Tjoena Siere was a Scientist at Keller and Heckman who retired in March 2025. She provided technical guidance to the firm’s attorneys in the regulatory compliance of substances used in food-contact materials, including those intended for contact with drinking water. Using her expertise in analytic chemistry, Tjoena frequently prepared and submitted petitions to the European Food Safety Authority (EFSA) and other EU national authorities, such as the Dutch G4 Commission and the German BfR.

Tjoena prepared test protocols for overall and specific migration testing and the migration of oligomers and other non-intentionally added substances (NIAS) in support of petition dossiers and opinion letters. In addition, she evaluated the migration test results reported by clients and then advised on the reliability of the results presented and their relevance for the intended application. If required, she also gave guidance to the test lab. Tjoena also evaluated client information and advised on data needed for petition dossiers. She was regularly invited to speak at industry conferences and events.

Prior to joining Keller and Heckman, Tjoena worked at a global research institute, focusing on food packaging. As a food-contact materials and legislation project manager, she prepared custom-made project proposals to enable her clients to meet their business goals. While in this position, she was also involved in the evaluation of the composition of food-contact materials based on national, European, and U.S. legislation. Tjoena also prepared and submitted dossiers to the relevant authorities for the authorization of new substances and supervised the migration studies required for both compliance testing and petitioning, including specific migration and screening studies on migrating oligomers and reaction products.

Tjoena’s vast knowledge of the authorization of new substances, particularly food-contact materials, benefited our partners and their clients when hands-on experience with the filings of various dossiers was needed.  

If you need to contact a Keller and Heckman scientist, please email info@khlaw.com.