Product safety – Getting the LEAD out

What is lead?

Product Safety, Getting the Lead Out.

Lead is a natural compound and it can be very serious from a health perspective. It is a type of metal known as a heavy metal. Heavy metals have a high density and are toxic at low concentrations. In general, heavy metals are not required for proper functioning of the body and have no biological purpose¹. Their accumulation in the body, without effective removal, can lead to significant health problems.

History of lead

Lead was one of the first metals to be extracted from the Earth’s crust. It is an abundant element and easy to work with because it is soft and melts at low temperatures. Its durability was another reason that it was popular to work with, however this durability is one of the reasons that it became such a health issue². Lead has been used throughout history in a wide range of applications. Both the Chinese and Romans used lead to make coins, and the Romans even used lead in their wine making processes as it gave the wine a sweet taste. The Romans plumbing systems were composed predominantly of lead², and the chemical symbol for lead, Pb, comes from the latin Plumbum, referring to its use in these plumbing systems.

Lead has also been used extensively in the printing industry and the fuel sector. In 1921 General Motors engineers reported that, by adding tetraethyl lead to gasoline, it could create quieter operating engines and boost performance. Even though hundreds of workers would later be pronounced psychotic from lead poisoning, the practice of adding lead to gasoline continued for decades³. Standards for lead in fuel were eventually introduced in the 1970s and over the next 3 decades were eventually phased out. While unleaded fuel is the standard now in the US, Europe and developed countries, leaded fuel is still used in many developing countries.

Lead has also been used extensively in paint. Lead was added to paint for a range of functions⁴

• It provided a colour, depending on the type of lead
• It decreased drying time
• It made the paint more durable
• It made the paint more moisture resistant

Lead in Paint.

The durability of lead is a big reason why lead based paints still cause a problem today. Lead based paint was used for a range of coverings including walls, toys and furniture. While lead paint associated with toys and furniture is more likely to have been replaced, old flaking paint from walls can still be a source of lead exposure today. Lead poisoning from paint flakes can happen directly through contact, and indirectly through its accumulation in soils nearby³. Lead based paints for interior surfaces  were banned in 1971³and the US Department of Housing and Urban Development estimate that about 38 million homes and apartments built before 1978 contain some lead paint⁵. While this is likely to have reduced since then, there is still a significant source of lead in some home environments. In 1991, the HUD Lead Based Abatement Demonstration guidelines were published⁶, this document established guidelines for the testing, abatement, clean up and disposal of lead based paint in homes. Over the following period, the US Department of Housing and Urban Development have provided grants to local authorities to encourage homeowners to carry out improvements works to replace lead based paint in their homes, this has been extremely successful in some areas^7,8,9, however the scale of the problem, and homeowner engagement may be a challenge¹⁰. The Green and Healthy Home Initiative in the United states is also running a campaign to end lead poisoning by 2022 by advocating policy and services to assess sources of lead poisoning¹¹.

Why is lead bad?

Significant steps have been taken in the last century to reduce and remove the use of lead from a range of consumer product and industrial processes. The practical health impact of this can be seen in the graph below (Fig 1)¹², however it still remains in products such as ceramic dishes, make up, food cans and in processes carried out in under-developed countries. Even at the lower concentrations of 10µg/dl, figure 2 illustrates the detrimental impact that this level can still have.

Due to the much lower levels of lead that people are exposed to now, the main detrimental impacts do come from low-level chronic exposure. At relatively low concentrations, lead produces relatively modest or short-term effects, including elevation of blood pressure, reduction in the synthesis of hemoglobin, and decreased ability to utilize vitamin D and calcium. With increased blood concentrations of lead, however, these problems become more severe. Impairment of the central nervous system can occur, with decreased mental functioning and hearing damage as two possible results. At very high lead concentrations, a person can fall into a coma and, eventually, die¹³. At low-level chronic exposure, emotional and mental issues can develop and can be difficult to diagnose, with children being at the greatest risk in this case. In adults, chronic exposure can lead to kidney and nervous system damage, anaemia, stroke or cancer¹⁴.

Where is lead used, and what can be used instead?

While people can come into contact with lead inadvertently through flaking paint, etc, it is still used for a range of applications today. Lead is very resistant to corrosion and so is used in various products to store or contain dangerous chemicals. Tanks that hold sulphuric acid are lined with lead, and it is also used in automotive lead-acid storage batteries. In healthcare settings, X-rays can be damaging over periods of time and lead is also used to shield users, and patients from X-rays¹⁵.

With the realisation that the negative impact that lead could have, replacements were identified for the various products that contained it.

In paint, the main function of lead is as a pigment, drying agent and anti-corrosive agent⁴. A range of compounds were identified and are now used to replace the functionality of lead in paint. These are outlined below:

Table 1. Compounds used to replace lead in paint¹⁶

In gasoline, lead functioned to improve performance, help with wear and tear and reduce engine knocking. The negative impact on people producing the tetraethyl lead, as well as the potential impact through its emission into the environment, led to steps being taken to remove lead from gasoline, although this process took almost 30 years³. During this period catalytic converters were introduced to help cars adhere to clean air regulations. Lead was a catalytic converter poison and so a commercial pressure was also introduced to remove this poison from the fuel³.

There have been significant improvements in car engines in past decades and so some of the advantages of the use of tetra ethyl lead have been overcome through improved engine technology. A chemical replacement in fuel to improve performance is methyl tertiary butyl ether (MTBE). It is created from methanol and while it aids in the removal of lead, it is also thought to be a carcinogen. MTBE helps to increase the octane number of fuel, and hence performance¹⁷.

Product recalls for lead

There are limit levels for lead in a wide range of products from food to toys and textiles to solder. These are monitored in a number of different ways.

• Manufacturer compliance
• Regulatory agencies
• Third party certification testing

Where limit levels are exceeded it is the responsibility of the manufacturer to inform the relevant regulatory agency and to take proactive action in terms of product recalls. 

The limit for lead in toys is outlined below, for context, 90 parts per million (ppm) is equivalent to 0.009%.

Table 2 Limit levels of lead allowable in toys and children’s products.

There have been approximately 40 product recalls of children’s toys in the past 5 years in the EU and United States due specifically to their lead content (search based on RAPEX²¹and CPSC²²databases). In a number of products, including pencils and small toys, the paint used on the products contained excessive amounts of lead. While some products exceed the limit levels by only a small amount, some recalls are based on products having in excess of 10 times the allowed amount (Table 3).

Table 3 Example of recalled products from CPSC database with lead content measured in product and limit levels.

Lead is a well-known heavy metal that should not be in consumer products above a certain limit, however as can be seen from the data above, it can happen reasonably regularly. The US Consumer Product Safety Commission database reports on the number of items in a batch affected. From this period, recalled item batches ranged from 4,600 units to 215,000²². Should these products have not been tested and subsequently recalled, it could have resulted in a significant health impact.

In order to provide confidence to the consumer in terms of products that they purchase, there are a range of Certification Programs that take account of chemical hazards in consumer products. These include:

Consumer signposts

• US Consumer Products Safety Commission Children’s Product Certificate

The US CPSC is a federal regulatory agency with responsibility to protect the public against risks arising from everyday products. As part of this remit, the CPSC operate a certification for a range of products, including toys. The Children’s Product Certificate is based on test results provided by CPSC accredited laboratories and provides a way for companies to show that their products are suitable for normal use.

•  Oeko Tex^®

Oeko-Tex

Oeko Tex^® is a global standard for textiles and has been in existence since 1992. It certifies a range of products from curtains and jackets to bedding and baby clothing. Their certification is textile specific and its relevance for toys is with regard to any toy product that incorporates textiles. Certification is based on four product classes with increasing limit levels based on intensity of skin contact and skin sensitivity. Their focus is on ensuring a textile product poses no risk for human health. In addition to lead, the types of compounds that Oeko-Tex^® certify against include free formaldehyde, heavy metals, chlorinated phenols, colorants, tin compounds, flame retardants, volatile emissions, etc. The Oeko-Tex® standard focusses on comprehensive testing of the textile and does not address supply chain, environmental issues or organic certification.

• TÜV SÜD

TÜV SÜD are a global technical service provider of testing and product certification, as well and auditing and systems certification. Toys and children’s products are tested to comply with a range of test standards for criteria such as performance and endurance, flammability, electrical safety and also chemical testing, including lead. Products that pass testing receive the TÜV SÜD certification mark.

• asthma & allergy friendly^®

asthma & allergy friendly® Certification Program – Allergy Standards Ltd

The asthma & allergy friendly^® certification program was established in 2006. It is operated by Allergy Standards Ltd in collaboration with the Asthma and Allergy Foundation of America (AAFA), Asthma Society of Canada (ASC) and is also operated internationally through a global certification mark. ASL only certify products that have undergone physical and chemical testing at ASL accredited testing laboratories, according to specific testing standards, which include testing for lead. The asthma & allergy friendly^®  Certification Program maintains a focus on consumer products that will improve the indoor environment for those suffering from asthma and allergies.

Significant steps have been taken in the last century to remove lead from as many consumer products as possible. The global supply chain that exists today however means that manufacturers do not always have as much control and foresight over raw materials as they used to. Testing and certification is essential in order to ensure that consumer products are as safe as possible for consumer use.

Dr. Tim Yeomans

About the author 

Thanks to Dr. Tim Yeomans for this insightful article.

Dr. Tim Yeomans is the Centre Manager for Shannon Applied Biotechnology Centre, a collaboration between two third level colleges in Ireland. Tim holds a PhD in Microbiology and postgraduate qualifications in Technology Commercialisation and Innovation Management. Tim has worked in research and development for 20 years, both in industry and academia. In his role in Shannon ABC, Tim is responsible for the scientific direction of the Centre, intellectual property management and business and technology development.

Keywords 

Health, safety, consumers, manufacturers, raw materials, heavy metal, paint, indoor environment, allergy, asthma, certification, allergy insights 

References

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