Interview: Dust Potential of Feed Additives, a Matter of Growing Concern – Orffa

Feedinfo, September 2018

5 September 2018 –EFSA and the European Commission are increasingly taking the dust potential of feed additives into account as part of their risk assessment for new authorizations. Recent additive authorizations are seen to include descriptions and provisions related to the particle size and dustiness of the additive concerned, whereas additive regulations of previous decades did not consistently include such provisions. 

Directive 98/24/EC lays down minimum requirements for the protection of workers from risks to their safety and health arising from the effects of chemical agents that are present at the workplace. This directive also establishes a list of binding occupational exposure limit values which employers should take into account. Orffa respects workers safety and observes how this trend is followed on a global level.

Brecht Bruneel, International Technical Manager at Orffa, argues that there should be more focus at feed manufacturing plant level on using additives with reduced dusting potential considering the worker safety legislation in place. In an interview with Feedinfo News Service, Mr. Bruneel pointed out that new trace elements which are dust free and ensure worker safety are readily available on the market.

[Feedinfo News Service] Mr. Bruneel, in your view, why are EFSA and the EC so concerned about an additive’s particle size and dustiness?

[Brecht Bruneel] Some feed additives are recognized as occupational hazards for which inhalation represents the main route of exposure. When there is a possibility that the commonly accepted threshold limit value (TLV) for a specific compound in air will be exceeded, due to high dusting potential of the additive, there is a toxicity risk. In this case the dusting potential should be lowered to ensure workers safety. This is the translation of the Worker Safety legislation (89/391/EEC) into Feed Legislation at premix and feed manufacturing level. Former decade additive regulations did not include dust provisions, but recent authorizations include descriptions and provisions related to the particle size and dustiness of the additive concerned. Guidelines for such evaluation were published in the EFSA Journal in 2012.

Brecht Bruneel – International Technical Manager Orffa

[Feedinfo News Service] In which type of feed additive is there a priority to assess the dusting potential and put in place provisions in the authorization?

[Brecht Bruneel] There is a high concern to assess the dusting potentials of trace minerals. These compounds are being sold as highly concentrated feed additives and can thus be toxic for humans even when the dusting potential is low. To limit dust some (trace) minerals have detailed composition requirements taken up in their specific authorization. Di-copper chloride trihydroxide (3b409), for example, can be placed on the EU market only when a maximum of 1% of the additive has a particle size lower than 50 µm. This is also true for zinc chloride hydroxide monohydrate (3b609). Other trace elements (e.g. cobalt and iodine) have similar detailed composition requirements to limit dust. As physical dedusting is very difficult for trace elements, technological additives or feed materials included in the preparation of an additive are also possible ways to reduce the dusting potential of certain feed additives. This specific provision is taken up in the authorization of the organic selenium source, L-selenomethionine (3b815). Here, the registration holder is obliged to make a preparation which ensures that the dusting potential of this compound is lower than 0.2 mg Se/m3 air (TLV). This limit is immensely important taking into account the extremely toxic nature of the element selenium upon inhalation. Excential Selenium 4000, produced by Orffa, complies with this limit as the first and only organic selenium source in the market and therefore guarantees workers safety.

[Feedinfo News Service] What can be done at the feed manufacturing plant level to minimize the dust issue?

[Brecht Bruneel] For a feed manufacturing plant it is of the utmost importance to stay clean and dust free. However the realization of a dust free factory is far from obvious. Several manufacturing processes produce dust and the dust production can only be eliminated when every dust critical point in the factory has a dust extraction installation. These installations are costly and have to be regularly inspected and evaluated on their efficiency. In the feed and flower mill industry, dust has never been far away. But it becomes more harmful when the dust contains also additives which are harmful for the environment and have to be disposed of in an appropriate manner. Even when dust extraction is applied throughout the factory a dusty product is difficult to dose and implies loss of product which is not desirable. That is why dust-free products are of interest to feed manufacturers. They are increasingly realizing that dust-free products are readily available in the market helping them to ensure workers safety and minimizing other disadvantages linked to dusty products.

[Feedinfo News Service] Selenized yeast compounds registered before 2014 have had their dusting potential assessed by EFSA, but specific EU regulations were lacking dust restrictions. L-selenomethionine is the first organic selenium compound where dust is regulated by EU law. For you, does this provide a competitive edge to L-selenomethionine over these selenized yeasts available in the market?

[Brecht Bruneel] It is indeed so that selenized yeasts registered before 2014 had their dusting potential assessed but the EC did not take up dust restrictions in the specific authorizations. When looking at the specific EFSA opinions, the dusting potentials mentioned were above the TLV (0.2 mg Se/m3 air). Excential Selenium4000, which is a dust free preparation of L-Selenomethionine (3b815), is the first organic selenium source available in accordance with the 0,2 mg Se/m³ limit. This provides a competitive edge because it will not expose workers to toxic inhalable fractions of selenium. I would like to stress that making a dust free product does not happen overnight. It requires in-depth technological knowledge on product properties and the production process. Next to this Excential Selenium 4000 provides all its selenium (100%) in the active form. The minimal value for L-selenomethionine in selenized yeasts in legislation is, depending on the source, 63% for the majority of the selenized yeasts (only one selenized yeast has a minimal value of 70%). Meaning that 63% of the total Se content in selenized yeast products must be in the form of L-selenomethionine. These minimal levels were proposed by the selenized yeast suppliers as the quality standard of these feed additives and finally these values were integrated in the EU regulations. Although these minimal levels have to be met in order to sell these feed additives in the EU, it is stated in literature that there is a huge variation in L-selenomethionine levels. Problem is that hardly anybody analyses and guarantees are only given for the selenium content. The levels vary in literature between 24.8 % and 68.9%. Orffa initiated in 2015 its first commercial selenized yeast sample review where these levels were confirmed. 28 samples from 7 producers – majority from EU origin, some samples from outside EU – were taken up in the review. The levels of L-selenomethionine varied between 20% and 74%. The latest commercial sample review of this year revealed the same trend. 10 selenized yeasts from 4 producers showed a variation in L-selenomethionine, the quality indicator, between 29% and 64%. It is striking to see that the same producers are still placing selenized yeasts containing too low levels of L-selenomethionine on the EU market and do not comply with their EU authorization. It is not only a matter of regulatory compliance, but also results in a product with lower biological efficacy and quality as such. Excential Selenium 4000 is the only organic selenium source that can deliver the maximum amount of L-selenomethionine considering the organic selenium supply limitations in place.

[Feedinfo News Service] … and compared to the hydroxy-analogue of selenomethionine?

[Brecht Bruneel] The hydroxy-analogue of selenomethionine, OH-SeMet (3b814), authorized in 2013, was also analyzed on its dusting potential during EFSA evaluation. The dusting potential, measured by the Stauber-Heubach type II method, ranged from 4.4 to 5.9 g/m3 for six batches. Selenium concentration in the dust amounted to 9-11 mg/g. The level of mg Se/m3 air would then amount to 39.6-64.9. This numbers exceeds the TLV (0.2 mg Se/m3 air) more than 100 times. EFSA concluded that inhalation exposure of this additive poses a hazard to users, but the specific EU regulation lacked at that time a dust restriction. Orffa analyzed commercial samples of OH-SeMet and found similar values, confirming the very high dusting potential of OH-SeMet. There is another more metabolic difference between L-selenomethionine and OH-SeMet. OH-SeMet has to be converted in the animal to L-selenomethionine before it can be incorporated in the proteins. The same is known very well for the hydroxy analogue of methionine. In literature, the conversion of the hydroxy analogue of methionine is marked at 80% for chicken and pig (EFSA Journal 2012; 10(3):2623). This observed lower efficacy was confirmed by in vivo tests evaluating the Se deposition of different selenium sources in broiler breast samples. Rovers et al. 2016 and Van Beirendonck et al. 2018 both confirmed an 80% efficacy of the OH-SeMet source compared to L-selenomethionine in augmenting selenium concentration.

[Feedinfo News Service] EU feed additive manufacturers can be anxious when EFSA scientific opinions of their products are published. EFSA may have different interpretations of the safety and efficacy of the product with regard to animal performance. The worker safety aspect (inhaling, handling) might appear as secondary. In Orffa’s view, shouldn’t the worker safety aspect be prioritized over the animal performance potential?

[Brecht Bruneel] In current EFSA evaluations several aspects (identity, safety, microbiology, efficacy and quality) are taken into account when evaluating feed additives and deciding whether to authorize them for use in the EU. In order to review compliance, and a post marketing approach is added as well. Orffa is in favor of the current approach of taking all aspects into account at the same time, but there should be a focus on dusting potentials in new authorizations and re-authorizations. When EFSA states that during the (re-)evaluation of a feed additive the dustiness of the additive exceeds the TLV by several orders of magnitude and there is a risk for users upon inhalation a dust provision should be taken up in the authorization. Here the Worker Safety Legislation should be applied. Dust elimination via a control on particle size or the addition of technological additives is possible (e.g. Excential Selenium 4000). These technologies are already being applied and dust-free products are being produced, so there should be an incentive for feed additive manufacturers to control the dust of their products as well.

[Feedinfo News Service] Do you view current dusting potential provision by EFSA as a burden or relief? What kind of advice can you offer?

[Brecht Bruneel] Fulfilling to EFSA strict guidelines requires clear steps in product development and production technology. Such investments may delay market entrance of new innovative concepts, yet clear thought is giving to market a sustainable product that takes safety for people and environment into account. It is however not more than logic that the industry takes worker safety seriously. Applying such rules for all products that have been registered over the last decades is not done overnight and needs to be done in a pragmatic way. We welcome these strict guidelines, yet hope that in due time EFSA also manages to control strict rules set for commercial products available in the market and also ensure that same guidelines will be applied gradually for all products (including those Se additives registered prior to 2014) in order to create a level-playing field for all products and producers.

We do not consider current regulations as a burden though. Being compliant to strict guidelines set by EFSA and the EC also creates a Unique Selling Point in quality point of view for customers both in and outside the EU market. Orffa creates, selects and delivers very high quality products that enable feed manufacturers to respect workers safety and reap the benefits. Excential Selenium 4000 is the only organic selenium source in the market that can bring them a dust-free and fully bioavailable source.