Some thermo plastics are anti-static and conductive, so it isn't impossible that the plastic on the handles is conductive/earthed.
"ATEX – Eliminating explosion risks in hazardous athmospheres
Ensuring people and environment safety is the most important issue when vapors, gases and dusts are processed, transported and used.
ATEX directive (1999/92/EC) regulates the use of plastic materials both in hazardous areas (ATEX zones) and in the equipment used in those areas.
Electrically conductive plastic compounds are ATEX applicable plastic materials. They fulfill the surface resistance requirement set for plastic materials in used ATEX applications." from https://www.premixgroup.com/product-cats/conductive-compounds/what_are_conductive_plastics/