Occupational health issues are typically ignored by the vast majority of workers and businesses operating in developing countries, especially for those issues where exposure to toxins may take years to exhibit symptoms. There are multiple reasons for this, including behavioural, cultural and socio-economic. Regardless of the reason, the result is the same – workers are being exposed unnecessarily to toxins that are making them ill and in some cases resulting in long-term disability and death. Most disturbing is that the issues are well know and exposure can be easily controlled with little additional cost to the operation.
Lead exposure has been well documented recently because of the issue of lead piping in water supply of Flint, Michigan. This is of course nothing new. Some of us are old enough to remember the controversy over lead content in gasoline and paints; the phasing out of lead in gasoline and leaded paints starting in the 1970s. In fact, the issue of lead poisoning was documented as early as the 2nd Century BC in Greece.
Given the long-term and wide-spread understanding of the serious health issues associated with lead, the obvious question is why is lead still being used and how can we protect workers from excessive exposure?
To answer these questions, I will first review the health effects associated with exposure to lead, discuss uses for lead, describe where lead may be encountered and identify who is most at risk, and finally provide suggestions as to what HSE personnel can do to minimize worker exposure to lead.
What are the Health Effects Associated with Lead Exposure?
Lead is a toxic metal whose widespread use has caused extensive environmental contamination and health problems in many parts of the world. It is a cumulative toxicant that affects multiple body systems, including the neurologic, hematologic, gastrointestinal, cardiovascular, and renal systems. Children are particularly vulnerable to the neurotoxic effects of lead, and even relatively low levels of exposure can cause serious and in some cases irreversible neurological damage.
Lead is most commonly absorbed into the body by inhalation. When workers breathe in lead as a dust, fume, or mist, their lungs and upper respiratory tract absorb it into the body. They can also absorb lead through the digestive system if it enters the mouth and is ingested1.
A significant portion of the lead inhaled or ingested gets into the bloodstream where it circulates through the body and is stored in various organs and body tissues. Some of this lead is filtered out of the body quickly and excreted, but some remains in the blood and tissues. As exposure continues, the amount stored will increase if the body absorbs more lead than it excretes. The lead stored in the tissue can slowly cause irreversible damage, first to individual cells, then to organs and whole body systems2.
Chronic exposure resulting in blood lead levels (BLL) as low as 10 µg/dL in adults are associated with impaired kidney function, high blood pressure, nervous system and neurobehavioral effects, cognitive dysfunction later in life, and subtle cognitive effects attributed to prenatal exposure. Chronic exposures above 20 µg/dL can cause subclinical effects on cognitive functions as well as adverse effects on sperm/semen quality and delayed conception, and effects such as cognitive aging as well as deficits in visuomotor dexterity, lower reaction times and attention deficit. At BBLs above 40 µg/dL, workers begin to experience symptoms such as headache, fatigue, sleep disturbance, joint pain, myalgia, anorexia, and constipation. Finally, health effects at BLL over 60 µg/dL can range from acute effects such as convulsions, coma, and in some cases, death, to more chronic conditions such as anemia, peripheral neuropathy, interstitial kidney fibrosis, and severe abdominal cramping3.
Why is Lead Still Being Used?
Given these well-known and studied health effects, why then is lead still common in the workplace today?
Obviously, because it has significant benefits that apparently outweigh the deleterious impacts on health. In particular, due to its abundance, low cost and physical properties (low melting point, corrosion resistance, waterproof nature and malleability) lead and lead compounds have been utilized in a variety of products including4:
- ammunition & fishing sinkers
- paint & varnish
- ceramic glaze, glass & crystal pipes
- faucets & solders
- caulking & oakum
- x-ray shielding
- cable covers
- metal flashing
- tank liners
- brass, bronze & pewter alloys
- cosmetics & hair dyes (India)
- imitation pearls
- crayons (China)
The vast majority of lead consumption today is for lead-acid batteries and other significant uses of lead are in ammunition, oxides in glass and ceramics, casting metals, and sheet lead5. China is by far the largest producer and consumer of lead worldwide6.
Who Is At Risk?
In construction, lead is used frequently for roofs, cornices, tank linings, and electrical conduits. In plumbing, soft solder, used chiefly for soldering tinplate and copper pipe joints, is an alloy of lead and tin. Because lead-based paint inhibits the rusting and corrosion of iron and steel, lead continues to be used on bridges, railways, ships, lighthouses, and other steel structures. Leaded paint is also still common across much of Asia7.
Workers in the lead smelting, refining, and manufacturing industries experience the highest and most prolonged occupational exposures to lead8. Increased risk for occupational lead exposure also occurs among workers associated with:
- battery manufacturing plants
- rubber products and plastics industries
- steel welding/cutting operations
- other manufacturing industries
- bridge maintenance and repair workers
- municipal waste incinerator workers
- people who work with lead solder
- radiator repair mechanics
- pottery/ceramics industry employees
It is also important to note that occupational exposures can result in secondary exposure for workers’ families if workers bring home lead-contaminated dust on their skin, clothes, or shoes or if parents work in these industries and allow their children to visit them at work.
How to Minimize Exposure to Workers?
There are two main ways lead can enter the body – inhalation and ingestion. Lead may be inhaled when it is burned or melted releasing some of the lead as a fume. Lead may also be inhaled when dust that contains lead becomes airborne.
Recognition of the potential sources of lead and application of effective control measures to limit release of fumes and dust to the work environment coupled with appropriate PPE and management programs can virtually eliminate risks associated with workplace lead exposure, for instance9:
- Engineering controls – Engineering measures include local and general exhaust ventilation, process and equipment modification, material substitution, component replacement, and isolation or automation.
- Housekeeping and Personal Hygiene – A rigorous housekeeping program and the observance of basic personal hygiene practices will minimize employee exposure to lead. In addition, these two elements of the worker protection program help prevent workers from taking lead-contaminated dust out of the worksite and into their homes where it can extend the workers’ exposures and potentially affect their families’ health.
- Protective Clothing and Equipment – Appropriate and clean protective work clothing and equipment includes: coveralls or other full-body work clothing; gloves, hats, and shoes or disposable shoe coverlets; vented goggles or face shields with protective spectacles or goggles; welding or abrasive blasting helmets; and respirators.
- Employee Information and Training – Inform employees about lead hazards according to pertinent local and/or international requirement including but not limited to the requirements for warning signs and labels and material safety data sheets (MSDSs).
- Medical Surveillance Programs – These should be implemented for those working directly with lead or are employed in a lead-related industry, with a focus on monitoring BLL.
Most of these protective measures can be implemented at minimal cost to your business and will provide long-term benefits to the workforce. Take some time, understand the issues of these toxic compounds and your worker’s and their families will benefit.
Thanks for reading. Keep safe. Be healthy. Respect your environment.
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- Lim S., T. Murphy, K. Wilson and K.N. Irvine. 2015. Leaded Paint in Cambodia—Pilot-scale Assessment. J. Health & Poll. 5(9): 18-24. http://www.researchgate.net/publication/287647777