Introduction: Lead and Society
Lead has been an environmental concern since it’s toxic effects were first recorded in ancient Greece (1). The metallurgic characteristics of lead are extremely attractive: it is entirely malleable (easily shaped), it conducts electricity, it is resistant to corrosion, it is incredibly dense, and has been readily available in developed societies, including ancient Greece and the modern day global marketplace.
Environmental lead awareness has been in full swing in the United States for over 30 years, and has generally been a step behind the governments in Europe at enacting legislation (2). Today with the advent of the internet and more globally occurring business markets than ever, legislation in the European Union has caused a reevaluation of the manufacturing of consumer electronics in the US.
This article explores the issue of lead in electronics, and to get an insider’s view of the issue I have talked with an engineer working in the electronics manufacturing industry with over 30 years’ experience, and he gave me his observations on the issue.
The Restriction of Hazardous Substances Directive
To understand the overarching issue let’s take a quick look at the Restriction of Hazardous Substances (RoHS) directive by the European Union. The EU tends to stay ahead of the US in environmental legislation. They also banned the use of lead in paint just before the United States (3), and there are certain substances such as BPA (see my article on Household Endocrine Disruptors) that the EU has begun to phase out of certain products while the US lags.
RoHS is directed at electronic equipment and its toxic components. Six compounds: Lead, Mercury, Cadmium, Hexavalent Chromium and two flame retardant compounds: PBB and PBDE. Lead is the material that causes the most controversy among engineers, however, due to its primary use in electronics, which is in the tin-lead alloy used for solder.
While the RoHS directive is only a legal requirement in European markets, enforcing it there means that all products for sale on those markets have to adhere to the legislation. American companies, aware of the huge European market at risk, have already modified their processes to comply, and are continuing to refine them for maximum efficiency.
The Pros of Removing Lead from Solder
The main benefits of the directive are environmental, and deal with the fact that Lead is a toxic and harmful metal. This fact has been established for about 2000 years at this point and societies have been trying to deal with it since (1).
Lead has been removed from piping, paint, gasoline, and food containers to prevent effects on human health. Lead still exists in large quantities in the general market today in the form of car batteries, ammunition, weights for balancing car tires, and leaded glass crystal. Areas with high concentrations of lead in our modern society include areas with a lot of large industry or a history of such, and areas along major roads more than 20 years old.
A major reduction of lead in landfills could be accomplished in a perfect world by systematically finding replacements or alternatives for the major products and processes that use lead, such as electronics. This is desirable due to the reduction in health risks. According to a study published in the engineering journal JOM, lead at various levels can reduce the IQ score of children by as much as 5 points, raise systolic blood pressure in adult males, and also cause Anemia (low blood iron levels) (4).
The Cons of Removing Lead from Solder
In electronics, however, lead is a vital component. The tin-lead alloy used for solder in modern electronics is the foundation upon which much of the industry was designed, according to a systems engineer who agreed to talk with me about this issue.
In the electronics industry those with enough experience to understand the full impact of this legislation are concerned about its overall efficiency. My source discussed his worries that energy and quality issues introduced by the requirements will outweigh their environmental benefits. He discussed the following points with me:
Non-leaded solders like SAC (Tin, Silver, and Copper) have a higher melting point that leaded solder and heating large quantities of them will require huge energy demands by electronics manufacturers. This energy demand is likely to cause an increase in pollution of other kinds while we still live in an oil-dependent society.
Unleaded tin solder has issues of its own besides melting point. Lead in the alloy helps to prevent the appearance of “Tin Whiskers”. These whiskers are a natural phenomenon that occurs in tin, where small, hair-like projections will grow perpendicularly from the surface of the tin component. These have been known to cause damage, and electrical malfunction. Although it has not been proven that they played any part in the incident, tin whiskers were also found in some of the malfunctioning Toyota car models that accelerated uncontrollably.
The last major problem is the cost for these modifications. The SAC compound is significantly more expensive to manufacture than leaded solder, and the process modifications to a major manufacturing facility are staggeringly expensive.
All that extra expense is to be made up by the consumer. On top of that the new processes are certain to set back the quality assurance capabilities of these companies as they attempt to accumulate data on their new products, possibly leading to reduced performance, durability, and longevity. The consumer may end up paying more for an inferior product in order to eliminate lead.
For these reasons the directive does not apply to ‘mission critical’ components in aerospace shuttles, life sustaining medical equipment, and military equipment. Components that cannot afford to fail may be exempt, but unforeseen dangers and problems are still likely to arise.
Conclusion: Evironmetal Benefit Vs. Quality and Monetary Cost
My source pointed out that while reducing lead in the environment is a great idea, other strategies might be more practical for removing it. For example according to his research in 2006, he found that globally:(approximately) 4 million tons of lead was used in batteries, 200,000 tons were used in ammo, 100,000 tons were used in tire balancing weights, and 18,000 tons were used to manufacture electronics.
Overall this gives the result that roughly 0.4% of the lead used in materials for sale was from electronics, and yet 100% makes it into the environment. Restricting other products could be more efficient and safer.
References
1.) Pearce, JM (2007). "Burton's line in lead poisoning.". European neurology 57 (2): 118–9.
2.) Rossi, E (2008). "Low level environmental lead exposure--a continuing challenge.". The Clinical biochemist. Reviews / Australian Association of Clinical Biochemists 29 (2): 63–70.
3.) Gilbert, SG; Weiss, B (2006). "A rationale for lowering the blood lead action level from 10 to 2 microg/dL.". Neurotoxicology 27 (5): 693–701.
4.) Ogunseitan, Oladele. "Public Health and Environmental Benefits of Adopting Lead-free Solders." JOM 59.7 (2007): 12-17. Public Health and Environmental Benefits of Adopting Lead-free Solders. Web. 16 Mar. 2011
Terry Petano - Welcome to my writer profile, I'm a college graduate with a major in Biology and a minor in Math. I work in the biotechnology industry, ...
