EHOs in the Niger Delta area must watch out for Benzene in underground water sources. Include Benzene in water analysis chemical parameters. Also to be on the watched list is ARSENIC in Drinking water.
All these could be made easier with the establishment of ENVIRONMENTAL HEALTH LABORATORY in all states in Nigeria especially the impacted states.
Benzene is a petroleum hydrocarbon and also a natural product. Benzene is a clear, colorless, aromatic, highly flammable liquid with a distinctive, sweet smell.
Benzene occurs naturally and evaporates easily. Small amounts are released by volcano eruptions, forest fires, and underground oil and gas reservoirs; however, larger amounts are released by human activities.
Benzene is a component of crude oil and petroleum-based chemicals that can be released into the environment through motor vehicle exhaust, leaking underground storage tanks and gasoline spills.
Benzene is also present in petroleum products used to manufacture such common products as plastics, nylon, Styrofoam, rubber, dry cleaning solvents, dyes, lubricants, printing fluids and pesticides.
Benzene may escape into the environment through industrial discharges, improper waste management and faulty product handling and storage. Tobacco smoke also releases benzene into the air.
WHAT BENZENE IS USED FOR:
It is a solvent and building block for many chemicals, including BTEX, styrene, detergents and cumene that is converted to phenol and acetone. The largest use is in gasoline as an octane enhancer, especially since the elimination of lead. Gasoline contains about one or two percent benzene and other aromatics.
HUMAN EXPOSURE:
Exposure occurs from occupations, airborne inhalation, traces in foods and alcoholic beverages and minimal amounts in some drinking water sources. Outdoor airborne levels average about 1 ppb and contribute around 7.5 µg/day.
Indoor air is greater with contributions from secondhand cigarette smoke, gas cooking, wood burning stoves and fireplaces, as well as releases from furnishings and attached garages, with levels as high as 31 µg/m3.Cigarette smoking is the single, greatest human exposure source. A cigarette smoker can inhale about 1.8 mg (1800 µg) per day directly from 32 cigarettes.Drinking water is a negligible source for the vast majority of people.
OCCURRENCE IN WATER:
Most surface and ground water contain no detectable benzene. However, Borehole (Well) water contaminated with gasoline from leaking underground storage tanks or a nearby hazardous waste site often contains some benzene. Oil spill and bunkering have contributed immensely to underground water pollution in the Niger Delta area especially.
Sadly water analysis is not mostly done by water source providers exposing the large populace to benzene poisoning as result of constantly consuming hydrocarbon contaminated water. Where water analysis is done, Benzene and arsenic are not usually part of the chemical parameters for analysis. Why?
Environmental Health Officers and professionals in the Niger Delta areas must start enforcement of Benzene and Arsenic inclusion in the chemicals parameters.
HEALTH EFFECTS:
As with most volatile solvents, benzene can cause drowsiness and headaches at high inhalation Levels. Benzene is a known human carcinogen — based upon occupational epidemiology.
Leukemias are the principal cancer concern. Lifetime risk calculation for inhalation is about one in 100,000 to one in one million for exposure at 1 µg/m3. The calculated risk of one in one million for ingestion through drinking water is between 10 and 100 ppb. The other BTEX hydrocarbons have much less chronic risk than benzene.
ANALYTICAL METHODS:
Analyses are by purge and trap gas chromatography and related procedures.
BENZENE CONTAMINATED WATER TREATMENT:
Granular activated carbon and aeration are available to water treatment plants. Reverse osmosis is not effective because an organic solvent, such as benzene, can dissolve in the membrane and migrate to the treated water.
POU and POE using activated carbon are effective, however, they must be replaced before exhaustion.
WHAT IS BENZENE?
Benzene is a hydrocarbon manufactured from petroleum and also a natural product in some foods. It is a six-member carbon ring with a hydrogen attached to each carbon. Benzene is the base product among the family of BTEX (benzene, toluene, ethylbenzene, xylene) hydrocarbons produced in very high volume. The other BTEX have a methyl group (CH3–), or ethyl (C2H5–) or two methyls attached to the benzene ring.Its boiling point is 80.1o C (176.2o F), and water solubility is about 2 grams per liter. Its molecular formula is C6H6, and its molecular weight is 78.11 daltons. It is called an aromatic hydrocarbon but that is more so a name of the family of chemical structures, rather than an odor indication. It is a VOC and lighter than water with a specific gravity of about 0.9 g/ml. The odor detection threshold is about 5 mg/m3.
REGULATION/ENFORCEMENT LIMITS :
The drinking water Maximum Contaminant Level Goal (MCLG) is zero, and the Maximum Contaminant Level (MCL) is 5 ppb.
The World Health Organization (WHO) drinking water guideline is 10 ppb.
All of these are very conservative values.
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