Assessment of the Presence of Soil Lead Contamination Near a Former Lead Smelter in Mombasa, Kenya

Abstract

Background.The informal settlement of Owino Uhuru near an abandoned lead smelter attracted international attention due to an apparent lead poisoning event. Despite this attention, the environmental data collected to date do not indicate high levels of residual contamination.Objectives.To further confirm previous findings and determine any necessary risk mitigation measures, an assessment of surface soil lead concentrations was conducted in the community.Methods.Investigators carried out an assessment of the soil in a ~12,000 m2 section of the Owino Uhuru neighborhood over the course of a single day in June 2017 with the assistance of community leaders. Fifty-nine in situ soil measurements were taken using an Innov-X tube-based (40 kV) alpha X-ray fluorescence instrument (pXRF).Results.The assessment found that mean surface soil lead concentrations in areas conducive to exposure were 110 mg/kg (95% CI: 54–168); below United States Environmental Protection Agency and the Environment Canada screening levels of 400 mg/kg and 140 mg/kg, respectively.Conclusions.There is likely no current need for risk mitigation activities in the community. These results could inform discussions on the allocation of public health spending.Competing Interests.The authors declare no competing financial interests. BE, VOO, CN and JSF are employees of Pure Earth. MPT sits on the Editorial Board of the Journal of Health and Pollution.

Conflicting Conclusions or Competing Methodologies? Documenting Soil Lead Pollution in Owino Uhuru, Kenya

“…Meanwhile, Ericson's paper published in the present issue concludes that “ The need for mitigation work in the Owino Uhuru may not be as pressing as presented elsewhere .”2…”

“…This issue of the Journal of Health and Pollution ( JH&P ) presents a follow-up paper submitted by Ericson et al2 on the lead contamination and poisoning situation in the neighborhood of Owino Uhuru in Mombasa County, Kenya. This controversial and politically charged community environmental contamination battle is ongoing, with complex lead exposure pathways still not properly defined.…”

“…However, these papers, while related, are each distinctly different in their methodologies. Ericson et al conducted extensive community lead in soil profiling, while Etiang et al did not 1,2. Meanwhile, Etiang et al conducted actual testing of children's blood in both the “exposed” and “unexposed” neighborhoods, while Ericson relied on the United States Environmental Protection Agency's “Integrated Exposure, Uptake and Biokinetic Model” to predict children's BLLs 1,2…”

“…Ericson et al further used established lead deposition models in an attempt to predict Etiang et al's observed lead in soil observation, with little success 1,2…”

“…What still needs to be determined is the precise exposure source and pathway. However, as Ericson points out “ … the burden of proof to justify interventions should be high ,” especially since “ The residents of Owino Uhuru are subject to myriad environmental health and livelihood risks common to life in informal settlements ” 2. Blood lead levels, soil concentrations and residential lead dust levels reported in 2015 may not apply to conditions in 2017 or even to the present day.…”