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镍释放量测试

Nickel Release - New European Standards Published

The European reference test method to verify compliance with the REACH Annex XVII restrictions on nickel release from metallic articles with direct prolonged skin contact has been amended. Those products covered include ear and body piercing post assemblies, other jewellery, watches, zips and garment accessories, sunglasses etc, from which the release of nickel ions can cause sensitisation, nickel allergy and in severe cases even nickel dermatitis.

 

The former nickel release reference test method EN 1811:1998+A1:2008 has now been divided into:
EN 1811:2011 - Applies to all metallic articles with direct, prolonged skin contact, excluding spectacle frames and sunglasses
EN 16128:2011 - Covers only spectacle frames and sunglasses.

For EN 1811:2011 the significant technical changes with respect to EN 1811:1998+A1:2008 are:
Scope expanded to include all post assemblies which are inserted into pierced parts of the human body.
Test solution has been changed, replacing the ammonia solution with a sodium hydroxide solution.
The 0.1 times analytical correction factor has been replaced by measurement uncertainty, based on the results of a further interlaboratory study.
Normative Annex C has been added, specifying how various articles shall be prepared prior to nickel release testing.

EN 16128:2011 for spectacle frames and sunglasses is technically unchanged from EN 1811:1998+A1:2008, and retains the 0.1 times analytical correction factor, introduced to allow for variations between labs in an earlier interlaboratory study. This means that the analytical result from the test is multiplied by the 0.1 times analytical correction factor to give the adjusted result (that is 10 % of the analytical result) which is then compared to the limit for nickel release. Put another way, the 0.1 times correction factor means that the analytical result would have to be more than 10 times the limit to still exceed the limit after adjustment and considered to fail.

 

The shift in EN 1811 from the correction factor to a measurement uncertainty approach effectively means a significant tightening in the nickel release requirements for body post assemblies and other articles with direct, prolonged skin contact such as, jewellery, watches etc, except for spectacle frames and sunglasses (covered by EN 16128). The tables below highlight the extent of this change based on the two limits for nickel release and assuming for these purposes that each version of EN 1811 gives the same analytical result. Different treatment of the results in each version of EN 1811 can lead to opposing or inconclusive results.

 

Nickel Release from Post Assemblies for Ear and Body Piercing

Nickel Release Concentration/ µg/cm²/week

Limit/ µg/cm²/week

Compliance Assessment

Analytical Result

Adjusted Result
(EN 1811:1998+ A1:2008)

EN 1811:1998+ A1:2008

EN 1811:2011

< 0.11

< 0.011

0.2

Pass

Pass

> 0.11 and < 0.35

> 0.011 and < 0.035

Pass

Inconclusive

> 0.35 and < 2.0

> 0.035 and < 0.2

Pass

Fail

> 2.0

> 0.2

Fail

Fail

Nickel Release from Other Articles with Direct, Prolonged Skin Contact (Except for Spectacles and Sunglasses)

Nickel Release Concentration/ µg/cm²/week

Limit/ µg/cm²/week

Compliance Assessment

Analytical Result

Adjusted Result
(EN 1811:1998+ A1:2008)

EN 1811:1998+ A1:2008

EN 1811:2011

< 0.28

< 0.028

0.5

Pass

Pass

> 0.28 and < 0.88

> 0.028 and < 0.088

Pass

Inconclusive

> 0.88 and < 5.0

> 0.088 and < 0.5

Pass

Fail

> 5.0

> 0.5

Fail

Fail

Some uncertainty is inherent to any test measurement, with the true result lying anywhere within a statistical band of uncertainty calculated from many repeat measurements. For EN 1811:2011, analytical results that lie so close to the limit that their band of uncertainty overlaps the limit are therefore inconclusive. The band of uncertainty for an analytical result must lie either wholly below or above the required limit to give a conclusive pass or fail result.

 

Currently REACH Annex XVII restrictions vaguely refer to the published CEN test methods for nickel release, rather than particular standards or versions. Hence until March 2013, when EN 1811:1998+A1:2008 is withdrawn, there is an overlap period during which either version of EN 1811 may be used to demonstrate nickel release compliance for articles other than spectacle frames and sunglasses. This is an extended transition period, intended to allow more time for adjustments to be made for the tightened requirements of EN 1811:2011.

 

The Solution
ATC has developed analytical methods to verify the release of nickel from metallic articles. By leveraging our local services and global network, we enable our customers to dedicate their primary energies to their core business activities. We offer comprehensive programs and services which draw on our industry specific knowledge and technical expertise. Please contact your local ATC laboratory for further details of this and our other services.

 

 

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