A Tiered Screening Approach to Evaluating Chemical Exposures from

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A Tiered Screening Approach to Evaluating Chemical Exposures from Consumer and Commercial Products Ann Mason, William Greggs, Bryce Landenberger, William Carroll, Brett Howard, and Stephen Risotto ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b00851 • Publication Date (Web): 06 Apr 2018 Downloaded from http://pubs.acs.org on April 7, 2018

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ACS Sustainable Chemistry & Engineering

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A Tiered Screening Approach to Evaluating

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Chemical Exposures from Consumer and

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Commercial Products

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Ann M. Mason1, William Greggs2, Bryce D. Landenberger3, William Carroll4,

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Brett Howard,1 Stephen P. Risotto1* 1

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American Chemistry Council, 700 2nd Street, NW, Washington, District of Columbia 20002 2

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Soleil Consulting LLC, 4195 Dingham Drive Sanibel, Florida 33957 3

8 4

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The Dow Chemical Company, 1803 Building, Midland, MI 48674

Carroll Applied Science LLC, 6519 Spring Valley Road, Dallas, Texas 75254

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The manuscript was written through contributions of all authors. All authors have given approval

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to the final version of the manuscript.

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ABSTRACT: To assess human health risks associated with chemicals, risk assessors often utilize

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models that evaluate the health effects of a chemical constituent based on inherent characteristics

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and the potential for human exposure to the chemical. The complexity of these models, however,

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Corresponding author – [email protected], (202) 249-6727.

ACS Paragon Plus Environment

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ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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makes them difficult to adopt. A simplified, screening-level assessment is needed. Although

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several approaches exist for screening chemical ingredient hazards in consumer and commercial

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products, few exist that allow users to combine this hazard information with exposure potential

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to screen ingredients or products based on risk. In this paper, we propose a tiered approach to

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effectively screen product ingredients using readily accessible public information. This approach

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evaluates hazard using the Globally Harmonized System for Classification and Labelling along

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with environmental persistence and bioaccumulation data. Based on the hazard results, one can

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then assess product ingredients for exposures that may lead to a negative health effects.

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Ingredients that present low hazard, or have minimal exposure levels, are considered low

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priority. For ingredients that do not pass an initial hazard and exposure screen, more

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sophisticated approaches may be used to further evaluate the likelihood and extent of potential

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exposures. Each evaluation tier is designed to be conservative to provide an approach that helps

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to achieve safe use of the product.

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KEYWORDS: hazard, exposure, GHS, safety assessment, chemical ingredient, margin of

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exposure

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INTRODUCTION

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Consumers and retailers increasingly want manufacturers to report information about chemical

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ingredients found in their products, especially those in the home, beauty, and personal care

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aisles. Manufacturers design products to meet customer performance and safety expectations as

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well as retailer specifications. Consumer products generally are composed of many ingredients

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that may be mixed, reacted, and or physically bound to create a final product. Multiple

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ingredients work together to perform various functions in a product designed to meet user


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expectations. As a consequence, the actual health risk posed by the final product often does not

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reflect the hazard associated with a pure ingredient. 1

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The ingredient’s physical and chemical properties, its physical state and concentration in the

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product, and product use patterns can significantly impact the resulting safety concerns

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associated with a constituent ingredient. For example, a substance that presents an inhalation

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hazard in its pure form (e.g., titanium dioxide) may no longer present such a hazard when added

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to a liquid paint formulation.

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Thus, while a hazard score for a chemical substance is important, it is only part of the

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information needed to assess a product’s potential for harm. Only after consideration of how the

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ingredient exists within the product, in addition to the form and use of the final product, can the

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user determine its ultimate release and exposure potential.

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At present, many resources are available to identify2,3,4 and evaluate5,6,7the hazards of chemical

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substances used in manufacturing consumer and commercial products, and a variety of

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approaches are available for quantifying likely exposures to product ingredients.8,9,10,11,12 Few if

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any approaches exist, however, that offer a practical approach to assessing both hazard and

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exposure potential using readily available information to enable rapid ingredient screening for

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safety. 13

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This article outlines a tiered-screening approach intended to supplement hazard evaluations

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derived from common assessment tools. Our method represents input from various stakeholders

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who provided input over several iterations through a collaborative process. We designed this

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method to illustrate how manufacturers, brand owners, and retailers can use publicly available

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information to combine a chemical’s hazard information with common-sense methods for

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assessing potential exposure based on expected product use. By adding simple exposure


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considerations to the hazard information, it is our hope that interested parties can better

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understand the potential for harm associated with a product during use and can work with their

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suppliers to resolve questions about product safety. The approach focuses on exposure as an

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important consideration in assessing product ingredients, but is not meant to replace evaluation

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of ingredients using multiple criteria including end-of-life and other lifecycle considerations. We

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believe that this exposure screening approach, should be viewed as important component of a

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robust product safety evaluation.

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SCOPE AND PURPOSE

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During our interactions with stakeholders throughout the supply chain for commercial and

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consumer products, we witnessed a growing recognition that chemical hazard, while important,

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cannot be the only consideration when selecting product ingredients. That notwithstanding, we

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find a general perception that tools attempting to consider criteria in addition to hazard are

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complex and difficult to interpret. Exposure is arguably the most significant of these criteria,

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which is vital to assess health and safety. Many assessment frameworks include references to

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exposure, but few provide practical guidance for how to consider it. In its 2014 review of

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chemical selection frameworks, the National Research Council (NRC) concluded that

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“simplified exposure estimates without elaborate exposure modeling can meet the needs of many

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alternatives assessments.”14 The NRC’s recommendation inspired our proposed method for

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evaluating exposure potential – and utilizes several screening considerations based on chemical

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properties as well as other product characteristics.

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The tiered screening approach that we describe herein can be applied to many product-related

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ingredients, including intentionally-added chemical ingredients, residuals, by-products, and other

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contaminants, provided the ingredient information exists. One may also use this approach to


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evaluate product uses other than those intended by the manufacturer as long as the parameters of

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such unintended use can be identified.

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METHODOLOGY

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In developing the tiered exposure approach we focused on readily available chemical

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ingredient information that could inform the product evaluation process, beginning with

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ingredient health and environmental hazard information, continuing with physical and chemical

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properties, and ending by considering product use. Together, this information provides a simple

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iterative approach to determine if an ingredient is low concern or if more information is needed

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to assess potential health-related effects associated with the product.

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For an initial review of ingredient hazard, we used the Globally Harmonized System for

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Classification and Labelling (GHS)15 data provided on Safety Data Sheets (SDSs) accompanying

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all chemical shipments. SDSs are generally available on the Internet through a search of the

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chemical name or, if you know the name of the manufacturer or supplier, a visit to that

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company’s web site. Public agencies also compile GHS classification information, including the

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European Chemical Agency (ECHA), which provides a searchable database for all classification

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and labeling information on chemicals offered for sale in Europe.

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Furthermore, since many companies are concerned about the potential for long-term

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environmental effects of product ingredients, we have included persistence and bioaccumulation

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information in the initial hazard screen. These data are often provided on the SDS, but not

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incorporated into GHS classifications. Consequently, we have included persistence and

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bioaccumulation data developed by Environment and Climate Change Canada (ECCC) for

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chemicals on its Domestic Substances List (DSL) in our proposed approach.16 The ECCC


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website hosts this data in a spreadsheet format that can be translated into a format usable in the

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proposed screen.

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To evaluate potential exposure to product ingredients, we consider both the state in which the

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ingredient exists in the product and its physical and chemical properties. This allows us to

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evaluate potential chemical releases, and, if so, whether that release can result in exposure. For

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exposure potential, we consider properties that increase exposure levels through inhalation,

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dermal, or oral pathways. These data also are available on the ingredient SDS or through

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Internet search.

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Assuming exposure occurs for a given product, we needed an approach to evaluate the extent

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and severity of the exposure, while considering user characteristics and product use. Although

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quantitative information on these parameters may be available, we designed the approach to

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work with qualitative information that users can estimate. This screening approach will

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contextualize potential exposures, allowing users to accurately gauge product risk quickly and

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effectively.

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Figure 1. Tier 1: Hazard Screen

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Tier 1: Initial Hazard Screen

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Using the chemical ingredients for a finished product, under Tier 1 a user considers the GHS

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information for human and environmental hazards for the substances along with their persistence

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and bioaccumulative properties to identify substances that may present an exposure concern. The

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eleven GHS hazard categories for this tier include carcinogenicity, germ cell mutagenicity,

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reproductive toxicity (including developmental effects), acute toxicity, systemic toxicity–single

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exposure, systemic toxicity–repeated exposure, skin irritation, skin sensitization, eye irritation,

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respiratory sensitization, and aquatic toxicity.

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As proposed, ingredients without a classification for human or environmental health of 1, 2, or

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3 under GHS and that are not identified as persistent or bioaccumulative by ECCC are

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considered low concern and require no further assessment (Figure 1). This aligns with the intent


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behind a screening approach, which is to prioritize and focus resources in areas that pose the

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greatest concern. Thus, while the absence of a GHS classification does not provide a conclusive

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result, it allows for an initial screening based on easily accessible information without the need

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for independent toxicological analysis. This method is similar to the low-toxicity screens used in

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the other approaches described earlier. Users may wish to consult sources beyond their own

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suppliers – such as the ECHA data base17 – to confirm GHS classifications during initial hazard

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screening. We have included eleven of the GHS health and environmental health endpoints for

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the initial hazard screen in our approach, but users have the option to focus on a subset of GHS

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endpoints, set different thresholds for GHS classifications, or include other criteria (e.g.,

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flammability, reactivity) important to them.

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If the Tier 1 hazard screen indicates that the product ingredient is not low concern, the user

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may then advance the ingredient to Tier 2 to assess its potential for release from the product. For

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some ingredients, however, the user may decide that the hazard is not acceptable and choose to

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conclude the assessment.


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Figure 2. Tier 2 Step A: Physical State Screen

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Tier 2: Physical State and Chemical Property Screen

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The Tier 2 exposure screening consists of two steps: Step A considers the physical state of the

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ingredient in the product (Figure 2) and Step B considers, common ingredient chemical and

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physical properties (Figure 3). Each property can impact the release potential from the product

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that could result in exposure.

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Step A – Physical State Screen. The physical state of the ingredient within the product

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determines whether the chemical is available for release during use of the product. Step A of Tier

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2 considers four possible situations where an ingredient’s hazardous properties may be of lesser

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concern given how the ingredient is used in a product (Figure 2); other situations may exist.

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The first situation is when the ingredient is involved in a chemical reaction (i.e., a change in

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molecular or ionic structure) in the production of the product such that it no longer exists in its


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original (hazardous) form. The use of a monomeric substance to produce a polymer (e.g.,

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ethylene to polyethylene) is an example of such a chemical reaction where the molecular

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structure of the raw ingredient has changed and the resulting material no longer exhibits the

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initial properties of the ingredient. Residual levels of the monomer may exist within the polymer,

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although typically at very low concentrations. As a result, any hazard present from residual

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monomer is likely to be low as indicated by exemptions established by the federal Environmental

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Protection Agency (EPA) and Food and Drug Administration.18,19 Nevertheless, in certain uses,

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further exposure assessments may provide additional assurances.

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The dissolution of one ingredient into other components of the product results in a phase

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transition, colloid, or change in physical state (from solid to liquid) that can impact the

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manifestation of the hazards presented by the ingredient. A material deemed hazardous by

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inhalation of its finely divided solid form presents an entirely different (and more benign) hazard

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when suspended in a liquid. One often used example is the mineral titanium dioxide which exists

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as a powdery solid after processing and is used as a pigment in paints and a variety of consumer

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and industrial products. While an inhalation hazard in its powder form, this exposure route is

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eliminated when the mineral is suspended in a paint or other liquid product formulation.20

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The physical binding of an ingredient in the product can also alter its release and exposure

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potential. One illustrative example can be found in the distinction between the friable and

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nonfriable forms of asbestos. Friable asbestos is a term that describes any asbestos containing

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material that, when dry, can be easily reduced to powder by hand – resulting in the release of

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asbestos fibers that can cause lung disease.21 Asbestos that cannot be easily crushed into powder

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is considered non-friable asbestos (e.g., legacy uses in resilient floor covering, asphalt roofing)

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where the asbestos fibers are bound within the product and less likely to be released. While the


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potential for fiber release from non-friable materials remains, the circumstances of any release

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are very different than for the friable state. In such a case, the assessment requires consideration

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of exposure over time – resulting from physical wear of the product that would potentially

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release small amounts of fiber over time. A similar concern may exist for ingredients added to

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polymeric materials that are physically, but not chemically, bound in the material (e.g.,

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plasticizers).

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Moreover, some products will be subject to abrasion and/or degradation resulting in particulate

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or vapor formation or other evidence of wear and aging. If the chemical is likely to be released

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(or if there is evidence of release) through these mechanisms, or if the potential for wear and

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aging are unknown, release and subsequent human contact should be anticipated and the analysis

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should proceed to Tier 2 Step B.

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Physical barriers may prevent chemical movement or migration, altering potential exposure. If

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properly designed, barriers can encase vapors, liquids, and solid chemicals within a product and

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prevent or minimize release. Examples include the full material encapsulation, such as in a

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sealed car battery; gases or liquids encased in canisters; and products behind walls, such as

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insulation or electrical wiring. Similar to physical ingredient binding, consideration should be

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given to whether the ingredient may be released over time during normal use applications.


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Figure 3. Tier 2 Step B: Chemical Property Screen

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Step B – Chemical Property Screen. Following the Step A determination that a chemical can be

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released from the finished product, Step B considers the ingredient’s physical and chemical

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properties to better evaluate its potential for exposure. Human exposure occurs through

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inhalation, dermal, or oral routes, and each exposure pathway requires evaluation (Figure 3).

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Step B adopts common physical-property triggers to identify these exposure potentials, and the

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screen considers the following properties:

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1. The potential for inhalation is related to chemical volatilization or particulate size.

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Volatilization, and inhalation, is unlikely if:

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the chemical’s vapor pressure (VP) is less than 10-6 mm Hg (per EPA22)AND its

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boiling point(BP) is greater than 380 to 400 degrees Celsius (oC) (per World Health

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Organization (WHO)23 and Berkley Lab24), OR


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•

the product does not have the potential to generate inhalable particulates of 100

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micrometer (µm) (per the American Conference of Governmental Industrial

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Hygienists25) or greater in size during use, aging, and wear.

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2. The potential for dermal exposure correlates to chemical absorption. Absorption is

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unlikely if:

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•

greater than 4 (per EPA,26 the European Commission,27 or WHO28) AND

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the chemical’s Octanol-Water Coefficient (log Kow, often referred to as log P) is

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its molecular weight (MW) is greater than 500 (per the Organization of Economic Cooperation and Development).29

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3. The potential for oral contact is defined by whether (a) the product containing the

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material is likely to be put in the mouth during anticipated normal use (e.g., mouthing

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of toys by infants), or (b) there is evidence to suggest that the ingredient can be

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released from the product and can accumulate in dust that may result in hand-to-mouth

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exposure. In most cases, oral contact can be evaluated through observation and

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knowledge of the product and user behavior. Oral exposures can also result indirectly

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from food contact with the product.

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If the potential for inhalation, dermal, and oral exposure is low, then exposure is unlikely and

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the ingredient can be considered of an overall lower concern that does not require further

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evaluation. If, on the other hand, exposure is possible from any of these routes or the information

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is unavailable related to an exposure pathway of concern, the screening evaluation may proceed

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to consideration of the product’s use in Tier 3.

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Tier 3. Product Use Screen


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Tier 3 uses a matrix approach to consider exposure potential based on intended product use, its

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form and other factors (Table 1) in conjunction with the chemical’s hazard level (Figure 4). We

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developed sub-scores for both hazard and exposure potential and combined in the matrix to

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develop an overall Product Use Score for this tier.

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To start the Tier 3 screen, the analyst uses a description of the final product and its intended

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use to guide the responses to Product Use Scoring Matrix. To determine exposure potential, the

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analyst scores five areas (Table 1) and calculates an exposure sub-score.

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•

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First, the nature of the Product User, that considers the potential sensitivity to chemical exposure from Children/Sensitive populations to Professionals (e.g., installers).

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Second, the Form of the Product during use that considers those with the highest

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potential for exposure (i.e., Aerosol/Pump/Powder), to those with the lowest (i.e.,

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Solid).

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•

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concentration ranges from high (i.e., >10%) to low (i.e.,

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