Total petroleum hydrocarbons in soil and water, heavy metal concentration in water and related health symptoms among fuel station’s workers in Dar es salaam, Tanzania

Abstract

Background: Petroleum hydrocarbons and heavy metals can be found in both soil and water. Petroleum hydrocarbons are complex substances formed from hydrogen and carbon molecules sometimes containing other impurities such as oxygen, sulphur, and nitrogen; while heavy metals are metallic chemical element commonly found in contaminated soils, is characterized by having relatively high density and is toxic or poisonous at low concentrations. Petroleum hydrocarbons and heavy metals found in petroleum and other materials, are known to cause various detrimental health conditions including dizziness, loss of consciousness, vomiting, headache and skin, lung or eye irritation. There is a noticeable growing number of fuel stations in Tanzania especially in the city Dar es salaam. Little is known about petroleum hydrocarbon in waters and soil, heavy metal concentration in the soil and also its associated health symptoms among fuel station workers in Tanzania. Objective of the study: To assess total petroleum hydrocarbons in soil and water and heavy metal concentrations in water and related health symptoms among fuel station workers in Dar es Salaam. Materials and Methods: A quantitative cross section study was conducted at fuel stations U, V, W, X and Y at Ilala Kinondoni and Temeke in Dar es Salaam, Tanzania. Soil samples were obtained during drilling works using a Geomash PB U-2 rig. Samples were taken every half a meter and three samples with highest volatile organic compounds detected by photo ionization detector were taken to the laboratory for analysis of petroleum hydrocarbons. Water samples were obtained using a An Eijkelkamp 12 VDL peristaltic pump was used in obtaining water samples, together with the Geotech Interface meter (Model 122-P8-LM3-30M) and YSI (Yellow Springs Instruments) parameter meter. Obtaining of the samples was depending on the depth of the well and water level. Laboratory analysis method of samples for petroleum hydrocarbons was done by gas chromatograph method and laboratory analysis of petroleum related heavy metals in water samples was done using Inductively coupled Plasma Mass Spectrometer series 2. The study also interviewed 25 respondents from fuel stations to determine whether fuel station workers wear personal protective equipment when at work and whether they had experienced any related health symptoms as a result to exposure to petroleum hydrocarbons and petroleum related heavy metals using both questionnaires and observation. Results were presented in a reporting form based on the findings from questionnaires done during field work. Sample Analysis: Laboratory analysis by gas chromatograph analysis method was used to analyse both water and soil samples for different petroleum hydrocarbons in water and soil at fuel stations. Data was produced with an Agilent Chemstation chromatography software version 10. Analysis of heavy metals concentration in water samples was done using Inductively Coupled Plasma Mass Spectrometer series 2 based on the ionization of analytes in water sample, separation, and detection the ions for determination of metal concentration. Related health symptoms among fuel station workers were presented in a reporting form based on the findings from questionnaires done during field work. Results: The study findings revealed petroleum hydrocarbons concentration in fuel stations U, V, W, X, and Y were 417 mg/kg, 644.33 mg/kg, 1488.33 mg/kg 135.33 mg/kg and 129.97mg/kg respectively. These concentrations were high compared to the accepted threshold limit of 100mg/kg according to World Health Organisation standards. Highest petroleum hydrocarbon concentration in water was found at fuel station Y having a concentration of 9040ug/l. Comparing with the World Health Organisation threshold limit of 100ug/l, this concentration was relatively high. Petroleum hydrocarbons related heavy metals concentration such as Lead were found to be 31ug/l which is also above the World Health Organisation acceptable threshold limit of 15ug/l. Mercury concentration was found to be 0.2ug/l which was within the World Health Organisation accepted limit level of 2ug/l. The study found that 40% of fuel station workers were not wearing protective equipment such as mask. This was due to lack of equipment as well inadequate knowledge on harmful effects of petroleum hydrocarbons among workers. Health symptoms associated with petroleum hydrocarbons to petrol station attendants includes nausea, vomiting, and redness of the eyes. The findings from this study indicates existence of health symptoms which was influenced by petroleum hydrocarbons at fuel stations. Conclusion: Total petroleum hydrocarbon concentrations in the soil and water were above the recommended World Health Organization threshold limit, This study also indicates the heavy metal concentration in water samples analysed such Lead to be higher while that of Mercury is significantly lower compared to threshold limit established by World Health Organization. This finding suggests that fuel station workers continue to be exposed to petroleum hydrocarbons and heavy metals that eventually can pose health concern among fuel station workers. The study found that most of fuel station workers were not wearing protective equipment when at work and that majority of fuel station workers did experience health problems related to exposure of petroleum hydrocarbons and petroleum related heavy metals at workplace