The contamination of the ecosystem is a major challenge to the environment itself and its associated biota 12. Environmental pollution is caused mostly by anthropogenic activities and to lesser effect by natural effects 3 especially in Nigeria. Contaminations associated with anthropogenic activities is significantly brought about by industrialization, unsustainable agricultural practices, population growth and urbanization 45. Basically toxins are materials/substances that influence the physical, compound and natural qualities of biotic segments of the biological system just as the abiotic constituents, subsequently representing a danger to human wellbeing, and other creatures including plants, animals and microbes 3.

In the Niger Delta region of Nigeria, solid waste management is a major concern to environmentalist. Several wastes streams resulting from human activities are discharged into the environment (soil and surface water) where they cause an alteration or impact. The use of chemicals has also increased in the recent years. For instance, the use of pesticides has increased and its use depends on the target organism. Conventionally, rodenticides, herbicides, insecticides acaricides and fumigants are used to control rodents, weeds, insects, ticks and grain insects, respectively. The remains and empty cans of chemical substances such pesticides are careless discharged into the environment, and they can find their way to the aquatic organisms through runoff where they may impact on the aquatic organisms 678. Basically, the constituents of the chemicals depend on the intended use.

Aluminum phosphide is a fumigant used in preserving grains 9 such as maize. Aluminum phosphide is toxic to both target and non-target organisms. Aluminum phosphide has been described as suicide poison with no effective treatment remedy when ingested 10. Aluminum phosphide is known as “trebor” by local farmers in some parts of Nigeria 11. Authors have reported that aluminum phosphide could be mistakenly grounded with maize during the processing of fish feed 1112. The authors reported that Aluminum phosphide could cause an alteration in cyto-achitecture of the vital organs in animals. Probably due to its toxicity, there is a concern associated with its misuse 9. The lethality of aluminum phosphide is related with the arrangement of phosphine gas when it gets in contact with dampness 91011.

Fish have been generally used to survey the lethality of chemicals in the aquatic environment. Therefore, this study assessed the impact of aluminum phosphide on the transferases in liver and muscle of Parophiocephalus obscurus.

(Figure 1) shows the concentration of Aspartate aminotransferase in liver and muscle of Parophiocephalus obscurus exposed to sublethal concentrations of Aluminum phosphide for 14 days. In the liver, the concentrations of aspartate aminotransferase at 0.00 mg/L, 4.20 mg/L, 6.30 mg/L and 8.40 mg/L were 94.50±6.44µ/L, 134.47±15.27 µ/L, 106.47±9.21 µ/L and 31.00±3.46 µ/L, respectively. There were significant variations (p<0.05) across the concentrations. Multiple comparisons showed no significant variation between 0.00 mg/L and 6.30 mg/L, and between 4.20 mg/L and 6.30 mg/L. While in the muscle the concentrations of Aspartate aminotransferase were 107.50±9.24, 92.00±6.93 µ/L, 116.50±8.95 µ/L and 146.33±9.33 µ/L at 0.00 mg/L, 4.20 mg/L, 6.30 mg/L and 8.40 mg/L, respectively. Statistically, significant difference (p<0.05) was noticed across the concentration. Pairwise comparison reviewed no significant variations between 0.00 mg/L, 4.20 mg/L and 6.30 mg/L, and between 6.30 mg/L and 8.40 mg/L.

On comparative analysis, the levels of Aspartate aminotransferase in the liver and muscle were significantly different (p<0.05) at 0.00 mg/L and 8.40 mg/L, and not significantly different (p>0.05) at 0.420 mg/L and 6.30 mg/L (Table 1). The levels of the Aspartate aminotransferase across the various concentration of the toxicant significantly differ in the muscle and liver of Parophiocephalus obscurus. This suggests the effects of Aluminum phosphide on the liver and muscle aspartate aminotransferase.

Basically, aspartate aminotransferase is an essential enzyme found in many cells of the body especially in the liver, muscle, and kidney. Typically, the aspartate aminotransferase tends to be low in normal condition, but when an organism is exposed to stressed condition and the liver and other cells that contain significant amount of aspartate aminotransferase is adversely affected, its level will be elevated. The trend observed in this study is in accordance with those previously reported: Clariasgariepinuswere exposed to Fluazifop-p-Butyl 8 and phenol 7; and Clariaslazerawere exposed to dimethoate 16. In this study, the aspartate aminotransferase was observed in both muscle and liver at high concentration in most of the concentrations. This suggests the effect of aspartate aminotransferase on the liver and muscle cells.

The concentrations of alanine aminotransferase in liver and muscle of Parophiocephalus obscurus exposed to sublethal concentration of Aluminum phosphide for 14 days are presented in (Figure 2). At 0.00 mg/L, 4.20 mg/L, 6.30 mg/L and 8.40 mg/L the concentration of alanine aminotransferase in the liver were 40.00±1.15µ/L, 26.50±3.18µ/L, 14.50±2.02µ/L and 9.80±1.44 µ/L, respectively. Statistically, there were significant difference (p<0.05) across the concentrations. Mean separation showed that the significant variations that occurred were from 0.00 mg/L and 4.30 mg/L. At 0.00 mg/L, 4.20 mg/L, 6.30 mg/L and 8.40 mg/L the concentration of alanine aminotransferase in the muscle were 17.00±1.75µ /L, 8.50±0.87µ/L, 21.00±2.89µ/L and 5.50±0.87 µ/L. Pairwise comparison reviewed no significant variations between 0.00 mg/L and 6.30 mg/L, and between 4.20 mg/L and 8.40 mg/L. On comparative analysis, the concentrations of alanine aminotransferase in the liver and muscle were significant different (p<0.05) at 0.00 mg/L and 4.20 mg/L. In addition, there was no significant difference (p>0.05) at 0.630 mg/L and 8.40 mg/L (Table 2).

The levels of the alanine aminotransferase across the various concentrations of the toxicant (Aluminum phosphide) decreased in the muscle and liver of adult Parophiocephalus obscurus except the muscle at 6.30mg/L that showed significant elevation. This is an indication of the adverse effects of Aluminum phosphide on the concentration of aspartate aminotransferase in the liver and muscle Parophiocephalus obscurus. The trend observed in this study is in line with previously works on chemical toxicity to aquatic organisms 7816. Like Aspartate aminotransferase, alanine aminotransferase is an important parameter used in determining the working condition of the liver. Alanine aminotransferase is an important enzyme that is found in liver, muscle and kidney of organisms that contribute in the breakdown of proteins in the body of several organisms. In addition, the alanine aminotransferase helps the liver to filter toxic substances from blood, store some nutrientsand bile production. Most of the alanine aminotransferase that is produced in the liver are stored there, and where the liver is damaged they will be released into the blood. Therefore, significant elevation in the alanine aminotransferase concentration of the liver and muscle of Parophiocephalus obscurus exposed to Aluminum phosphide suggests the effect of toxicity of the xenobiotics on the probe organisms. Based on the comparative assessment of the concentration of alanine aminotransferase in the liver and muscle of Parophiocephalus obscurus, it can be deduced that the liver accumulates more alanine aminotransferase than the muscle. This may be attributed to the role of liver alanine aminotransferase in breakdown of protein, storage of nutrients and filtration of toxic substances.

This study evaluated the impact of aluminum phosphide on the transferases of muscles and liver of Parophiocephalus obscurus. The investigation showed that aluminum phosphide initiates critical alteration on the transferases (alanine aminotransferase and aspartate aminotransferase) in the liver and muscle of Parophiocephalus obscurus. The impacts >0.00 to 8.00 mg/L of aluminum phosphide could be detrimental to the exposed organisms. The impact could be enhanced if the concentration of the toxicant increased. Hence there is compulsory to be cautious during the use of aluminum phosphide near biological system.