Improve bee health by reducing contamination of the wax used in beekeeping

To keep their bees healthy, beekeepers regularly renew the wax in the frames that make up the hive. They purchase sheets of embossed wax, which, when inserted into the frames, serve as a foundation on which the bees can build their cells. For economic reasons, these foundation sheets are generally produced from recycled wax (the wax is melted and then reused). This recycling can lead to the gradual accumulation of chemical contaminants that are potentially harmful to bees.

ANSES conducted an expert appraisal to review the chemical contaminants found in beekeeping wax in mainland France, as well as any adulterants, i.e. substances found despite not being an ingredient of natural beeswax. The expert appraisal was based on the data available in the scientific literature and on field surveys carried out in mainland France with wax-workers, professional beekeepers and suppliers of wax to amateur beekeepers.

Certain chemical contaminants detected are toxic to bees

Examination of the data from the French field surveys found numerous chemical contaminants in the wax sold in France. These include residues of biocides, plant protection products, veterinary medicines and trace metals, of environmental or beekeeping origin (i.e. for controlling the parasitic mite Varroa destructor). When veterinary medicines against Varroa are applied in accordance with the instructions, particularly concerning the dose and frequency, they account for only a small proportion of the overall toxicological risk associated with wax contaminants.
Among the substances of greatest concern accumulated in wax, pyrethroids were found in over 40% of samples from wax foundations on the market. A chemical risk quotient was calculated for all the analysed samples, which showed that these are the substances that pose the greatest risk to bees. This quotient takes account of the levels of all the substances found in each sample and their intrinsic toxicity to bees.

Piperonyl butoxide, detected in over 50% of these samples, increases the insecticidal action of pyrethroids. This combination therefore poses an even greater threat to bee health. In addition, the study found substances that have been banned in France for several years, in particular acaricides, since the wax sold may have come from anywhere in the world. 

The origin of the wax determines its level of contamination and the risk to bee health

The expert appraisal also noted that the level of chemical contamination of the wax varied according to its origin. The foundation sheets posing the lowest risk were those made from wax directly produced by bees and then reused by beekeepers (self-renewal). Re-melting and re-using your own wax is only possible if you have enough hives or are a member of a beekeepers' association. The majority of beekeepers who do this are therefore professionals.

Commercially available wax contains a variable number of contaminants. The composition of wax foundation sheets used for beekeeping is not currently regulated. Wax sold by wax-workers poses a lower risk than that sold by more general purpose retailers. There are also statistically fewer toxicological risks to bees from wax originating in France than wax from other EU and non-EU countries.

Wax that is newly secreted by bees and has therefore never been recycled, such as the wax used to cap honey cells, poses the least risk to the health of bees and the colony.

Traces of wax adulteration

The analyses also showed that 70% of wax samples contained small quantities of paraffin (less than 1% of the product). Paraffin is sometimes fraudulently mixed with beeswax to reduce the cost. However, the small quantities measured in this review suggest that these were residues from successive recycling operations rather than intentional additions. Paraffin's toxicity to bees is not known, but high levels of it in wax can lead to the foundation sheet melting just after it has been introduced into the hive, preventing the bees from using it. Stearic acid, another adulterant, was detected in fewer than 4% of samples. However, it is highly toxic to bee broods.

Recommendations to reduce wax contamination

The substances accumulated in wax are one of several factors contributing to the increase in bee mortality observed in recent years. ANSES is making recommendations to the various beekeeping stakeholders to improve the quality of the wax used and protect bee health:

For beekeepers:

• if possible, recycle your own capping wax, joining forces with other beekeepers if necessary,
• source the highest quality wax possible (French capping wax),
• choose practices that recover wax recently secreted by bees,
• use medicines that are least likely to accumulate in the wax (hydrophilic),
• follow the good beekeeping practices prescribed by the Technical and scientific institute
• for beekeeping and pollination (ITSAP) when renewing hive frames and for medicinal treatments.

For wax-workers:

• state the geographical origin of the wax and its relative composition (when several types of wax are combined),
• draw up a good practice guide for verifying the composition of wax,
• ensure the traceability of the wax, from its production through to the pressing of the sheets.

For the authorities:

• develop a regulatory definition of beeswax for use in beekeeping, to provide a framework for its use,
• establish a toxicological threshold above which a wax can no longer be used for beekeeping. In the current state of knowledge, ANSES recommends taking a risk quotient of less than 5000 as the threshold. This quotient is calculated using the Bee Tox Wax tool developed by the University of Liège and takes account of the levels of all the substances found in the wax sample and their intrinsic toxicity for bees,
• make it mandatory for wax-workers to be accredited,
• insist on the traceability of the wax sold.

ANSES also recommends conducting research into the exact composition of natural beeswax, in order to establish official benchmarks for identifying adulterated wax.