TSCA and Exposure Assessment: Overview - 58tinton.win

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Friday, August 11, 2017

TSCA and Exposure Assessment: Overview

While I was revising my SHM 477: Environmental Management course for the next academic year, I found myself overwhelmed by the volume of information about the changes to the Toxic Substances Control Act (TSCA). There is a slew of information out there, most of it by the U.S. Environmental Protection Agency, but it is strangely structured and not all of it is user-friendly. Hence, this post and the series that will follow on TSCA.

The revised regulations for Toxic Substances Control are found in Chapter 53 of Title 15, and the text of the new requirements is in Subchapter I, �Control of Toxic Substances.� 

15 CFR 53 Part 2601(a) explains the focus of Subchapter I, �Control of Toxic Substances,� to be on chemical substances and mixtures that are manufactured, processed, distributed in commerce, used, or disposed, and which �may present an unreasonable risk of injury to health or the environment.�

Unreasonable� is the key word here, and it is not defined. All the regulation says is that the Administrator (of the U.S. Environmental Protection Agency) will determine whether a chemical poses an unreasonable risk based on scientific information or testing. In Part 2603(b), it expounds upon what could be considered an unreasonable risk: health and environmental effects including carcinogenesis, mutagenesis, teratogenesis, behavioral disorders, cumulative or synergistic effects, and any other effect that could present an unreasonable risk of injury to health or the environment.

By this definition, were you to bottle sunlight as a new chemical product, it could easily constitute an unreasonable risk, due to the ultraviolet radiation and potential for cancer.

This regulation puts into policy a requirement for the development of adequate information about the health and environmental effects of chemical substances and mixtures, and places the responsibility for developing this information on the manufacturers and processors of chemical substances and mixtures per 15 CFR 53 Part 2601 (b)(1).

The key word in this section is �adequate� � who decides whether the information provided by a manufacturer is adequate? How do they think manufacturers and distributors will find the funding, technical specialists, and content experts to develop this information? Many manufacturers are still not in compliance with the 29 CFR 1910 Part 1200 Hazard Communication requirements � many Safety Data Sheets (SDS) in circulation today do not meet the requirements or intent of the standard.

The Administrator (of the U.S. Environmental Protection Agency) is responsible for considering the environmental, economic, and social impacts of actions associated with TSCA. This is a strange statement, and puts the Administrator and the U.S. Environmental Protection Agency in an unenviable position of trying to please everybody.

Some interesting definitions for industrial hygienists and safety professionals to consider:
  • �Conditions of use� means the circumstances [�] under which a chemical substance is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used, or disposed of.
  • �Environment� includes water, air, and land and the interrelationship which exists among and between water, air, and land and all living things.
  • Health and safety study� means any study of any effect of a chemical substance or mixture on health or the environment or on both, including underlying information and epidemiological studies, studies of occupational exposure to a chemical substance or mixture, toxicological, clinical, and ecological studies of a chemical substance or mixture, and any test performed pursuant to this chapter.
  • Potentially exposed or susceptible subpopulation� means a group of individuals within the general population [�] who, due to either greater susceptibility or greater exposure, may be at greater risk than the general population of adverse health effects from exposure to a chemical substance or mixture, such as infants, children, pregnant women, workers, or the elderly.

One item of concern is the definition of �health and safety study� � it does not seem to require that the stud(ies) be peer-reviewed to be used, per the definition. Does this mean the U.S. EPA is encouraging and will support citizen science? How will the submitted studies be evaluated for scientific accuracy and validity?

Part 2625(h), �Scientific Standards� provides some clarification:
  • The Administrator will make a decision based on science (always a good thing)
  • The Administrator will use scientific information, technical procedures, measures, methods, protocols, methodologies, or models [�] consistent with the best available science
  • The Administrator will consider the extent to which the scientific information, technical procedures, measures, methods, protocols, methodologies, or models are REASONABLE, CONSISTENT with, and RELEVANT for the intended use of the information
  • The data, assumptions, methods, quality assurance, and analyses employed must be documented and will be evaluated for clarity and completeness
  • The variability and uncertainty of the procedures, measures, methods, protocols, methodologies, or models will be evaluated and characterized
  • The �extent of independent verification or peer review� for the procedures, measures, protocols, methodologies, or models will be evaluated
  • The Administrator will make decisions based on the �weight of the scientific evidence�

This language is troublesome and does not appear to require peer reviewed science. As William Watt said: �Do not put your faith in what statistics say until you have carefully considered what they do not say.� Results can be manipulated using complex statistical analyses until they say (or do not say) whatever the authors� hypothesis may have been.

Simon Oxenham at Big Think (#bigthink) explored this in an article entitled �Believe It Or Not, Most Published Research Findings Are Probably False.� He gave a quick synopsis of key things for scientists to consider:
  • The smaller the study, the less likely the findings are to be true.
  • The smaller the effect size, the less likely the findings are to be true.
  • The greater the number and the lesser the selection of tested relationships, the less likely the findings are to be true.
  • The greater the financial and other interests and prejudices, the less likely the findings are to be true.
  • The hotter a scientific field, the less likely the findings are to be true.

The last two points are especially worrisome for the state of exposure assessment today � there are significant costs associated with determining the exposure concerns for TSCA, and there is a lot of money involved in developing newer, faster, and more specialized tests for chemicals. There is such potential for bias and lazy or incomplete science with the explosion of interest in occupational and exposure science, and recognizing this seems to be up to each individual industrial hygienist or safety professional.

A similar concept was explored by Derek Muller at Veritasium (#veritasium) in a video entitled �Is Most Published Research Wrong?� It�s a good video to watch if you�re too busy to read the Big Think article.

In my next post, I�ll go over the testing requirement for chemical substances per TSCA. Future posts are planned to include the following topics:
  • Testing of chemical substances
  • Manufacturing and protection against unreasonable risks
  • Risk evaluation in TSCA
  • Imminent hazards in TSCA
  • Reporting requirements of TSCA
  • Research aspects of TSCA
  • How TSCA handles confidential information
  • Citizen�s civil actions and petitions in TSCA
  • Employee protection and TSCA effects on employment
  • How test methods will be developed and evaluated for TSCA
  • ReachScan: the exposure assessment model
  • Using predictive methods to assess exposure
  • New chemical exposure limits under TSCA

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