**Abstract**

The regulation of chemical substances involves a negotiation between social actors to translate controversial scientific evidence about risks into legal norms. This chapter addresses the discussion elicited by a public consultation on a voluntary regulation guide on silver nanoparticles (AgNP) in workplaces. It examines the comments made from 2016 to 2018 by diverse social actors – business representatives, non-governmental organizations (NGO), and independent researchers – to two successive draft versions of a Recommended Exposure Limit (REL) in working environments with AgNP. The REL is a voluntary guideline on permissible exposure limits elaborated by the NIOSH in the U.S. The methodology used was a qualitative content analysis, structured upon a historical and sociotechnical contextualization of nanotechnologies carried out through literature review. The findings show how different social actors position themselves in the controversy, revealing a pattern of behavior consistent with their position in the research, production, and commercialization of this new nanomaterial. While a group of actors, aligned with the interests of AgNP producers, proposed the restriction of mandatory and AgNPspecific regulation, another group of more heterogeneous actors, identified with the interests of workers and consumers, demanded more scientific and technical information and stricter health protection measures.

**Keywords:** nanosilver, risks, recommended exposure limits, regulation, occupational health

## **1. Introduction**

The regulation of chemical substances involves a difficult negotiation between social actors to translate often controversial scientific evidence about risks and safety into legal norms. When the regulation faces chemical substances with uncertain risk, as in many of the nanomaterials, the difficulties increase.

This article addresses the public discussion of a proposal for a voluntary guide to regulate the exposure limits to silver nanoparticles (AgNP) in workplaces in the United States. The draft guide, known as *Recommended Exposure Limits* (REL), was prepared by the *National Institute for Occupational Safety and Health* (NIOSH) on-demand from the *Centers for Disease Control and Prevention* (CDC), and went through two stages of discussion and rework during 2016–2018. We examine the public online discussion of both drafts by different social actors, basically academics, business organizations, and non-governmental organizations (NGOs).

Analyzing this discussion required placing nanotechnologies in their historical and socio-technical context. Nanotechnology is the intentional manipulation of matter to form new structures with a dimension smaller than 100 nanometers. Nanoparticles have particular physical–chemical properties (electrical, optical, magnetic, thermal, mechanical) and are different from the same material on a larger scale [1]. The interaction of nanoparticles with biological systems is highly unpredictable and their use may involve unknown risks [2].

From mid-2000s there was an explosion of nanotechnology products in the market. Although there are no detailed records, StatNano [3] registered 8 452 products until November 2018, present in almost all economic sectors.

The development of this emerging technology coincides with the wake-up call by the World Health Organization and the United Nations Environment Program on the global pandemic caused by toxic chemicals [4]. These organizations indicate that about five million people die annually from the exposure and handling of chemical substances and contact with consumer items that contain them [5, 6].

Silver is a metal known both for its toxicity and for its healing effects since ancient times [7]. Currently, its use in the form of nanoparticles is blossoming. The inventory of nanotechnology products of the *Woodrow Wilson International Center for Scholars* identified 442 using AgNP, and reports that silver is the most commonly used nanomaterial in the whole set of products [8, 9]. The antibacterial properties of AgNP justify its use in textiles, food packaging, paints, toys, environmental technologies, cosmetics, implants, and other medical devices; they are also used in the electronics industry (semiconductor printing, radio frequency identifiers, flexible circuits, solar panels) [10–12]. The United States produced 20 tons of AgNP in 2010; in 2014 between 450 and 542 tons were produced at a word level [13].

Toxic effects of AgNP on the human organism have been detected when certain exposure levels are exceeded [14]. In the workplace, the AgNP enter the body mainly through inhalation. The final destination within the organism is uncertain. Whereas there was a consensus to consider that were the lungs, more recent research has showed that they can move from the lungs to the liver, and eventually to the spleen and kidneys, accumulating [12], thus exposing workers to a variety of potential health threats. These characteristics of AgNP have raised the concern of CDC of the United States, which has recommended NIOSH to develop a voluntary guide (REL) of permissible exposure for AgNP [15].

The toxicity of silver in larger sizes, when certain exposure limits are exceeded, is already widely known, causing, for example, argyria, and there are safety regulations in this regard [16]. With the increasing use of AgNP, a debate arises about whether, in smaller sizes, such as nanoparticles, the toxicity of silver remains the same, as some of the actors who participated in the public consultation analyzed here argue, or if toxicity manifests itself differently, as other actors claim.

Regarding occupational safety, there are mandatory regulations and voluntary guides. In the United States, a chain of regulations can be identified. The first is the *Occupational Exposure Limits* (OEL), which are scientific studies about the maximum acceptable limit of particles in workplaces of hazardous substances of certain material or class of materials. The OELs are established considering functional categories (exposure period time according to the degree of concentration, maximum exposure, and an emergency category when danger is imminent).

Based on OEL, mandatory workplace standards called *Permissible Exposure Limit* (PEL) are developed. These are prepared by the *Occupational Safety and Health Administration* (OSHA). Voluntary standards, such as the Recommended Exposure Limit (REL) examined in this chapter can also be developed, often based on OELs. These are elaborated by NIOSH.

**241**

*AgNano, the Construction of Occupational Health Standards: A Status Update*

On December 18, 2015, the NIOSH put out a first REL draft, entitled *Current Intelligence Bulletin: Health Effects of Occupational Exposure to Silver Nanomaterials* [13] for public consultation. This received comments from different institutions, organizations and scientists, from which a second draft was prepared [13] and made public on August 24, 2018. The latter also underwent public consultation, which ended in November 2018. This article examines the two drafts with their corresponding comments available on the *website* of CDC (https://www.regulations.gov/docket?D=CDC-2016-0001). The analysis considers only the comments from the public, since the comments from peer reviewers asked by the agency are

The antecedent of this draft REL is the existence of a PEL based, in turn, on a 1988 OEL, which controls the exposure to silver in the workplace. The OSHA

and the mandatory exposure limit established in the PEL, refer to silver in larger sizes; no standard exists, be it an OEL or a PEL, for nanosized silver. What is under construction, and is discussed here, is a voluntary guide, a REL. It is important to note that, at the beginning of this process, when NIOSH based the first draft of the REL for silver in nanosize on the existing OEL that referred to silver in larger sizes, implicitly proposed an equivalent regulatory treatment for silver and nanosilver. However, as the consultation process advanced, and critical comments were made on this point, NIOSH responded with a second draft that distinguishes nanoparticles in the air, establishing a much lower maximum exposure of 0.9 μm/m3

soluble compounds. As will be seen, the public consultation evidenced that there are opposing positions regarding whether the OEL for silver is sufficient to elabo-

• *PETA International Science Consortium Ltd* (PISC) is an international consortium aimed at promoting strategies to replace the use of animals in

The commentaries correspond to the following social actors: PISC, PBNS, NIA, CTA, SNWG, Faustman, Oberdörster, and Fox, briefly described in what follows.

• *Pennsylvania Bio Nano Systems* (PBNS) is a one-person company that advises nanotechnology companies regarding technical regulatory matters [16, 19].

• *Nanotechnology Industries Association* (NIA) is an association of companies and other entities related to the production and commercialization of nanotechnology products. It advises national and international institutions and organisms, such as the OECD and the ISO, and has the goal of promoting the use of

• *International Center for Technology Assessment* (CTA) is an NGO oriented to

• *Silver Nanotechnology Working Group* (SNWG) is an enterprise organization that promotes scientific knowledge production and public information regarding the beneficial use of silver nanoparticles in industrial products and

• *Elaine Faustman* is an investigator for the Institute *Risk Analysis and Risk* 

*Communication*, and the *Department of Environmental and Occupational Health* 

for soluble and powdered silver. Both, the OEL study

and

for particles in dust, smoke, and

*DOI: http://dx.doi.org/10.5772/intechopen.96104*

anonymous and not publicly available.

leaving the original exposure limit of 10 μm/m3

rate a REL for nanosilver [11, 17].

experiments [18].

nanotechnologies [20].

final consumption [22].

assess the social impacts of technologies [21].

*Sciences*, at the *University of Washington*, WA [23].

imposes a PEL of 10 μm/m3

#### *AgNano, the Construction of Occupational Health Standards: A Status Update DOI: http://dx.doi.org/10.5772/intechopen.96104*

On December 18, 2015, the NIOSH put out a first REL draft, entitled *Current Intelligence Bulletin: Health Effects of Occupational Exposure to Silver Nanomaterials* [13] for public consultation. This received comments from different institutions, organizations and scientists, from which a second draft was prepared [13] and made public on August 24, 2018. The latter also underwent public consultation, which ended in November 2018. This article examines the two drafts with their corresponding comments available on the *website* of CDC (https://www.regulations.gov/docket?D=CDC-2016-0001). The analysis considers only the comments from the public, since the comments from peer reviewers asked by the agency are anonymous and not publicly available.

The antecedent of this draft REL is the existence of a PEL based, in turn, on a 1988 OEL, which controls the exposure to silver in the workplace. The OSHA imposes a PEL of 10 μm/m3 for soluble and powdered silver. Both, the OEL study and the mandatory exposure limit established in the PEL, refer to silver in larger sizes; no standard exists, be it an OEL or a PEL, for nanosized silver. What is under construction, and is discussed here, is a voluntary guide, a REL. It is important to note that, at the beginning of this process, when NIOSH based the first draft of the REL for silver in nanosize on the existing OEL that referred to silver in larger sizes, implicitly proposed an equivalent regulatory treatment for silver and nanosilver. However, as the consultation process advanced, and critical comments were made on this point, NIOSH responded with a second draft that distinguishes nanoparticles in the air, establishing a much lower maximum exposure of 0.9 μm/m3 and leaving the original exposure limit of 10 μm/m3 for particles in dust, smoke, and soluble compounds. As will be seen, the public consultation evidenced that there are opposing positions regarding whether the OEL for silver is sufficient to elaborate a REL for nanosilver [11, 17].

The commentaries correspond to the following social actors: PISC, PBNS, NIA, CTA, SNWG, Faustman, Oberdörster, and Fox, briefly described in what follows.


*Silver Micro-Nanoparticles - Properties, Synthesis, Characterization, and Applications*

unpredictable and their use may involve unknown risks [2].

produced at a word level [13].

guide (REL) of permissible exposure for AgNP [15].

products until November 2018, present in almost all economic sectors.

Analyzing this discussion required placing nanotechnologies in their historical and socio-technical context. Nanotechnology is the intentional manipulation of matter to form new structures with a dimension smaller than 100 nanometers. Nanoparticles have particular physical–chemical properties (electrical, optical, magnetic, thermal, mechanical) and are different from the same material on a larger scale [1]. The interaction of nanoparticles with biological systems is highly

From mid-2000s there was an explosion of nanotechnology products in the market. Although there are no detailed records, StatNano [3] registered 8 452

The development of this emerging technology coincides with the wake-up call by the World Health Organization and the United Nations Environment Program on the global pandemic caused by toxic chemicals [4]. These organizations indicate that about five million people die annually from the exposure and handling of chemical substances and contact with consumer items that contain them [5, 6]. Silver is a metal known both for its toxicity and for its healing effects since ancient times [7]. Currently, its use in the form of nanoparticles is blossoming. The inventory of nanotechnology products of the *Woodrow Wilson International Center for Scholars* identified 442 using AgNP, and reports that silver is the most commonly used nanomaterial in the whole set of products [8, 9]. The antibacterial properties of AgNP justify its use in textiles, food packaging, paints, toys, environmental technologies, cosmetics, implants, and other medical devices; they are also used in the electronics industry (semiconductor printing, radio frequency identifiers, flexible circuits, solar panels) [10–12]. The United States produced 20 tons of AgNP in 2010; in 2014 between 450 and 542 tons were

Toxic effects of AgNP on the human organism have been detected when certain

The toxicity of silver in larger sizes, when certain exposure limits are exceeded, is already widely known, causing, for example, argyria, and there are safety regulations in this regard [16]. With the increasing use of AgNP, a debate arises about whether, in smaller sizes, such as nanoparticles, the toxicity of silver remains the same, as some of the actors who participated in the public consultation analyzed here argue, or if toxicity manifests itself differently, as other actors claim.

Regarding occupational safety, there are mandatory regulations and voluntary guides. In the United States, a chain of regulations can be identified. The first is the *Occupational Exposure Limits* (OEL), which are scientific studies about the maximum acceptable limit of particles in workplaces of hazardous substances of certain material or class of materials. The OELs are established considering functional categories (exposure period time according to the degree of concentration, maxi-

Based on OEL, mandatory workplace standards called *Permissible Exposure Limit*

(PEL) are developed. These are prepared by the *Occupational Safety and Health Administration* (OSHA). Voluntary standards, such as the Recommended Exposure Limit (REL) examined in this chapter can also be developed, often based on OELs.

mum exposure, and an emergency category when danger is imminent).

exposure levels are exceeded [14]. In the workplace, the AgNP enter the body mainly through inhalation. The final destination within the organism is uncertain. Whereas there was a consensus to consider that were the lungs, more recent research has showed that they can move from the lungs to the liver, and eventually to the spleen and kidneys, accumulating [12], thus exposing workers to a variety of potential health threats. These characteristics of AgNP have raised the concern of CDC of the United States, which has recommended NIOSH to develop a voluntary

**240**

These are elaborated by NIOSH.

