The Restriction of Hazardous Substances (RoHS) Directive continues to evolve with technological advances and environmental priorities. Among its many exemptions, Exemption 46 under Annex III plays a critical role in allowing the use of certain restricted substances under specific conditions. This blog post delves into RoHS Exemption 46, explains its purpose, outlines its current status, and provides concrete examples to clarify its practical implications for manufacturers and importers.
Exemption 46 under Annex III of RoHS refers to:
“Cadmium telluride and cadmium zinc telluride in detectors for ionising radiation.”
This exemption permits the use of cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) in ionising radiation detectors, despite cadmium being a restricted substance under RoHS. Normally, cadmium use is limited to 0.01% by weight in homogeneous materials. However, for this specific application, the exemption allows concentrations above this threshold due to the lack of suitable alternatives.
Ionising radiation detectors are vital for several sectors, including:
Medical imaging (e.g., CT scanners, PET scanners)
Security screening (e.g., airport baggage scanners)
Industrial inspection (e.g., non-destructive testing of welds)
Scientific research (e.g., high-energy physics detectors)
These detectors rely on CdTe and CdZnTe materials because of their exceptional sensitivity, compact size, and operational efficiency at room temperature. As a result, removing these substances without viable replacements would hinder essential technological applications.
Let’s explore how this exemption works in real-world scenarios:
A positron emission tomography (PET) scanner in a hospital may contain a CdZnTe-based radiation detector. These detectors provide high-resolution images that help doctors diagnose cancer or neurological conditions with greater precision. Without Exemption 46, these machines would not meet RoHS limits for cadmium, leading to compliance issues or even discontinuation of supply.
Security systems at airports use X-ray scanners equipped with cadmium telluride detectors. These systems quickly analyze the contents of luggage to detect weapons or hazardous materials. Removing CdTe from these systems would compromise performance and slow down screening processes, thereby reducing safety.
Manufacturers often use non-destructive testing (NDT) to examine structural integrity, such as weld joints in aircraft components. CdTe detectors can identify microscopic flaws that other sensors might miss. Thanks to this exemption, industries can maintain high safety standards without breaching RoHS regulations.
Example: A metal recycling facility uses handheld XRF analyzers containing cadmium-based detectors to quickly identify and sort ferrous and non-ferrous scrap metals. This helps avoid contamination and ensures accurate alloy classification before melting.
Example: Engineers inspect old buildings for hazardous materials like lead paint or asbestos using portable XRF devices. These cadmium-based detectors enable non-destructive, on-site analysis to ensure worker safety and environmental compliance.
Example: In upstream operations, XRF detectors are used to analyze geological core samples for trace elements such as strontium, barium, and uranium. Cadmium detectors offer precise quantification, critical for assessing drilling potential.
Example: Authorities use XRF guns to screen imported jewelry for cadmium content, especially in children’s items. This ensures compliance with EU safety directives and prevents harmful exposure.
Originally, Exemption 46 was introduced with a validity period to encourage the development of safer alternatives. However, the European Commission has periodically reviewed and renewed this exemption due to the technical impracticality of replacing CdTe and CdZnTe in certain detectors.
As of now, Exemption 46 is still active, and its renewal applications are evaluated by the Öko-Institut, which assists the EU in performing technical assessments. Stakeholders can submit evidence to support or challenge the renewal of exemptions based on technological feasibility and environmental impact.
Not likely—at least not yet. Although there is ongoing research into alternative materials like mercury iodide and perovskite semiconductors, they still fall short in key performance areas. For instance, most alternatives:
Struggle to match the energy resolution of CdTe/CdZnTe
Require active cooling systems
Cost more and have limited availability
Consequently, unless a groundbreaking innovation emerges, industry players continue to rely on this exemption to manufacture high-performance radiation detectors.
Manufacturers and importers who rely on Exemption 46 must:
Document their use of CdTe or CdZnTe in radiation detectors.
Demonstrate necessity, showing no viable alternatives exist.
Monitor the exemption’s status, as expiration or non-renewal could trigger compliance risks.
Stay transparent with supply chain partners regarding exemption use.
For example, a Canadian manufacturer exporting X-ray detectors to the EU must maintain technical documentation showing that the product qualifies under Exemption 46. Otherwise, customs officials could seize the shipment for exceeding cadmium limits.
Should the EU decide to phase out Exemption 46, affected industries will face multiple challenges:
Redesign costs for replacing key components
Potential delays in production
Market disruptions, particularly in healthcare and security
Need for alternative compliance strategies, such as ceasing EU exports or applying for new exemptions
Therefore, affected businesses must prepare in advance by investing in R&D, engaging in advocacy, and diversifying suppliers.
To future-proof your operations, consider these proactive steps:
Track the latest RoHS updates via the European Chemicals Agency (ECHA) and EU Commission announcements.
Collaborate with researchers to explore cadmium-free detector materials.
Train internal teams to adapt designs and documentation quickly when exemptions change.
Partner with environmental compliance consultants to assess risks and prepare renewal applications if necessary.
RoHS Exemption 46 enables critical technologies to operate without sacrificing compliance. It supports vital sectors such as healthcare, security, and industry, which depend on accurate and reliable ionising radiation detection. Although the EU aims to reduce hazardous substances, it recognizes the need for balance when no safe substitutes exist.
While this exemption is not permanent, it remains crucial in enabling innovation where performance and safety matter most. Thus, companies using Exemption 46 must stay informed, plan strategically, and remain engaged with the regulatory process to maintain compliance while contributing to sustainability goals.
Contact Enviropass to learn more about ROHS and how to assess your products against it.
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