What some are calling the largest mass poisoning in history is happening literally under our feet! According to researchers from the University of California and Linkoping University, Sweden, “Bangladesh is grappling with the largest mass poisoning of a population in history because groundwater used for drinking has been contaminated with naturally occurring inorganic arsenic. It is estimated that of the 125 million inhabitants of Bangladesh between 35 million and 77 million are at risk of drinking contaminated water.”1 West Bengal (India) has similarly serious arsenic issues as does Cambodia and Vietnam; areas of Afghanistan, China, Indonesia, Inner Mongolia, Laos, Myanmar, Nepal, Pakistan Philippines, and Taiwan are also affected. 2
In this blog post I am switching gears a bit and focusing on an issue that is primarily a public health rather than an occupational health concern. But given the scale of this issue across Asia and the serious health consequences of exposure, I strongly believe this is an issue for which all HSE professional should be aware.
Why Should HSE Practitioners Be Concerned about Arsenic?
First, while many of the readers of my blog post come from a safety background, let’s not forget that the H in HSE stands for Health and the E stands for Environment. Educating yourself on important topics outside of your particular areas of expertise expands your knowledge-base, which is important as you grow in your profession.
Second, if you live and/or work in one of the countries affected by arsenic poisoning, then you owe it to yourself, your family, your neighbours and your colleagues to be aware of this issue and to find solutions to protect against exposure from drinking arsenic-contaminated water and/or eating arsenic-contaminated food.
Third, there are also specific occupational health issues related to arsenic exposure in the workplace. While these workplace exposures are not as common as the public health crisis noted above, such exposures can and do pose a significant health risk to some workers.
Hopefully you are convinced this is an important HSE issue and you are still reading! In the remainder of the post I’ll provide a brief overview of arsenic, a discussion of health impacts of arsenic exposure, uses of arsenic and exposure by workers, and how to minimize exposure of workers and others to this toxic compound.
What is Arsenic?
As noted by McCarty et al (2011)2, arsenic is ubiquitous in the environment as a result of geological contributions and anthropogenic (man-made) sources.
Arsenic is widely distributed in the earth’s crust and commonly associated with metal sulfide ores, and can also be found in many oxide minerals and hydrous metal oxides. As a result, the natural weathering of rocks and minerals appears to be a major source of arsenic found in soils and groundwater. The nature of arsenic in soil is controlled by the lithology of the parent rock materials, volcanic activity, weathering history, transport, sorption, biological activity, and precipitation. Elevated concentrations of arsenic in groundwater derive directly from reductive dissolution of iron oxyhydroxides, which naturally occur in aquifers.
Human activities considered to be the sources of arsenic contamination include mining, metal smelting, fossil fuels combustion, waste incineration, irrigation, application of pesticides, herbicides, and fungicides, crop desiccants, wood preservatives, and food additives for cattle and poultry.
Levels of Arsenic in the Environment2
The guideline value for inorganic arsenic in drinking water was reduced from 50 μg/L to 10 μg/L by the World Health Organization (WHO) in 1993. Nonetheless, many countries, particularly developing countries, still use the 50 μg/L value as standard for arsenic partially because of lack of adequate analytical instruments for lower arsenic concentrations in water.
Elevated concentrations of arsenic in drinking water (above 50 μg/L) have been reported in several countries, including Argentina, Chile, China, Mongolia, Taiwan, Nepal, Japan, Mexico, Poland, Vietnam, and the USA. Local-scale problems of arsenic contamination of groundwater have been reported by some countries, and new cases are continually discovered – groundwater contaminated by arsenic can be found all over the world.
To date, the globally worst-affected areas are located in Bangladesh and West Bengal (India), where arsenic in groundwater has been documented at concentrations up to 3,200 μg/L. Moreover, in some districts of this affected area, more than 90% of tube wells were contaminated by arsenic. Inorganic arsenic concentrations in the Red River Delta of northern Vietnam have been reported between 1 and 3,050 μg/L and averaged 159 μg/L, approximately 15 times higher than the recommended value for arsenic in drinking water. Groundwater samples from the Upper Mekong River Basin in Cambodia displayed rather wide ranges of arsenic up to 855 μg/L for groundwater in Kandal province and up to 1,340 μg/L for groundwater restricted to Bassac and Mekong River. An arsenic concentration range of <0.1–1,351 μg/L was also reported for the Lower Mekong Delta in Vietnam.
Arable land can be contaminated by irrigation using arsenic-rich groundwater. For example, it is estimated that between 900,000 and 1,360,000 kg arsenic per year was introduced into Bangladesh soil through contaminated groundwater used for irrigation.
What are the Health Effects Associated with Arsenic Exposure?
For the general public, arsenic can poison people by direct ingestion of contaminated drinking water and contaminated foods and by absorbing it through the skin from bathing and washing with contaminated water.
For workers, there are also pathways related to breathing in arsenic-contaminated dust or fumes; absorbing it through the skin, and/or swallowing it, after handling food when workers have residual arsenic dust or arsenic compounds on their hands.
As noted by the UK’s HSE, arsenic has both short-term and long-term effects on human health.
Short-term effects can include:
- irritation of the eyes and nose
- skin damage and inflammation
- stomach upsets
- in more severe instances, internal bleeding from the stomach and intestines (in extreme cases, this can lead to death)
Longer-term effects can include:
- damage to the inside of the nose
- skin colour changes and prolonged skin inflammation problems
- inflammation of the lungs
- damage to peripheral nerves, with numbness and loss of vibration sense in particular
- problems with the heart and heart rate/rhythm
It is important to note that repeated exposure to arsenic and arsenic compounds over a long time can cause cancer, particularly in the lungs, skin and liver.
Industrial Uses of Arsenic
According to ASTDR, in 2003, the world’s largest producer of arsenic compounds was China; the United States was the world’s largest consumer of arsenic. In the past, the United States primarily used arsenic in insecticides such as ant killers and animal dips (the concentrated liquid forms of these are most toxic to humans). However, regulatory restrictions for arsenic, especially for home products, have reduced its use and should also reduced the exposure risk to it in the USA (but not in many developing countries!).
Other sources include
- algaecides
- desiccants used in mechanical cotton harvesting
- glass manufacturing
- herbicides (such as weed killers for telephone and railroad posts and Agent Blue, which was used by U.S. troops in Vietnam)
- nonferrous alloys [Garcia-Vargas and Cebrian 1996]
Arsenic trioxide may be found in pesticides and defoliants.
Presently, arsenic is widely used in the electronics industry in the form of gallium arsenide and arsine gas as components in semiconductor devices.
Production of wood preservatives, primarily copper chromated arsenate (CCA), accounted for more than 90% of US consumption of arsenic trioxide in 2003. This is no longer widely used in the US but of course remains a problem in many developing countries.
How to Minimize Exposure to Workers?
The UK’s HSE provides solid advice for managing arsenic exposure in the workplace:
- assess the risks to your health and identify the precautions needed for your protection
- protect against being exposed to arsenic and its compounds, or where this cannot reasonably be done, adequately control your exposure
- reduce your exposure to arsenic and its compounds so far as reasonably practicable, and ensure exposure is always below 0.1 milligrams per cubic metre of air averaged over an 8-hour period, in accordance with the workplace exposure limit (WEL) assigned for arsenic and its compounds
- maintain all fume and dust extraction controls in efficient working order
- find out how much arsenic workers are exposed to, normally through a monitoring programme, and inform the workers of the results
- arrange any health checks that are needed
- inform, instruct and train all employees who may be exposed to arsenic and its compounds
If you are an HSE officer where arsenic is a potential issue, but you do not have sufficient budget for monitoring arsenic levels, then assume that your workers are at risk and make sure employees:
- use the extraction equipment or other control measures correctly
- use the protective clothing and equipment provided
- always use the washing facilities provided, which should be adequate and suitable for your needs
- report defects in enclosures, extraction equipment or other control measures to your employers
- don’t eat or drink in work areas where arsenic or arsenic compounds may be present
Note that most of these protective measures can be implemented at minimal cost to your business and will provide long-term benefits to the workforce.
What About Exposure to Arsenic-Contaminated Drinking Water and Food?
Of course, if you are managing a facility where the drinking water and food are contaminated with arsenic, then you, your colleagues and your families and friends can be exposed to dangerously high levels of arsenic regardless of whether your facility has work-related arsenic issues and/or if your facility makes use of sound preventative arsenic exposure control measures.
What can you do about this issue?
First and foremost, do not sit on your hands and do nothing! While this is a huge problem you can make a difference. I suggest the following and I know readers will have other valuable suggestions:
- Understand the situation where you live and work. There are multiple resources on line and via local environmental and public health institutes. Check these out and determine whether or not you have a problem where you live and/or work.
- Be ware of the signs of chromic arsenic exposure. The most obvious signs are probably related to skin darkening (hyperpigmentation), formation of scaly skin on the palms and soles (arsenical keratosis) and exfoliative dermatitis.
- Minimize exposure. The most direct exposure routes that cause the most serious health effects are from drinking contaminated water and eating contaminated food. Treat water or find alternative sources of water and food if these are suspected.
- Get involved. Tell others! Be proactive and educate others in your community. There are many programs for alternative water sources and even technology to remove arsenic. Don’t wait for others to solve this problem for you – be a leader.
Finally, I would like to thank one of the blog readers, SB, who is researching this issue now as part of a Masters program in Pakistan. Good luck to you in your research.
Thanks for reading. Keep safe. Be healthy. Respect your environment.
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Next Week’s Blog Topic: The Challenge of E-Waste Management in Developing Countries
Photo Credits: Arsenic image courtesy of Creative Commons Attribution-NonCommercial-NoDerivatives licence.
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