Many standards and regulations include wording like “may not contain X” or “may not use X,” where X is the substance to be excluded. We will call this concept “zero tolerance.” We can detect lower and lower levels of materials of concern, be it particles, compounds, or elements. Zero is related to the sensitivity of the method used for determination. As methods become more sensitive, the relevance and practicality of the ever-decreasing amounts of X being excluded becomes significant.
The concept of zero tolerance finds its way into performance requirements and acceptance criteria. Examples include chemical purity, industry-wide requirements, and allowable residue. Zero tolerance is found in company-wide mandates, governmental standards, certification requirements, industry specifications, worker safety requirements, as well as neighborhood and global safety/environmental requirements. Coping with the implications of zero tolerance impacts product safety and performance and manufacturing costs. It is helpful when a document either defines an analytical method for determining zero or sets a de minimis level.
HCFC-225 ban
One good, recent example is the way the U.S. EPA has proposed to define the phase-out or ban of HCFC-225. HCFC-225 has become a staple for certain critical cleaning applications for a number of reasons. It is similar to the wistfully-remembered CFC-113, in that it provides moderate solvency, can be effective in removing particles, is readily redistilled, is not considered a VOC, and has a relatively favorable worker exposure profile. However, like CFC-113, HCFC-225 is an ozone depleting compound (ODC); and when it was introduced in the late 1980s, it was considered to be an interim replacement. Nearly a quarter of a century later, (in the U.S. and given the legislative constraints of The Clean Air Act) non-refrigerant usage bans are set for Jan. 1, 2015.1
For HCFC-225, the concept of “ban” includes some aspects of the words “no” or “can’t”, particularly in terms of production and sale of new material. However, in terms of use of existing material, there have been varying and changing positions.
Previously, the EPA had indicated that beginning Jan. 1, 2015, HCFC-225 could be used only if it were used or recycled or was already in a product that is the final container for use, such as in an aerosol.2 This approach was taken based on exceptions in Section 605(a) of the Clean Air Act. However, use of virgin, stockpiled HCFC-225 would not be allowed. The implications would have been that HCFC-225 could be directly sprayed into the air from an aerosol can, but could not be used in a well-contained solvent cleaning system. The approach of allowing aerosols to the exclusion of a contained system seems to us to defeat the spirit, if not the letter, of the Clean Air Act. Disallowing the use of stockpiled virgin HCFC-225 would very likely lead companies to go through the exercise of using the material once, and then store it as recycled material.3
However, a recent EPA proposal4 would allow usage for existing stockpiles by invoking a de minimus exception. The concept of de minimis in this case implies not necessarily a very low level of the chemical in question, but rather a non-worrisome level relative to the risk involved and relative to other options that might be considered.
Worker and community exposure
Many chemicals used in manufacturing, including those crucial for critical cleaning, contamination control, and product quality, are subject to worker exposure limits. In the past few years, many of these limits seem to be asymptotically approaching zero.
Manufacturers are faced with the task of considering increased engineering controls, worker monitoring, and substitution of other chemicals. Howard Spielman, Certified Industrial Hygienist and President of Health Science Associates in Los Alamitos, Calif., has concerns with the current risk assessment approach in the U.S. “Some health agencies look at primarily animal studies and at any documented human experience. Using a hierarchy of uncertainty factors, they recommend worker exposure levels that are 10 to 100 times lower than what we have currently.”
Spielman explains that if the higher levels were not sufficiently protective, we should have been seeing effects in the worker population. “We would have expected to see demonstrable epidemiology. Instead, we see people setting standards that approach a zero exposure.” In urging that agencies develop a reality check regarding worker and community exposure limits, Spielman has been known to quip, “Where are the bodies?” He adds that he would rather see industry feel free to use chemicals with well-known toxicology controlled within existing well-documented exposure limits. “The establishment of exceedingly low exposure limits typically results in substitution using chemicals for which there is little toxicological history. For example, changing from a known liver toxin with an exposure limit we know prevents such harm to a substance we know much less about—such as only how much it takes to make you dizzy.”
Stop worrying
In some instances, a group, agency, or entity may claim zero tolerance for a particular chemical. As analytical techniques become ever more sensitive and specific, reaching zero or undetected becomes more and more difficult. What happens when a low level of an undesirable material is found? Some people simply make a de minimus assertion that the level is insignificant or non-troublesome. However, the opinion of one individual or even of one large company may not be compelling against a standard of “may not contain X.” One approach is to use industry standards. Many zero tolerance agencies encourage the use of industry standards. Industry standards can provide specifics to decide when to stop worrying. For example, ASTM standards are consensus-based; and the rationale is typically relatively transparent. If there are no industry standards for a particular analyte, a risk/benefit analysis may be allowable.
Unequal standards
Some industry standards are better than others. An industry standard may not be up to date. A standard may be passed along from one generation of committee members to the next, and a flaw in reasoning may get past everyone involved. A reasonable standard should contain methods of detection as well as guidelines for interpreting measured quantities, for establishing de minimus levels. Helping in putting together a reasonable consensus standard will provide clarification and save time in the long run.
References
1. http://www.epa.gov/ozone/title6/phaseout/hcfcuses.html
2. M. Sheppard, “Alternative Cleaners: An Update from EPA’s Significant New Alternatives Policy (SNAP) Program,” Presentation at Parts Cleaning Expo (PCx), April 2013.
3. E. Kanegsberg, “EPA Changes Direction—Again,” Clean Source, The BFK Solutions Newsletter, Jan. 2014.
4. Proposed HCFC Allocation Rule for 2015-2019, Proposed Dec. 24, 2013 in the Federal Register. Comments close Feb. 24, 2014. Scroll to “What is EPA proposing for existing inventory of HCFC-225ca and HCFC-225cb?” http://1.usa.gov/1l09TqR
Barbara Kanegsberg and Ed Kanegsberg (the Cleaning Lady and the Rocket Scientist) are experienced consultants and educators in critical and precision cleaning, surface preparation, and contamination control. Their diverse projects include medical device manufacturing, microelectronics, optics, and aerospace. Contact: [email protected]
This article appeared in the February 2014 issue of Controlled Environments.
