Efficacy of Vermiremediation to Remove Contaminants from Soil.

BACKGROUND: In addition to improving soil fertility and crop production, earthworms have been found to be useful in the removal of contaminants from soil, known as vermiremediation. Previous studies on vermiremediation have focused primarily on organic wastes, with relatively less attention paid to inorganic contaminants. In addition, some basic terms used in environmental health studies have often not been properly clarified. OBJECTIVES: The present study is a review of the state of the literature on the effectiveness of using earthworms to remediate organic and inorganic (metal) soil contaminants. Earthworms' actions in remediation of organic and inorganic contaminants are described. Some terms that are used interchangeably in environmental health are clarified. The challenges and limitations of vermiremediation are highlighted. METHODS: A systematic literature search was conducted to access online academic publications indexed in Google Scholar, PubMed, Scopus, Clarivate Analytics (Web of Science), ScienceDirect, ResearchGate and Springer Link. A total of 165 publications on the subject matter were accessed, out of which 47 were used for the review. DISCUSSION: Empirical and theoretical information from the literature showed evidence of the significant contributions of earthworms to the removal of soil organic contaminants and metals. Earthworms indirectly facilitate the conversion of organic contaminants by promoting microbial and enzyme activities. Some organic contaminants are directly taken up through dermal and intestinal absorption and accumulated by preferential sequestration in sub-organismic and tissue fractions of earthworms. Metals are directly removed and accumulated by the mechanism of detoxification and sequestration, via metallothioneins induction. The terms 'contaminants' and 'pollutants' have different meanings and should not be used interchangeably. Although vermiremediation presents an ideal clean-up technique, it is limited in application to only mildly contaminated soil environments. Ethical concerns should not pose a serious issue because vermiremediation simply takes advantage of earthworms' natural soil-conditioning abilities. Many vermiremediation processes, especially of organic wastes, are harmless to earthworms, improving the soil for their growth and survival. CONCLUSIONS: Vermiremediation presents a good long-term biological option to clean up mildly contaminated soil. It may be deployed as a secondary measure to rid the soil of residual contaminants after applying physicochemical remediation techniques to an overtly polluted soil environment. COMPETING INTERESTS: The authors declare no competing financial interests.

Comparative Assessment on Mechanism Underlying Renal Toxicity of Commercial Formulation of Roundup Herbicide and Glyphosate Alone in Male Albino Rat.

There have been major concerns that the nephrotoxicity of commercial formulations of Roundup herbicide is due to the active ingredient glyphosate. We therefore investigated and compared the mechanisms underlining the nephrotoxicity of Roundup herbicide and glyphosate alone in rat. Fifty-six adult male rats randomized into 7 groups of 8 rats per group were exposed to Roundup formulation and glyphosate alone daily by gavage at 3.6, 50.4, and 248.4 mg/kg body weight (bw) of glyphosate concentrations for 12 weeks with distilled water administered to the control group. Kidney biomarker (serum urea and creatinine, plasma cystatin-C, and neutrophil gelatinase-associated lipocalin), oxidative stress indices in the kidney tissue, activities of kidney membrane-bound enzymes (Mg-adenosine triphosphatase [ATPase], Ca-ATPase, Na/K-ATPase, and total ATPase), and histopathological changes in the kidney were monitored. Glyphosate concentration in the kidney was quantified by high-performance liquid chromatography with ultraviolet detection. Significant ( P < 0.05) alterations in the levels of the kidney biomarker, oxidative stress markers, and membrane-bound enzymes were observed in the rats exposed to Roundup compared to the rats exposed to glyphosate alone. Rats exposed to Roundup accumulated more glyphosate residue in their kidney tissue. Severe histopathological lesions were only seen in the kidneys of rats exposed to Roundup. The nephrotoxicity observed cannot be due to the active ingredient in the Roundup formulation, as glyphosate alone has virtually no effect on the renal function of the exposed animals. Therefore, the general claim attributing nephrotoxicity of a glyphosate-based herbicide to its active ingredient should be discouraged.

Effect of gasoline fumes on reproductive function in male albino rats.

The increase in the frequency of exposure to gasoline fumes and the growing incidence of infertility among humans has been a major concern and subject of discussion over the years in Nigeria. We therefore present the reproductive effect of gasoline fumes on inhalation exposure in 40 male albino rats. The rats were randomized into five experimental treatments (T) with eight rats per treatment. T1 (control) was exposed to distilled water while T2, T3, T4, and T5 were exposed to gasoline fumes in exposure chambers for 1, 3, 5, and 9 h daily respectively for 12 weeks. Serum level of testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin, oxidative stress markers in the testicular tissue, epididymal sperm health assessment, and testicular histopathology of the rats were used as a diagnostic marker of reproductive dysfunction. Significant (p < 0.05) alterations in the levels of all the reproductive hormones and oxidative stress markers assayed were observed in rats exposed to gasoline fume. Significant reductions (p < 0.05) in sperm count and percentage motility in the exposed rats were observed. Significant (p < 0.05) increased in abnormal sperm cells characterized by damaged head, bent tail, damaged tail, and without head were also observed in the exposed rats. Histopathologically, severe degenerative testicular architectural lesions characterized by alterations in all the generations of sperm cells and reduction of interstitial cells were seen in the exposed rats. Gasoline fume is thus said to interfere with spermatogenesis and impair fertility in male gonad.

Reproductive toxicity of Roundup herbicide exposure in male albino rat.

The incidence of infertility in human is on the increase and the use of Roundup herbicide and presence of its residues in foodstuff is a major concern. This study therefore aim to assess the effect of Roundup on the reproductive capacity of 32 adult male albino rats randomized into 4 groups of 8 rats per group orally exposed to Roundup at 3.6mg/kg body weight(bw), 50.4mg/kgbw and 248.4mg/kgbw of glyphosate concentrations for 12 weeks while the control group was given distilled water. Serum level of reproductive hormone (testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin), oxidative stress indices in the testicular tissue, epididymal sperm morphology assessment and testicular histopathology of the rats were used as a diagnostic marker of reproductive dysfunction. Significant (p<0.05) alterations in the level of all the reproductive hormones and oxidative stress markers assayed were observed in rats exposed to Roundup. Significant reductions (p<0.05) in sperm count, percentage motility and significant (p<0.05) increased in abnormal sperm cells were observed in the exposed rats. Histopathologically, severe degenerative testicular architectural lesions were seen in the Roundup exposed rats. Roundup may interfere with spermatogenesis and impair fertility in male gonad.