Occurrences, distribution of PCBs in urban soil and management of old transformers dumpsite in Addis Ababa, Ethiopia

An overview of electrokinetically enhanced chemistry technologies for organochlorine compounds (OCs) remediation from soil

In recent years, electrokinetic (EK) remediation technology has gained significant attention among researchers. This technology has proven effective in the remediation of low-permeability polluted soil. Organochlorines (OCs) are highly toxic, persistent, bioaccumulative, and capable of long-distance migration. They can also accumulate through the food chain, posing significant environmental risks. This paper provides a review of the reaction mechanism of combining chemical technology with EK remediation for the removal of several typical OCs. Furthermore, the factors influencing the efficiency of EK remediation, such as pH and ζ potential, voltage gradients, electrode materials, electrolytes, electrode arrangements, and soil types, are summarized. The paper also presents an overview of recent advancements in the methods of combining chemical technology with EK remediation for the treatment of OCs contaminated soil. Specifically, the research progress in surfactants-combined EK technology, chemical oxidation-combined EK technology, chemical reduction-combined EK technology, and chemical adsorption-combined EK technology is summarized. These findings serve as a foundation for ongoing and future research endeavors in the field. Further exploration and investigation in this area are essential for advancing the field and improving environmental remediation strategies.

Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird species from Lake Ziway, Ethiopia

Abstract

This study presents the assessment of bioaccumulation and reproductive health risk associated with organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) exposure in carnivorous waterbird species. We investigated OCPs and PCBs exposure in muscle tissues of 4 species of carnivorous waterbird species from Lake Ziway, Ethiopia. The influences of trophic position and size on accumulation of organochlorine pollutants are investigated. The result shows that Dichloro-diphenyl-trichloroethanes (DDTs), Endosulfan and PCBs are detected. DDTs constitute the dominant contaminant among OCPs investigated. Trophic position and wing chord length are positively associated with levels of ∑DDTs. Mean levels of ∑DDTs and ∑PCBs vary from 143.9 to 1051.1 ng g−1 wet weight (ww) and not detected (ND)—3.5 ng g−1 ww, respectively. Mean levels of 4,4′-dichloro-diphenyl-dichloro-ethylene (p,p′-DDE), and 4,4′-dichloro-diphenyl-dichloro-ethane (p,p′-DDD) are significantly varied among the bird species. p,p′-DDE contribute 92.3–98.6% of total DDTs. About 26.7% of birds show p,p′-DDE levels above the minimum threshold to cause reproductive failures in birds. Generally, the findings of this study shows that DDT exposure in high trophic levels bird species from Lake Ziway could result in reproductive health risk. The present study may serve as a baseline for future comprehensive exposure and risk assessment studies.

Article Highlights

Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird and fish species from Lake Hawassa, Ethiopia

Abstract

Agricultural, vector-control and industrial activities around Lake Hawassa pose a risk of organochlorine contamination of the lake biota. To assess organochlorine contamination, we measured levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in 3 species of carnivorous waterbird and 3 species of fish. A total of 50 samples of fish and bird species sampled from Lake Hawassa in 2019. We investigated factors influencing accumulation of OCPs and PCBs. Reproductive risk associated with tissue levels of 4,4’-dichloro-diphenyl-dichloro-ethylene (p,p’-DDE) is also estimated. Results show that dichloro-diphenyl-trichloroethane (DDT) is the dominant contaminant found in both bird and fish species. p,p’-DDE is the dominant DDT metabolite in both bird and fish species. Geometric mean of p,p’-DDE varied from 49.8–375.3 and 2.2–7.7 ng g−1 ww in birds and fish, respectively. Average p,p’-DDE level in birds is 33.3 times higher than in fish. p,p’-DDE constitutes 93.4–95.2% of total DDTs in bird species. Degree of exposure, chemical stability, and resistance to environmental and biological degradation could explain higher levels of p,p’-DDE both in bird and fish species. There is significant variation in p,p’-DDE levels among bird and fish species owing to differences in feeding habits, foraging habitat, and lipid content. An increase in DDT levels with increasing size is observed in both bird and fish species. A significant positive association between log-transformed p,p’-DDE, and stable nitrogen isotope ratio (δ15N) values is found. There is no reproductive health risk in bird species as a result of the current levels of p,p’-DDE.

Article Highlights

Major contaminants of emerging concern in soils: a perspective on potential health risks

Soil pollution by the contaminants of emerging concern (CECs) or emerging contaminants deserves attention worldwide because of their toxic health effects and the need for developing regulatory guidelines. Though the global soil burden by certain CECs is in several metric tons, the source-tracking of these contaminants in soil environments is difficult due to heterogeneity of the medium and complexities associated with the interactive mechanisms. Most CECs have higher affinities towards solid matrices for adsorption. The CECs alter not only soil functionalities but also those of plants and animals. Their toxicities are at nmol to μmol levels in cell cultures and test animals. These contaminants have a higher propensity in accumulating mostly in root-based food crops, threatening human health. Poor understanding on the fate of certain CECs in anaerobic environments and their transfer pathways in the food web limits the development of effective bioremediation strategies and restoration of the contaminated soils and endorsement of global regulatory efforts. Despite their proven toxicities to the biotic components, there are no environmental laws or guidelines for certain CECs. Moreover, the information available on the impact of soil pollution with CECs on human health is fragmentary. Therefore, we provide here a comprehensive account on five significantly important CECs, viz., (i) PFAS, (ii) micro/nanoplastics, (iii) additives (biphenyls, phthalates), (iv) novel flame retardants, and (v) nanoparticles. The emphasis is on (a) degree of soil burden of CECs and the consequences, (b) endocrine disruption and immunotoxicity, (c) genotoxicity and carcinogenicity, and (d) soil health guidelines.

Assessment of Perceptions and Cancer Risks of Workers at a Polychlorinated Biphenyl-Contaminated Hotspot in Ethiopia

BACKGROUND

Polychlorinated biphenyls (PCBs) are synthetic and persistent toxic chemicals with a high potential to bioaccumulate in human tissue. There is no existing literature on workers' perceptions and occupational cancer risk due to exposure to PCBs in Ethiopia.

OBJECTIVES

The aim of the present study was to assess workers' perceptions of occupational health and safety measures of PCB management and to evaluate the cancer risk posed by PCBs to workers handling these chemicals in Ethiopia.

METHODS

A total of 264 questionnaires were administered to workers at the study area to obtain information about PCB management. A mathematical model adopted from the United States Environmental Protection Agency (USEPA) was used to assess the potential cancer risk of people working in PCB-contaminated areas.

RESULTS

The results showed that the majority of the workers had little knowledge of safe PCB management practices. Furthermore, 82.6% had not received training on chemical management and occupational health and safety protocols. The association between respondents' responses on the impact of PCBs to the use of personal protective equipment was statistically significant (p <0.005). Accidental ingestion, dermal contact and inhalation exposure pathways were considered in assessing the cancer risk of people working in these areas. The estimated cancer risk for PCBs via dermal contact was higher than for the accidental ingestion and inhalation pathways. The health risk associated with dermal contact was 73.8-times higher than the inhalation exposure route. Workers at the oil tanker and oil barrel area and swampy site are at higher risk of cancer via dermal contact at the 95th centile (879 and 2316 workers per million due to PCB exposure, respectively). However, there is very low cancer risk at the staff residence and garden area via the inhalation route.

CONCLUSIONS

Training programs would help improve the knowledge of workers in the area of occupational health and safety of chemical handling. Further studies on PCBs in the exposed workers will provide information on their blood sera PCB levels and consequently identify potential health impacts.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

Ethics approval was obtained from the Research Ethics Review Committee of Adama Hospital Medical College, Adama, Ethiopia.

COMPETING INTERESTS

The authors declare no competing financial interests.