The study and application of health risk assessment techniques are crucial in order to understand the risk of exposure to heavy metals and other harmful pollutants. It entails evaluating the risks of exposure at various concentrations and with reference to certain standard values approved by World Health Organization (WHO) and United States Environmental Protection Agency (USEPA). Investigation of water contamination with heavy metals has become the prime focus of environmental scientists in recent years. Effluent discharges into aquatic system affect living organisms within the receiving environment. The concentrations of these metals were mostly assessed at 50th, 75th and 95th percentile and various exposure evaluated. This review covers studies in water, air, soil and fish samples. Air risks assessment was not given the needed attention and children were more susceptible to the hazard than adult, especially lead toxicity, resulting in health complications. Heavy metals bio accumulates over time, and lethal upon exposure at low concentrations. This review will assist risk managers to minimize the exposure at optimum level as well as for the government to formulate policies in safe guarding the health of population.

The present study assessed the role of larvicidal activities of hexane, ethyl acetate and methanol dried leaf and bark extracts of Ocimum gratissimum, Gleditsia triacanthos, Eucalyptus sglobulus and Azadirachta aindica against the fourth instar larvae of filariasis vector, Culex quinquefasciatus mosquito (Diptera: Culicidae). Larvicidal activities of four medicinal plant extracts were studied in the range of 4.69 to 1000 mg/l in the laboratory bioassays against early 4th instar larvae of Culex quinquefasciatus. The mortality data were subjected to probit analysis to determine the lethal concentrations (LC50 and LC90) to kill 50 and 90 per cent of the treated larvae of the respective species. All plant extracts showed moderate effects after 24 h of exposure; however, the highest toxic effect of leaf methanol extract of Ocimum gratissimum, bark ethyl acetate extract of Eucalyptus globulus, methanol extract of Azadirachta indicia and methanol bark extract of Gleditsia triacanthos against the larvae of Culex quinquefasciatus with LC50=43.00, 41.02, 40.12 and 20.36 mg/l; LC90=278.32, 218.72, 215.01 and 86.29 mg/l respectively. The result of findings shows that leaf and bark extract of G. tricantha, A .indica, O. gratissimum and E .globulus can be developed as ecofriendly larvicides.

Mosquito control has become more difficult due to the unsystematic use of synthetic chemical insecticides which have inauspicious effect on the environment. Botanical phyto-chemicals with mosquitocidal potential are now recognized as potent alternative insecticides to replace synthetic insecticides in mosquito control programs due to their excellent larvacidal activities. The present study assessed the influence of A. sativum (garlic), Z. officinale (ginger) and S. aromatic (clove) extracts against Aedes mosquitoes. Larvacidal activities of three indigenous plant extracts were studied in the range 5.0 to 30.0mg/l in the laboratory bioassay against fourth instar larvae of Aedes sp. The mortality were subjected to probit analysis to determine the lethal concentration (LC50) to kill 50 percent of treated larvae of Aedes sp. Data obtained were analyzed by Comparing experimental groups and control groups with significance level established at p<0.05. All plants tasted showed effects after 24hrs of exposure at different concentration (mg/l). However the highest mortality was found in A. Sativum (garlic) and Z. officinale (ginger) against larvae of Aedes mosquitoes with LC50 = 42.50% (2.685) and LC50 = 30.01% (4.461) mg/l, while S. aromatic(clove) was found to have lowest mortality at LC50 = 24.50% (5.52) respectively. It is therefore recommended that A. sativum(Gallic), S. aromatic (Clove) has showed larvacidal effects against Aedes mosquitoes and could be served as alternative form of botanical control against mosquitoes . Keywords: A. sativum (garlic), Z. officinale (ginger) and S. aromatic (clove), Extracts, Aedes mosquitoes

The study was aimed at finding the effectiveness of a physical method of controlling filariasis vector larvae. Four ovillanta traps were placed in four different sites (north, south, west and east) of Gwale Local Government area of Kano state. The eggs and immature stage(larvae) of the filariasis vector were collected and destroyed. A total of 134667 larvae were collected altogether. 25% from site A, 23% from site B, 28% from site C and 24% from site D.The finding of the study shows that ovillanta trap is an effective method in controlling filariasis vector.

The study is carried out to standardize larval indices namely House Index, Container Index and Breteau Index and also to identify the major breeding sources of mosquitoes in the residential environment in and around the Gwale Local government area of  Kano, Nigeria. A cross-sectional study by selecting 50 houses randomly from the 6 wards of Municipality was employed. Every water holding container indoors and outdoors were counted and searched for larval presence and noted on a pretested format. In this study, 300 houses were surveyed in 21 days out of which 94.33% (283 houses) were found to have potential sources for mosquito breeding. All the entomological indices were found to be above the critical level. House Index = 28.67%; Container Index = 12.14%; Breteau Index = 64.00% showing high chances for outbreaks of mosquito borne diseases. The area is prone to mosquito borne disease like malaria and therefore warrants interventions from the competent.