I read some few reports and studies on Arsenic poisoning and then started wondering on how safe are our poultry products as well as the water we consume here in Nigeria. This thought came to my mind because of the fact that Nigeria is a developing economy with questionable safety standards especially when it comes to the issue of environmental safety.
I would like to summarily say something on Arsenic to be able to have a good understanding of it. Arsenic, a metalloid, is considered a poisonous substance released both from certain human activities and naturally from the Earth’s crust. It is widely distributed in the earth’s crust and present at an average concentration of 2 mg/kg. It is basically found in two forms:
1. Inorganic arsenic mainly found in groundwater used as drinking water in several parts of the world, eg Bangladesh, India and Taiwan.
2. Organic arsenic (compounds contains carbon) are mainly found in sea creatures some species living on land.
Arsenic compounds occur in crystalline, powder, amorphous or vitreous forms and are found in trace quantities in all rocks, soil, water and air, the concentrations of which may be higher in certain areas as a result of weathering and anthropogenic activities eg smelting, mining, use of fossil fuel and pesticide.
Humans are exposed to arsenic mainly through food and water, particularly in certain areas where the groundwater is in contact with arsenic-containing minerals.
Man made sources of the world environmental arsenic production has been estimated as follows: about 70% in the preservation of timber, 22% in agricultural chemicals/pesticides and the remainder in pharmaceutical products, glass and non-ferrous alloys. Of these, mining, smelting of non-ferrous metals and burning of fossil fuels are the major industrial processes that contribute to anthropogenic arsenic contamination of air, water and soil.
There are various techniques in use for the detection as well as determination of arsenic level and these includes:
• test kit based on the colour reaction of arsine with mercuric bromide is currently used for groundwater testing in Bangladesh with a detection limit of 50–100 µg/litre under field conditions
• atomic absorption spectrometry (AAS)
• inductively coupled plasma atomic emission spectrometry (ICP-AES)
In the body, arsenic can be estimated by taking samples of blood, urine, hair, or nails and measuring the arsenic (or its bi-products) present. Serum level of arsenic indicates recent high exposures eg acute poisoning or long term exposure, as it is rapidly cleared from blood, urine samples measures recent exposure and levels in hair and nails indicates past exposure.
Human exposure to arsenic is mainly through food (largest source) and water. Other sources include air (high quantities inhaled by smokers because arsenic is one of many hundreds of chemicals present in cigarette smoke). Once ingested or inhaled, they rapidly get absorbed into the blood stream, transformed and eliminated from the body via the urine (which is partly dependent on intrinsic properties of individuals).
As set by the WHO and IARC, Internationally acceptable value of arsenic in drinking water is 10 µg/litre and any amount above this is considered as harmful to the human system.
It was mentioned in a study published in ‘Environmental Health Perspectives’ (Volume 116, number 4, 2008) that since 1960s, it has become a common practice adding small amounts of inorganic arsenic compounds in poultry feeds; this is in an attempt to get a good yield by speeding up the growth of chickens and other birds, killing certain bacteria in them and also making their breast meat pinker. This practice is often seen in large-scale poultry producers to be able to make a good profit out of sale of their products.
Although harmful to humans when it exceeds a recommended amount, use of inorganic arsenic has been decreed by the USDA that it is safe when used in an amount that its concentration in poultry meat doesn’t exceed 0.5 parts per million. This generated a question in the minds of several public health specialists: “Is this practice safe to humans?” Several studies that followed this question showed that chronic exposure to high levels of arsenic has been linked to several medical conditions which include: cancer, heart disease, diabetes and a decline in brain function. It is as a result of these studies that in 1999, the EU banned use of arsenic in poultry production with several U.S. poultry industries following suit out of will.
In another report which I also read with a caption “Arsenic sinks to new depths”, in Southern Asia, especially the Bengal Basin, groundwater overuse can push the poisonous arsenic deeper as seen in Vietnam which has a record of over a century of groundwater over exploitation that pushed the water level further down carrying arsenic with it. Thus drinking arsenic-laced water (as well as water from deeper wells) can lead to a range of health problems, as mentioned earlier. It was thought initially that deeper aquifers are arsenic-free in these countries, some municipal authorities in Bangladesh, and many in Vietnam, are drilling into lower sediments.
1. Environmental Health Perspectives, Volume 116, number 4, 2008
2. Arsenic sinks to new depths (http://www.nature.com/news/2011/110117/full/news.2011.20.html)
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