The Facts About Lead Levels in North American Zinc Die Castings

In a recent article in Window & Door Magazine, Lawrence Industries alleged concern about levels of lead in zinc die castings—a material commonly used in the manufacture of window hardware. Included in this claim was the possibility of potentially unsafe concentrations of lead at surface levels of these products. In order to clear up any misconceptions that may have stemmed from these claims, the North American Die Casting Association (NADCA) is clarifying the facts about the quality and safety of North American zinc die cast products.

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While lead is an inherent component in many materials, including zinc, the amount of lead that is contained in these products is quite small and varies depending upon the quality and/or type of material used. Various U.S. and European regulations limit the amount of lead in various products. This is done not only to govern the limits of lead at levels which are deemed safe for consumers, but also to ensure that the purity of the zinc is such that it eliminates the possibility of material deficiencies that may jeopardize the integrity of the manufactured product.  For instance:

  • The U.S. Consumer Product Safety Improvement Act (CPSIA), which covers products designed for use by children, currently requires a lead content of less than 300 ppm (0.03% concentration).
  • The EU’s Restriction of Hazardous Substances (RoHS) requires a lead content of less than 1,000 ppm (0.1% concentration).

Currently, all certified North American-produced zinc alloys have lead content levels that fall well below 50 ppm (0.005%).  The ASTM B86 specification for zinc #3 (also known as Zamak 3), which manufacturers of zinc die cast window hardware must adhere to in North America, is shown in Table 1.


Alloy
Al Mg Cu Fe Pb Cd Sn Ni
Zamak 3 3.7-
4.3
0.02-
0.06
0.1 max 0.05
(500 ppm)
0.005
(500 ppm)
0.004
(40 ppm)
0.002
(20 ppm)
––
 

Table 1. ASTM B86 Specification for Zamak 3 Die Casting

The maximum allowable lead concentration is found under the column heading “Pb,” the symbol for lead. As shown in the table, the lead concentration in zinc die casting alloys commonly used in window hardware falls well below the levels dictated by any environmental act or regulation. Moreover, the Consumer Product Safety Commission has publicly confirmed that the CPSIA does not cover window hardware, and U.S. EPA has also confirmed to the market that its new RRP regulations on lead-paint removal have nothing to do with material selection for window hardware.

Furthermore, there are several “over-the-counter” methods to test lead, including the wipe test and the test kit. The wipe test, within the limits of its capabilities, cannot be used accurately for lead in zinc because of the ranges it measures. The kit method is inexpensive and easily accessible, but cannot be relied upon for accurate results. The best and only true way to test for lead in zinc die casting is through spectrographic analysis. This analysis should be and is provided by any reputable zinc die casting company.

As stated earlier, the concentration levels of lead are regulated not just because of the consumer safety impact of the material, but also because this helps ensure that the die cast product maintains its structural integrity. Intergranular corrosion, a condition which could occur if higher levels of lead were able to form at surface areas, is eliminated when Zamak 3 alloys are used since the concentrations of lead cannot surpass the 50 ppm threshold in these areas. Consequently, the strength of the product is not compromised, and the concern of unsafe levels of lead at surface areas is eliminated. The North American Die Casting Association would like to thank consumers for the support and confidence they have shown by making die cast products the material of choice for so many years. NADCA pledges that it will continue to work diligently and responsibly to provide dependable, reliable and safe products for use in the window and door market.

Summary

1. The amount of lead contained in zinc die cast products is quite small and varies depending upon the quality and/or type of material used. The U.S. Consumer Product Safety Improvement Act (CPSIA), which covers products designed for use by children, currently requires a lead content of less than 300 ppm (0.03% concentration) and the EU’s Restriction of Hazardous Substances (RoHS) requires a lead content of less than 1,000 ppm (0.1% concentration). Currently, all certified North American-produced zinc alloys have lead content levels that fall well below 50 ppm (0.005%).

2. The lead concentration in zinc die casting alloys commonly used in window hardware falls well below the levels dictated by any environmental act or regulation. Moreover, the Consumer Product Safety Commission has publicly confirmed that the CPSIA does not cover window hardware, and U.S. EPA has also confirmed to the market that its new RRP regulations on lead-paint removal have nothing to do with material selection for window hardware.

3. There are several “over-the-counter” methods to test lead, including the wipe test and the test kit. The wipe test, within the limits of its capabilities, cannot be used accurately for lead in zinc because of the ranges it measures. The kit method is inexpensive and easily accessible, but cannot be relied upon for accurate results. The best and only true way to test for lead in zinc die casting is through spectrographic analysis which should be and is provided by any reputable zinc die casting company.

Test Results

One of the points by Lawrence Industries in a recent article in Window and Door magazine was that the lead in zinc window and door hardware is easily demonstrated when using a lead check test kit. A series of simple tests were performed using the Lead Check swabs alluded to in the article.


Analytical Standard Disks of zinc alloy #3 were used as the test pieces. The four test samples contained 0.003%, 0.008%, 0.009%, and 0.1% lead. Each disk was prepared by machining with a lathe to ensure a clean fresh surface. In all tests, the presence of lead was indicated by the formation of a red color.

The color formed on the swab and the surface of the test piece. The color intensity on the swab increased with lead concentration from just visible to visible with increasing lead content. The distinction was not so clear on the test piece surface.

The test does what it claims―it detects lead. In fact, it claims to detect lead as low as 1-2 micrograms. The problem is that it detects lead at low levels, so even objects that are within allowable limits (the lead content in zinc alloys is considerably lower than even RoHs limits) will indicate the presence of lead.  This test can, therefore, be misleading and cause concern when there is none.

Helpful Links

1. Consumer Product Safety Improvement Act (CPSIA)

2. EPA’s Renovation, Repair & Painting (RRP) Rule

3. Home Safe Training