Volatile Fatty Acids Effective as Antibacterial Agents against Three Enteric Bacteria during Mesophilic Anaerobic Incubation.

The antibacterial effects of a selection of volatile fatty acids (acetic, propionic, butyric, valeric, and caproic acids) relevant to anaerobic digestion were investigated at 1, 2 and 4 g/L. The antibacterial effects were characterised by the dynamics of Enterococcus faecalis NCTC 00775, Escherichia coli JCM 1649 and Klebsiella pneumoniae A17. Mesophilic anaerobic incubation to determine the minimum bactericidal concentration (MBC) and median lethal concentration of the VFAs was carried out in Luria Bertani broth at 37 °C for 48 h. Samples collected at times 0, 3, 6, 24 and 48 h were used to monitor bacterial kinetics and pH. VFAs at 4 g/L demonstrated the highest bactericidal effect (p < 0.05), while 1 g/L supported bacterial growth. The VFA cocktail was the most effective, while propionic acid was the least effective. Enterococcus faecalis NCTC 00775 was the most resistant strain with the VFAs MBC of 4 g/L, while Klebsiella pneumoniae A17 was the least resistant with the VFAs MBC of 2 g/L. Allowing a 48 h incubation period led to more log decline in the bacterial numbers compared to earlier times. The VFA cocktail, valeric, and caproic acids at 4 g/L achieved elimination of the three bacteria strains, with over 7 log10 decrease within 48 h.

Effect of the Inoculum-to-Substrate Ratio on Putative Pathogens and Microbial Kinetics during the Batch Anaerobic Digestion of Simulated Food Waste.

The effects of the inoculum (anaerobic digestion effluent) to substrate (simulated food waste) ratio (ISR) 4.00 to 0.25 on putative pathogens and microbial kinetics during batch mesophilic anaerobic digestion were investigated. Red fluorescent protein labelled (RFPAKN132) Escherichia coli JM105 was introduced as a marker species, and together with the indigenous Clostridium sp., Enterococcus sp., Escherichia coli, and total coliforms were used to monitor pathogen death kinetics. Quantitative polymerase chain reaction was also used to estimate the bacterial, fungal, and methanogenic gene copies. All the ISRs eliminated E. coli and other coliforms (4 log10 CFU/mL), but ISR 0.25 achieved this within the shortest time (≤2 days), while ISR 1.00 initially supported pathogen proliferation. Up to 1.5 log10 CFU/mL of Clostridium was reduced by acidogenic conditions (ISR 0.25 and 0.50), while Enterococcus species were resistant to the digestion conditions. Fungal DNA was reduced (≥5 log10 copies/mL) and was undetectable in ISRs 4.00, 2.00, and 0.50 at the end of the incubation period. This study has demonstrated that ISR influenced the pH of the digesters during batch mesophilic anaerobic digestion, and that acidic and alkaline conditions achieved by the lower (0.50 and 0.25) and higher (4.00 and 2.00) ISRs, respectively, were critical to the sanitisation of waste.

Multiple biomarker responses in female Clarias gariepinus exposed to acetaminophen.

Several authors have documented the presences of acetaminophen (APAP) in both surface and groundwater and have received attention from government agencies and basic authorities across the globe. The impacts of such pharmaceutical products on non-target organism like fish are underestimated as a result of selected investigation using few biomarkers. We evaluated the sub-chronic impacts of APAP in female catfish (Clarias gariepinus) using multiple biomarkers. The exposure of female catfish to APAP induced oxidative stress. Markers such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and total antioxidant capacity (TAC) were significantly higher in all exposed groups. Exposure of Clarias gariepinus to APAPA caused histological alterations in the gills (fusion and shortening of some filaments, hyperplasia of the epithelial gill cells, aneurism, congestion, and epithelial rupture of the gills), liver (apoptotic hyperplasia, sinusoidal congestion, and necrosis of the hepatocytes), and gonad (degenerated follicles and ovarian apoptosis). Furthermore, multivariate results indicated that there was a distinct response from the acetaminophen-exposed female catfish, with over 95% of the biomarkers significantly contributing to the discrimination between the acetaminophen-exposed female catfish and the control groups. Our research provides evidence supporting the use of a multiple biomarker approach to evaluate the impacts of drugs on the health status of exposed fish.

Ingestion and Dermal Cancer Risk via Exposure to Polycyclic Aromatic Hydrocarbon-Contaminated Soils in an Oil-Producing Community, Niger Delta, Nigeria.

There is an intrinsic link between polycyclic aromatic hydrocarbons (PAHs) accumulated in soils and increased health risk to humans after exposure to contaminated soil via ingestion, inhalation of particulates carrying PAHs, and direct contact with polluted soils. However, the assessment of PAH contamination in most developing countries fails to consider health risk assessment. Therefore, a comprehensive study was conducted to determine the concentration, source, toxicity, and human health risks of 16 PAHs in an urban area in Warri, Delta State, in the Niger Delta region of Nigeria. The results showed varying contamination levels for PAH in soil samples from all sampling points, with benzo[a]anthracene (BaP; at 338.81 µg/kg) being the most abundant at all 9 sampling stations. The highest total concentration of PAH was observed at station 5 (1230.98 µg/kg), which was closest to a flow station. Further comparison with PAH contamination standards showed that soils from stations 1 and 2 were weakly contaminated (<600 µg/kg), and soil samples from stations 3, 4, 6, 7, and 9 were moderately contaminated (<1000 µg/kg). Soil samples from stations 5 and 8 were observed to be heavily contaminated (>1000 µg/kg). The BaP estimates for soil samples obtained for stations 3 to 9 were higher than the BaP soil screening value (15 µg/kg), indicating a carcinogenic potential of soil samples. The results also showed that the incremental lifetime cancer risk estimates for PAH in the soil for adults and children were above the recommended threshold (10-4 ) for ingestion and dermal contact, implying that exposure to contaminated soil could lead to cancers in adults and children. Currently, there are no regional or national standards for PAHs in soil that would indicate an increased likelihood for human exposure and subsequent health issues. Environ Toxicol Chem 2021;40:261-271. © 2020 SETAC.

Acute effects of acetaminophen on the developmental, swimming performance and cardiovascular activities of the African catfish embryos/larvae (Clarias gariepinus).

Acetaminophen is a widely used analgesic that has been detected in many water bodies with few reports concerning its potential toxicity to fish. This study sought to assess the developmental, swimming performance and cardiovascular activities of embryo/larvae catfish (Clarias gariepinus) exposed to acetaminophen. The Organization for Economic Development (OECD) Fish Embryo Acute Toxicity Test (OECD 236) was employed. Fertilized embryo were exposed to different concentrations of acetaminophen (0, 0.5, 1, 10 µg/L) for 96 h. Hatching rates of the embryo were observed to decrease with increasing concentrations of acetaminophen. Fish embryo exposed to acetaminophen displayed varying levels of teratogenic effects at different levels of development in a dose-dependent manner. The results also showed a significant (p < 0.05) dose-dependent increase in swimming speed and movement patterns in fish larvae exposed to acetaminophen, with distance travelled in larvae exposed to the highest concentration of acetaminophen (10 µg/L) about eight (8) times the distance travelled by the control larvae, indicating that acetaminophen-induced erratic swimming behaviour in the catfish species. Cardiotoxicity was evident, with a significant reduction in heartbeat rate with increasing concentrations of acetaminophen. The results showed that exposure to acetaminophen resulted in teratogenic, neurotoxic and cardiotoxic effects in embryo/larvae of Clarias gariepinus. The findings suggest that acetaminophen which has recently been detected in many water bodies could potentially impact on survival of aquatic life, especially catfish.

Interactions of trace metals with bacteria and fungi in selected agricultural soils of Egbema Kingdom, Warri North, Delta state, Nigeria.

This study was aimed at investigating the relationship of trace metals with prevalence of bacteria and fungi in polluted farmland of Egbema Kingdom, Delta state. This may contribute to the knowledge on the influence of the microorganism to the arability of agricultural soil from an ecotoxicological viewpoint. Soil samples were analyzed for physico-chemical parameters and trace metals using atomic absorption spectrophotometer (Buck Scientific, 210VGP). The samples were also screened for fungi and bacteria isolates. Trace metals (Fe, Zn, Cd, Ni and Cu) determined in the agricultural soils of Egbema kingdom were below WHO limits. The fungi species with the highest number of occurrence was Aspergillus niger, while the species with the lowest occurrence were Fusarium oxsporium, Penicillium dirty white, and Penicillium sp. The order of abundance of fungi across the stations was Station 2> Station 4> Station 3> Station 1> Station 7> Station 5> Station 6> Station 9> Station 8. The bacteria species with the highest number of occurrence was Proteus sp I, while the species with the lowest occurrence was Alcaligenes sp. which occurred only once at Station 5. The order of abundance of bacteria in the soil samples across the stations was Station 4> Station 3> Stations 5 and 9> Station 2> Station 8> Station 7> Station 6. All trace metals in the agricultural soils of Egbema kingdom were below WHO limits. Fe, Zn, Cd and Ni showed no relationship with the microbial contents of the soil. Various strains of fungi and bacteria (gram positive and gram negative) were observed in the soil samples. An antagonistic relationship was observed between bacteria and fungi. Significant positive correlation occurred between the concentration of copper and bacteria counts indicating that the concentration of copper in the soil might have enhanced the abundance of bacteria in the soil, vice versa. The bacteria might be a promising tool in regulation of soil copper concentration.

Food toxicity assessment of selected canned foods in Nigeria.

Food toxicity assessment was made for frequently consumed canned foods in Nigeria in order to estimate potential human health risks associated with their consumption. Levels of heavy metals (Pb, Cd, As, Fe, Mn and Zn), Nitrate and Nitrite, pH and salt were assessed in randomly purchased samples from groceries stores to represent what is readily available on the market. Nitrates and nitrites were assessed using a Perkin-Elmer spectrophotometer while heavy metal levels were determined using Atomic absorption spectrophotometer. Human health risk was estimated using standard indices; estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and dietary exposure (DE). Results showed varying concentrations of nitrates, nitrites, heavy metals, in all the canned food categories but the level of salt and pH seemed constant. Nitrate, Fe and Cd in all the canned food categories exceeded recommended limit set by EU. Health risk estimations showed EDI values for Cd in all the canned food categories above the tolerable daily intake, while DE for Fe in canned sweet corn, Fe, Zn and Pb in canned beans/peas had values above recommended limits. THQ values for all the canned foods were above 1 in the canned beans/peas while HI was above 1 in the canned fish category. The study revealed the potential for Cd toxicity and risk of non-carcinogenic health effects from canned beans/peas consumption. Constant monitoring of canned foods is therefore imperative considering the growing demand for canned products due to changing lifestyle.

Potential health risk consequences of heavy metal concentrations in surface water, shrimp (Macrobrachium macrobrachion) and fish (Brycinus longipinnis) from Benin River, Nigeria.

Health risk consequences of consumption of heavy metal-contaminated water, shrimp (Macrobrachium macrobrachion) and fish (Brycinus longipinnis) from Benin River in Nigeria were evaluated. Three stations around Koko Community (Abialegbe, Ebenco/Optima and Total Facility) with known anthropogenic activities (industrial and petrochemical installations and loading) were studied. Samples of surface water, shrimp and fish were collected and analyzed using Buck scientific atomic absorption spectrophotometer, model 210VGP. Health risk indices were reported as Estimated Daily Intake (EDI), Target Hazard Quotient (THQ) and Total Target Hazard Quotient (TTHQ). Eight heavy metals were analyzed in water, shrimp and fish. Nickel (Ni) was observed to be the most dominant heavy metal in water, while Iron (Fe) was the most dominant in shrimp and fish. Heavy metal levels in water were below recommended limits set by World Health Organization (WHO) and Standard Organization of Nigeria (SON) except for cadmium (Cd), nickel (Ni) and lead (Pb). Assessment of non-carcinogenic health risk by target hazard quotient (THQ) indicated that THQ estimated for heavy metals in water (dermal exposure) and shrimp were below the threshold value of 1. However, THQ for heavy metals in water (oral exposure) and consumption of fish were above threshold value of 1 indicating potential health risk. Total Target Hazard Quotient (TTHQ) estimated for heavy metals in water (oral exposure) and consumption of fish were above 1 indicating potential non-carcinogenic health risk to consumers. The continuous monitoring of heavy metals in Benin River is of necessity in order to ensure the safety of aquatic organisms and humans who rely heavily on aquatic resources.

Bioactive profiling and therapeutic potential of mushroom (Pleurotus tuberregium) extract on Wistar albino rats (Ratus norvegicus) exposed to arsenic and chromium toxicity.

Mushroom species are valued in gourmet traditions around the world for their unique taste, aroma, nutritional value and medicinal potentials. The bioactive profiling of P. tuberregium mushroom was evaluated to determine it therapeutic effect on Wistar albino rats exposed to arsenic (As) and chromium (Cr) toxicity. Proximate analysis of P. tuberregium showed high composition of carbohydrate (80.24) followed by moisture (21.16), protein (11.46), ash (3.03) and fibre (0.25) content. Phytochemical analysis revealed the presence of polyphenols (2.58), alkaloid (2.46), oxalate (4.25), flavonoid (1.68), tannin (0.38) and Saponin (trace) in trace amount. Mineral analysis yielded variable amounts of Na, Mg, K and Ca. Therapeutics assessment of P. tuberregium to Wistar albino rats exposed to As-Cr toxicity showed improved feed and water intake during the exposure duration. Haematological indices revealed significant increase in platelet (PLT), granulocytes and monocytes while lymphocyte (LY) and red cell distribution width (RDW) were low. Biochemical and redox marker of liver and kidney profiles showed decrease in alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in the liver. Creatinine and urea in the kidney also decrease while total protein increased significantly. Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione S-transferase (GST) decrease in the liver and kidney of the therapeutic group when compared with As-Cr treated rats. The presence of alkaloids and flavonoids in significant amount may have contributed in the therapeutic changes observed in all the parameters. Therefore, our findings conclude that P. tuberregium possessed remarkable effect against As-Cr induced toxicity in albino rats and may be useful in metal toxicity treatment in man and may be concluded that they are therapeutically effective.

Relationship between geosorbent properties and field-based partition coefficients for pesticides in surface water and sediments of selected agrarian catchments: Implications for risk assessment.

Studies on pesticide behavior, adsorption-likelihood, and bioavailability vis-a-vis geosorbent properties and seasons, are critical for understanding pesticide-fate and risks in pesticide-prone environments. We examined the relationship between geosorbent profiles of sediments (percentage sand, silt, clay, organic carbon content) across seasons and occurrence of pesticide residues in surface water and sediment of agricultural catchments at Owan, Ogbesse and Illushi communities of Edo State, Nigeria. Pesticide concentrations were measured monthly in samples of surface water and sediments across the selected sites for 18-months. Pesticide behavior and sorption-likelihoods were examined using partition coefficients Kd (sediment-water coefficient), Koc (sediment-water coefficient normalized for organic carbon) and Log Kow (octane-water coefficient); the relationship between Kd and Koc was also examined. Results of the principal component analysis (PCA) indicated that pesticide levels in sediment and surface water were positively associated with the rainy season, total organic content (TOC), percentage silt and clay in sediment. Field-derived pesticide partition coefficients (Kd < 100 and log Koc < 3) indicated that pesticide species were largely mobile and less likely to be retained in sediments by adsorption. As such, pesticides irrespective of solubility would end up in surface water, increasing risks for pelagic biota and humans sourcing river water for domestic use. Values of Log Kow indicate that organochlorines including DDT, dieldrin, endrin and heptachlor epoxide portend significant bioaccumulation risks to humans and biota across sites. The relationship between Kd and Koc for each site fitted into a quadratic model; it depicted a biphasic behavior of pesticide adsorption and desorption to sediments revealing that concentration of organic carbon across study sites was a limiting factor determining the extent of pesticide adsorption. This study demonstrates that understanding pesticide mobility using field-based partition coefficients could give a clearer picture of pesticide risks to biota and human populations.

Accumulation patterns and risk assessment of metals and metalloid in muscle and offal of free-range chickens, cattle and goat in Benin City, Nigeria.

The use of free range animals for monitoring environmental health offers opportunities to detect exposure and assess the toxicological effects of pollutants in terrestrial ecosystems. Potential human health risk of dietary intake of metals and metalloid via consumption of offal and muscle of free range chicken, cattle and goats by the urban population in Benin City was evaluated. Muscle, gizzard, liver and kidney samples were analyzed for Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb concentrations using inductively coupled plasma mass spectrometer (ICP-MS) while Hg was determined using Hg analyzer. Mean concentrations of metals (mg/kg ww) varied significantly depending upon the tissues and animal species. Human health risk estimations for children and adults showed estimated daily intake (EDI) values of tissues below oral reference dose (RfD) threshold for non essential metals Cd, As, Pb and Hg thus strongly indicating no possible health risk via consumption of animal based food. Calculated Hazard quotient (THQ) was less than 1 (< 1) for all the metals analyzed for both adult and children. However, Cd and As had the highest value of THQ suggestive of possible health risk associated with continuous consumption of Cd and As contaminated animal based foods. Hazard Index (HI) for additive effect of metals was higher in chicken liver and gizzard for children and chicken liver for adults. Thus, HI indicated that chicken liver and gizzard may contribute significantly to adult and children dietary exposure to heavy metals. Principal component analysis (PCA) showed a clear species difference in metal accumulation between chickens and the ruminants. This study provides baseline data for future studies and also valuable evidence of anthropogenic impacts necessary to initiate national and international policies for control of heavy metal and metalloid content in food items.

Human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in smoked fish species from markets in Southern Nigeria.

Polycyclic Aromatic Hydrocarbons (PAHs) levels in four commonly consumed smoked fish species from markets in Southern Nigeria were assessed to evaluate possible human health risks associated with consumption. Varying levels of PAH congeners were observed in the fish tissues with the highest total concentration of PAHs in Scomber scombrus. High concentrations of benzo(a)pyrene was observed in Clarias gariepinus and Ethmalosa fimbriata with values above the guideline value of 0.05 mg/kg. The Dietary Daily Intake (DDI) value for total PAHs (∑PAHs) was highest for S. scombrus while the DDI value for the total carcinogenic PAHs (∑CPAHs) was highest for E. fimbriata. Carcinogenic human health risk assessment using carcinogenic toxic equivalents (TEQ), indicated that consumption of E. fimbriata has a higher potential to cause carcinogenic risks. TEQ values for all the fish species were however, below the estimated screening value (SV) of 3.556 mg/kg, while the estimated cumulative excess cancer risk (ECR) for E. fimbriata and C. gariepinus and PAH4 index for all the assessed fish species exceeded threshold values indicating potential carcinogenic risk from consumption.

Distribution, characterization, and human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in Ovia River, Southern Nigeria.

The levels and distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water, sediment, and fish (Clarias gariepinus) samples from Ovia River, Southern Nigeria, were evaluated, to assess the contamination profile, dietary intake, and human health risks associated with exposure. Results showed that naphthalene, acenaphthylene, and fluoranthene were the most dominant contaminant in water, sediment, and fish, respectively, with mean concentrations (µg/L) of 3.08, 45.4, and 90.7. Spatial distribution showed high occurrence of PAHs in Ekenwan, the downstream station, for all the matrices. Source identification using multivariate analysis revealed mixed patterns of pyrogenic and petrogenic origins. Estimated daily intake (EDI) of PAHs through fish consumption ranged from 2.18 × 10-7 to 5.23 × 10-5 mg/kg/day; values were however lower than the reference dose (RfD) indicating low risk. Estimated values for hazard quotients (HQs) and hazard index (HI) for both non-carcinogenic and carcinogenic risks were below 1 indicating low risk through dietary and non-dietary exposure to water, sediment, and fish from Ovia River. However, estimated HI values for direct ingestion of sediment were above 1, indicating the possibility of non-carcinogenic health risk from exposure. Carcinogenic risk indices also indicated low risk from fish consumption. In spite of the assessed low risk from exposure, continuous monitoring of PAH levels in this water body is imperative to prevent future human health effects.

Assessing the distribution and human health risk of organochlorine pesticide residues in sediments from selected rivers.

Sediment samples from major agricultural producing areas in Edo state Nigeria were analysed for α-HCH, γ-HCH, ß-HCH and ∑DDT with the aim of elucidating contamination profiles, distribution characteristics, carcinogenic and non-carcinogenic risk of these compounds in these regions. Analysis was done using a gas chromatography (GC) equipped with electron capture detector (ECD), while health risk assessment was carried out using the Incremental Lifetime Cancer Risk (ILCR) and the chronic daily intake (CDI). Results showed varying concentrations of α-HCH, γ-HCH, ß-HCH and ∑DDT pesticides in sediment samples with hexachlorocyclohexane (∑HCHs) (4.6 µg/g/dw) being the dominant contaminants as it was widely detected in all samples and stations. Source identification revealed that the current levels of HCHs and DDT in sediments were attributed to both historical use and fresh usage of these pesticides. Risk estimates using ILCR and CDI showed that the risk of cancer and non-cancer effects was highest when exposure route was through ingestion. Furthermore, model projections highlights children as high risk population groups for non-dietary exposure to OCPs. These findings suggests the need for increased monitoring programmes, with a wider scope for both currently used pesticides and legacy/banned pesticides.

Impacts of Acute Exposure of Industrial Chemicals and of Fish (Tilapia Guineensis) Pesticides on The Survival of Fish (Tilpia Guineensis) and Earthworms and Earthworms.

Ecotoxicological effects of industrial chemicals (Rig wash, Oil eater, Nalco, Glycol™) and pesticides (Propoxur, Deltamethrin, Atrazine, Furadan) on Tilapia guineensis (fish) and Aporrectodea longa (earthworms) were tested using the Organisation for Economic Cooperation and Development (OECD) # 203 and 207 protocols. The water and soil ratings indicate that the test chemicals were toxic to the organisms. The estimated 96 hour lethal concentration LC50 values for Rig wash, Oil eater, Nalco EC1304A/COT 505, Glycol, Propoxur, and Deltamethrin were 26.34±0.46, 6.02±0.30, 3.07±0.14, 1.31±0.01, 20.91±0 and 0.01±0 mg/l respectively. In the earthworm bioassay, the estimated 14-day LC50 values for Rigwash, Oil eater, Nalco EC1304A/COT 505, Glycol, Atrazine and Furadan were 80.05±3.5, 151.55±10.7, 172.63±14.2, 63.72±2.43, 4.97±0 and 0.29±0 mg/kg respectively. Safety factors are arbitrarily built in around the LC50 values in order to arrive at environmentally tolerable concentrations. The concentration of a chemical in the receiving environment should not exceed 10% of the LC50. The organisms exposed to the test chemicals showed significant difference when compared with the levels measured in the control group. The observed sensitivity of the test organisms to the chemicals indicates that adherence to standard safety limits/measures should be maintained during use and disposal of hazardous chemicals. This would ensure that the biotic components of the Nigerian Niger Delta ecosystem are prudently protected.

Risk assessment of agricultural pesticides in water, sediment, and fish from Owan River, Edo State, Nigeria.

The distribution of pesticides in water, sediments, Clarias gariepinus, and Tilapia zilli from the Owan River was investigated to evaluate the pollution status and potential hazard in the river system. A total of 16 pesticides were analyzed using gas chromatography (GC) equipped with electron capture detector (ECD). The concentration of pesticide residues ranged from ND to 0.43 µg/l for water samples, 0.82 to 2.14 µg/kg/dw for sediment, 0.04 to 2.34 µg/kg/ww for C. gariepinus, and 0.02 to 1.73 µg/kg/ww for T. zilli. High concentrations of organochlorine pesticides, specifically benzenehexachloride (α-BHC, γ-BHC, and ß-BHC) observed in all environmental media, are an indication of the current illegal use of banned pesticides for agricultural activities in the region. Analysis of data showed a strong correlation (r (2) = 0.7) between total organic carbon (TOC) and total pesticide residues in sediment samples. Meanwhile, risk quotient estimates for heptachlor epoxide, dieldrin, endrin, dichlorodiphenyltrichloroethane (4,4'-DDT), endosulfan I, endosulfan II, endosulfan aldehyde, and phosphomethylglycine showed potential risk to aquatic organism under observed mean concentrations (risk quotient (RQ) ≥ 1). Estimated average daily intake (EADI) for organochlorine pesticides (γ-BHC, heptachlor epoxide, aldrin, dieldrin, and endrin) was above their respective acceptable average daily intake (ADI), while hazard quotient for each of these pesticides was above the unity value (1). This indicates that there is a potential cancer risk for the local residents with life time consumption of pesticide-contaminated fish.

Human health risks associated with residual pesticide levels in edible tissues of slaughtered cattle in Benin City, Southern Nigeria.

Pesticide residues in meat is of growing concern due to possible adverse effects on humans. Pesticide levels were assessed in five edible cattle parts: muscle, liver, kidney and tongue tissues to determine human health risk associated with consumption of these tissues. Health risk estimates were analysed using estimated daily intake (EDI), hazard quotient (HQ) and hazard index (HI) for two (2) age/weight categories: 1-11years/30 kg for children while 70 kg was used for adult. Risks were categorized for non-carcinogenic and carcinogenic health effects and measured at the average, maximum, 50th and 95th percentiles of the measured exposure concentrations (MEC). Total pesticide residues ranged from 2.38 to 3.86 µg/kg (muscle), 3.58 to 6.3 µg/kg (liver), 1.87 to 4.59 µg/kg (kidney) and 2.54 to 4.35 µg/kg (tongue). Residual pesticide concentrations in the tissues were in the order: Liver > Tongue > Muscle > Kidney. The concentrations of all the assessed pesticides observed in the tissues were however lower than the recommended maximum residual limits (MRLs). Human health risk estimations for the children showed EDI values for heptachlor epoxide, aldrin and dieldrin exceeding threshold values. Non-cancer risk posed to children on consumption of contaminated cattle parts showed HQ values for heptachlor epoxide, aldrin, dieldrin and HI values for organochlorines exceeding 1, indicating the possibility of non-carcinogenic health risks to consumers especially children from consumption of cattle meat from the selected abattoirs.

Sublethal effects of endosulfan and diazinon pesticides on glutathione-S-transferase (GST) in various tissues of adult amphibians (Bufo regularis).

Glutathione-S-transferase (GST) plays a key role in cellular detoxification of various xenobiotic chemical, especially pesticides. The study was carried out to assess the effects of the organochlorine pesticide, endosulfan and the organophosphate pesticide, diazinon on the activity of GST of different tissues in the African common toad, Bufo regularis. Toads were exposed for 28 days to varying levels of the pesticides: 0.01, 0.02, 0.03 and 0.04 microg L(-1) for the sublethal test. Activity of GST of toads exposed to the pesticides differentially increased significantly with increasing concentrations. The highest enhancement in GST activity was recorded in the liver followed by the brain, serum, GIT and lungs for both pesticide exposures. The differential increase in GST activity was tissue and pesticide specific. Liver GST increased up to 366% in endosulfan exposed toads and 393% in diazinon exposed toads in the highest concentration (0.04 microg L(-1)). Diazinon pesticide from this study proved to be more toxic than endosulfan pesticide.

Distribution of lindane in water, sediment, and fish from the warri river of the niger delta, Nigeria.

This paper is the first attempt to quantify the levels and the distribution pattern of lindane in the surface water, sediment and fish (Chrysichthys furcatus and Tilapia zilli). The samples were collected from three stations (Ovwian, Ekakpamre, and Ovu) of the Warri River in the western Niger Delta of Nigeria in 2006: during the dry (January-April) and wet seasons (May-August). The analysis included a total of 96 samples made up of 24 samples each for water, sediment, and fish. The pesticide levels were analysed using high performance liquid chromatography to elucidate its distribution in various environmental compartments. Residue levels in the matrices ranged from below the detection limit (BDL) to 1.37microg L(-1) in water, BDL to 12.66 microg g(-1) dry weight (dw) in sediment, BDL to 16.67 microg g(-1)dw in Chrysichthys furcatus, and BDL to 0.15 microg g(-1)dw in Tilapia zilli. The observed values were above the ecological benchmarks (0.01 microg L(-1)) recommended by the Nigerian Environmental Protection Agency and European Union. They were also relatively higher than in previous studies on the Nigerian environment, which calls for regular monitoring of the Niger Delta water bodies.