Towards health-based nano reference values (HNRVs) for occupational exposure: Recommendations from an expert panel.

Unique physicochemical characteristics of engineered nanomaterials (ENMs) suggest the need for nanomaterial-specific occupational exposure limits (OELs). Setting these limits remains a challenge. Therefore, the aim of this study was to set out a framework to evaluate the feasibility of deriving advisory health-based occupational limit values for groups of ENMs, based on scientific knowledge. We have used an expert panel approach to address three questions: 1) What ENM-categories should be distinguished to derive advisory health-based occupational limit values (or health-based Nano Reference Values, HNRVs) for groups of ENMs? 2) What evidence would be needed to define values for these categories? And 3) How much effort would it take to achieve this? The panel experts distinguished six possible categories of HNRVs: A) WHO-fiber-like high aspect ratio ENMs (HARNs), B) Non-WHO-fiber-like HARNs and other non-spheroidal ENMs, C) readily soluble spheroidal ENMs, D) biopersistent spheroidal ENMs with unknown toxicity, E) biopersistent spheroidal ENMs with substance-specific toxicity and F) biopersistent spheroidal ENMs with relatively low substance-specific toxicity. For category A, the WHO-fiber-like HARNs, agreement was reached on criteria defining this category and the approach of using health-based risk estimates for asbestos to derive the HNRV. For category B, a quite heterogeneous category, more toxicity data are needed to set an HNRV. For category C, readily soluble spheroidal ENMs, using the OEL of their molecular or ionic counterpart would be a good starting point. For the biopersistent ENMs with unknown toxicity, HNRVs cannot be applied as case-by-case testing is required. For the other biopersistent ENMs in category E and F, we make several recommendations that can facilitate the derivation of these HNRVs. The proposed categories and recommendations as outlined by this expert panel can serve as a reference point for derivation of HNRVs when health-based OELs for ENMs are not yet available.

[Flying and COVID-19: options to reduce the risk of transmission]. / Vliegverkeer en covid-19.

With air travel continuing after the SARS-CoV-2 pandemic as before, is there a risk of in-flight-transmission? We found 18 papers describing a total number of 306 index patients on 150 flights, 79 infected passengers and four infected cabin crew. Infection transmission within the aircraft cabin depends on flight occupancy, proximity to the index patient, duration of flight and the prevailing virus variant. A negative PCR-test has a sensitivity of 95 %, around 5 % of travelers will get a false negative result. Airborne transmission of virus-containing saliva droplets (aerosols) is considered the most important infection mechanism; infection via contaminated surfaces is less common. Strict distancing, with an empty middle seat, is essential. The risk of in-flight transmission can be further minimized by mandatory masking, restricting passenger movements, restricting meals and beverages, frequent hand sanitizing and complying to rules while boarding or at disembarkation.

Occupational exposure limits for manufactured nanomaterials, a systematic review.

BACKGROUND: The toxicological properties of manufactured nanomaterials (MNMs) can be different from their bulk-material and uncertainty remains about the adverse health effects they may have on humans. Proposals for OELs have been put forward which can be useful for risk management and workers' protection. We performed a systematic review of proposals for OELs for MNMs to better understand the extent of such proposals, as well as their derivation methods. METHODS: We searched PubMed and Embase with an extensive search string and also assessed the references in the included studies. Two authors extracted the data independently. RESULTS: We identified 20 studies that proposed in total 56 OEL values. Of these, two proposed a generic level for all MNMs, 14 proposed a generic OEL for a category of MNMs and 40 proposed an OEL for a specific nanomaterial. For specific fibers, four studies proposed a similar value but for carbon nanotubes (CNTs) the values differed with a factor ranging from 30 to 50 and for metals with a factor from 100 to 300. The studies did not provide explanations for this variation. We found that exposure to MNMs measured at selected workplaces may exceed even the highest proposed OEL. This indicates that the application and use of OELs may be useful for exposure reduction. CONCLUSION: OELs can provide a valuable reference point for exposure reduction measures in workplaces. There is a need for more and better supported OELs based on a more systematic approach to OEL derivation.

Exposure limit values for nanomaterials--capacity and willingness of users to apply a precautionary approach.

In the European Union, the legal obligation for employers to provide a safe workplace for processing manufactured nanomaterials is a challenge when there is a lack of hazard information. The attitude of key stakeholders in industry, trade unions, branch and employers' organizations, and government policy advisors toward nano reference values (NRVs) has been investigated in a pilot study that was initiated by a coalition of Dutch employers' organizations and Dutch trade unions. NRVs are developed as provisional substitutes for health-based occupational exposure limits or derived no-effect levels and are based on a precautionary approach. NRVs have been introduced as a voluntary risk management instrument for airborne nanomaterials at the workplace. A measurement strategy to deal with simultaneously emitting process-generated nanoparticles was developed, allowing employers to use the NRVs for risk assessment. The motivational posture of most companies involved in the pilot study appears to be pro-active regarding worker protection and acquiescent to NRVs. An important driver to use NRVs seems to be a temporary certainty employers experience with regard to their legal obligation to take preventive action. Many interviewees welcome the voluntary character of NRVs, though trade unions and a few companies advocate a more binding status.

Exposure limits for nanoparticles: report of an international workshop on nano reference values.

This article summarizes the outcome of the discussions at the international workshop on nano reference values (NRVs), which was organized by the Dutch trade unions and employers' organizations and hosted by the Social Economic Council in The Hague in September 2011. It reflects the discussions of 80 international participants representing small- and medium-size enterprises (SMEs), large companies, trade unions, governmental authorities, research institutions, and non-governmental organizations (NGOs) from many European countries, USA, India, and Brazil. Issues that were discussed concerned the usefulness and acceptability of precaution-based NRVs as a substitute for health-based occupational exposure limits (OELs) and derived no-effect levels (DNELs) for manufactured nanoparticles (NPs). Topics concerned the metrics for measuring NPs, the combined exposure to manufactured nanomaterials (MNMs) and process-generated NPs, the use of the precautionary principle, the lack of information about the presence of nanomaterials, and the appropriateness of soft regulation for exposure control. The workshop concluded that the NRV, as an 8-h time-weighted average, is a comprehensible and useful instrument for risk management of professional use of MNMs with a dispersible character. The question remains whether NRVs, as advised for risk management by the Dutch employers' organization and trade unions, should be under soft regulation or that a more binding regulation is preferable.

Building blocks for a precautionary approach to the use of nanomaterials: positions taken by trade unions and environmental NGOs in the European nanotechnologies debate.

As partners in the European capacity-building project NanoCap, trade unions and environmental nongovernmental organizations (NGOs) have established positions on the development of nanotechnologies. Key in their positioning is their view that the use of nanomaterials with currently unknown occupational and environmental hazards must have consequences for the risk management and use of nanoproducts. They have made proposals for responsible manufacturing and for applying the precautionary principle to the use of nanoproducts and they urgently call for the acceptance and the operationalization of a precautionary approach by the industry and governments. The trade unions and NGOs are calling for transparency and openness regarding processes and products that contain nanomaterials and have proposed specific tools for nanomaterial use that put the precautionary principle into practice, including the principles no data → no exposure and no data → no emission. The proposed tools also include compulsory reporting of the type and content of nanoparticles applied in products, a register of workers possibly exposed to nanoparticles, and the use of nano reference values as guides to assess workplace exposure to nanoparticles.

Dealing with uncertainties in the nanotech workplace practice: making the precautionary approach operational.

If the risk management for the professional use of dispersive nanomaterials is hampered by a lack of reliable information, the reliable manager and the policy makers have to chose to make the precautionary principle operational for nanotech workplace. This study presents some tools that can be useful for the health & safety manager and for nanotech workers to deal with uncertainties in the nano-workplace.

NanoLINEN: nanotoxicology link between India and European Nations.

Nanotoxicology link between India and European Nations (NanoLINEN) is a consortium of 7 European laboratories and Indian Institute of Toxicology Research (CSIR Laboratory) from India to strengthen the research ties in the area of Nanomaterial Toxicology. The goal of this project is to develop robust risk assessment methodologies that will be useful for the community manufacturing and using nano-products.