Table S4: PBDE median concentrations (ng/g dry weight) across various e-waste sites; and exceedance (Ex) of PBDE concentrations in soil and dusts across various e-waste sites compared to control sites in Aba., Table S5: F-values of the two-Way ANOVA for PBDE concentration in all sample types across the Activity sites (burning. dismantling. repair sites)., Table S6: F-values of the two-Way ANOVA for PBDE concentration in top soils across the locations(Lagos. Ibadan. Aba) and Activity sites (burning. dismantling. repair. and control sites)., Table S7: F-values of the two-Way ANOVA for PBDE concentration in floor dust across the locations(Lagos. Ibadan. Aba) and Activity sites (dismantling and repair sites)., Table S8: Correlations between PBDEs congeners. ∑13PBDE. pH and TOC (Top soils).

**Author Contributions:** This study is part of the Ph.D. research of C.M.O. C.M.O. conceived the study, carried out the literature review, developed data collection and analyses plan, collected data, analysed the data, drafted the manuscript and provided critical revision to the manuscript. W.J.G.M.P., P.M.V.B., M.V., and O.O. are the supervisors and were involved in study design, data collection plan, revision of the various versions of the manuscript, and made contributions to the manuscript. Q.X. and J.C. carried out the laboratory analysis. P.M.V.B. *Int. J. Environ. Res. Public Health* **2019**, *16*, 360

was involved in all stages of the write-up and critical revision of the manuscript, and contributed to the data analyses and advanced statistical procedures.

**Funding:** This research was funded by NUFFIC (Netherlands Universities Foundation for International Cooperation), research gran<sup>t</sup> CF9420/2014 NFP-PhD.14/37.

**Acknowledgments:** Data for this paper was obtained within a research project supported by the Netherlands Fellowship Program of NUFFIC (Netherlands Universities Foundation for International Cooperation), research gran<sup>t</sup> CF9420/2014 NFP-PhD.14/37. The authors acknowledge the various associations of second-hand electronics dealers, scrap dealer associations in each location for their cooperation and for allowing the soil and dust samples to be collected from the work sites, research assistants for helping out in sample collection, and laboratory assistants for helping out with the data analysis.

**Conflicts of Interest:** The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
