Effects of Electronic and Electrical Waste–Contaminated Soils on Growth and Reproduction of Earthworm (Alma nilotica)

Abstract

Informal recycling of electronic waste (e‐waste) contaminates local environments with metals and other organic compounds. The adverse effects on native earthworm populations are poorly understood. The objective of the present study was to determine metal concentrations in soils from e‐waste activity sites in Douala (Cameroon) and assess the effects of these soils on the growth and reproduction of the local earthworm, Alma nilotica. Concentrations of nine metals (arsenic [As], cadmium [Cd], cobalt [Co], chromium [Cr], copper [Cu], mercury [Hg], nickel [Ni], lead [Pb], and zinc [Zn]) were measured in soil samples collected from eight e‐waste activity and two non–e‐waste sites. Earthworms were then exposed to these soils in the laboratory following test guidelines of the Organisation for Economic Co‐operation and Development. Metal concentrations in the e‐waste–contaminated soils were significantly higher than in the non–e‐waste soils. The e‐waste soils were found to have a different soil metal profile (Cu > Pb > Zn > Cr > Ni > Co > As > Cd > Hg) from that of the non–e‐waste soils (Zn > Cr > Cu > Pb > Ni > As > Cd > Co > Hg). Earthworm growth and reproduction were significantly inhibited in organisms exposed to soils from e‐waste sites. Reproduction was particularly affected, with a mean of 8 ± 5.6 offspring/10 worms in the e‐waste–exposed worm groups compared with 90.5 ± 0.7 in non–e‐waste soil worms. Notably, earthworm growth recovered during depuration in clean soil, indicating the possibility of remediation activities. The results demonstrate that soils at e‐waste sites can affect the health of resident worm populations, which may be more sensitive than temperate species. They also highlight the potential of a bioassay‐based approach in monitoring risks at e‐waste sites. Environ Toxicol Chem 2022;41:287–297. © 2021 SETAC

Association between heavy metal uptake and growth and reproduction in the anecic earthworm, Alma nilotica (Grube 1855)

“…4), making it impossible to establish a dose response curve for estimation of growth inhibition effect concentrations. Based on these results, we conclude that growth inhibition may not be a sensitive parameter to measure adverse effects on metal-exposed earthworms, which is also a conclusion reached by other authors (Parihar et al, 2019;Nfor et al, 2022a). However, it was possible to compare the relative potencies of the four metals to Alma nilotica growth which, in decreasing order, was Pb > Cr > Zn > Cu (Fig.…”

“…In Cameroon, for example, increased environmental contamination with heavy metals continues to be a subject of major concern. Studies conducted in various localities of the country (Defo et al, 2015;Mofor et al, 2017;Blanchard et al, 2018;Nfor et al, 2022a;Nfor et al, 2022b) have revealed soils contaminated with heavy metals at non-negligible levels from various anthropogenic activities including mining, industrial activities, addition of chemical fertilizers and pesticides, as well as transportation, dumping and discharge of waste electrical and electronic equipment.…”

“…The elevated concentration of heavy metals in the soil is a potential hazard to the density, growth, survival and reproduction of soil organisms including earthworms (Parihar et al, 2019;Nfor et al, 2022a), which represent the largest component of the animal biomass in soil (Richardson et al, 2020). This is a matter of concern, given the key contributions of earthworms to ecosystem services through, development of soil structures, water regulation, nutrient cycling, pollution remediation, soil aeration, and regulation of soil fertility (Blouin et al, 2013).…”

“…For example, Huang et al (2021) found anecic and endogeic earthworms to be more sensitive and thus more appropriate sentinel organisms to evaluate the risks of soil metal contamination than epigeic earthworms. Alma nilotica, a tropical anecic earthworm species which is widely distributed in Cameroon, has been shown to survive well under laboratory conditions and has potential for use in ecotoxicology testing (Nfor et al, 2022a) but very little published information exists on its sensitivity to important environmental contaminants. We set out to determine the relationship between heavy metal uptake by Alma nilotica and their effects on its growth and reproduction in an effort to link the internal concentration of metals and consequent toxicological effects.…”

Systematic Review and Meta-Analysis of Mercury Exposure among Populations and Environments in Contact with Electronic Waste

“…In other cases, mercury levels on e-waste sites were within recommended guidelines presented by the study but higher compared to control sites. For example, in Douala, Cameroon, mercury concentrations in soil samples were 10-fold higher on the e-waste site compared to the control site but were still within the guideline values set by the Finnish legislation, which provide an approximation of mean values in Europe and are used internationally [35].…”