Chemicals Alternatives Assessment (CAA): Tools for Selecting Less Hazardous Chemicals
Authors: Whittaker Margaret H. , Heine Lauren G. 
Published: June 2013

Chemicals alternatives assessment (CAA) is a form of alternatives assessment that focuses on finding alternative chemicals, materials or product designs to substitute for the use of hazardous chemicals. Chemical hazard assessment (CHA) or comparative CHA is a method for comparing chemicals based on their inherent hazard properties. CAA is inclusive of CHA. However, a comprehensive CAA can be much broader and include information such as cost, availability, performance and social and environmental life‐cycle attributes. CHA/CAA provides users with hazard‐based information to make informed decisions when selecting less hazardous chemical alternatives. There are multiple CAA methods in use around the world and these methods share a common goal, namely, to support the intelligent design, use and substitution of chemicals to benefit humankind in a manner that will not harm our environment and its inhabitants. Ideally, a CAA/CHA will completely characterize a chemical's intrinsic human health and environmental hazards, in the process promoting the selection of less hazardous chemical ingredients, in addition to avoiding unintended consequences of switching to a poorly characterized chemical substitute.
CHA methods typically share common hazard endpoints related to human toxicity, environmental toxicity and environmental fate. The endpoints are evaluated based on criteria that allow for the use of measured or predicted data. Human health criteria in CHA evaluate endpoints such as potential carcinogenicity, mutagenicity, reproductive and developmental toxicity, endocrine disruption, acute and chronic or repeat dose toxicity, dermal and eye irritation and dermal and respiratory sensitization. Acute and chronic aquatic toxicity, terrestrial toxicity, persistence and bioaccumulation are commonly evaluated to predict a chemical's environmental toxicity and fate. Finally, some CHAs (such as GreenScreen™) also evaluate a chemical's physical characteristics such as flammability and reactivity.
Of the CAA methods listed, only the US Environmental Protection Agency (EPA)'s DfE program, CPA's GreenScreen™ and MBDC's Cradle to Cradle® paradigms are fully transparent and publicly available methods of assessment. Most other CAAs in use around the world do not fully disclose all of their reasoning or resources used for establishing threshold values for hazard criteria, prioritization of hazard endpoints and life‐cycle concerns. Some CAA methods are limited to a focus on CHA whereas others such as MBDC's Cradle to Cradle® expand the focus to consider some life‐cycle attributes. Whether the CAA method includes additional attributes or not, CHA can be used in a modular way, combining with other needed information to inform decision‐making.
CAA provides a powerful means to improve upon the status quo by establishing methods to inform chemical substitution in a scientifically rigorous and defensible manner. Recognizing the value of CAA and fostering greater adoption of CAA methods provide stakeholders with much‐needed tools to address a serious deficiency in the way in which chemicals are used in society, as maintaining the status quo is analogous to giving up. As humankind's understanding of the full costs and benefits of chemicals matures, it is critical that we cease using those chemicals that can permanently impair human health or the environment.