UK Amends Approval Restrictions for Pesticide Ingredient Fenpyrazamine, Addressing Impurity Limits

Key Regulatory Changes for Fenpyrazamine

In its recent review, HSE concluded that fenpyrazamine continues to meet the approval criteria established under Great Britain’s adapted version of Regulation No 1107/2009, governing plant protection products (PPPs). However, the agency highlighted the need for enhanced purity standards, requiring that fenpyrazamine’s active substance purity be at least 960 g/kg. Additionally, the new regulation sets a strict limit for hydrazine, a concerning impurity, to a maximum of 1 mg/kg (0.0001% w/w)​​.

Scientific Basis for Regulatory Amendment

The initial approval of fenpyrazamine, a pesticide active ingredient, did not account for hydrazine content, as the pilot plant production data did not indicate any impurities. However, recent commercial-scale evaluations conducted by HSE, based on data from the European Rapporteur Member State (RMS) Austria, have identified hydrazine as a potential impurity arising during commercial manufacturing. Hydrazine is known for its toxicological risks, although studies indicate it does not present a toxicological concern at the new maximum level of 0.0001%​.

The decision aligns with amendments in the EU, where updated standards were implemented in March 2021, mandating a similar 1 mg/kg impurity limit following Austria’s 2013/2014 review. This revision by HSE harmonises Great Britain’s regulations with these EU standards​.

No Disruption to Current Product Usage

This amendment does not require a grace period, as products containing fenpyrazamine already comply with the revised impurity standards. Manufacturers and users can continue to operate without interruption, as long as products adhere to the updated purity specifications. The revised approval conditions are now reflected in the UK’s GB Approvals Register for pesticides, accessible on the HSE website​​.

This regulatory update reinforces HSE's commitment to rigorous safety standards for active ingredients in plant protection products, underscoring the importance of ongoing scientific review to mitigate health and environmental risks.