Chemtronics Reducing Exposure to Toxic Cleaners with Replacement Solvents

Reducing Exposure to Toxic Cleaners with Replacement Solvents

N-Propyl Bromide (nPB), Trichloroethylene (TCE), Perchloroethylene (Perc) and methylene chloride (MeCl) are examples of toxic chemicals that are commonly used in industrial applications as aerosol cleaners, in vapor degreasers, ultrasonic cleaning equipment, and immersion cleaning. They are commonly used as cleaners because they are non-flammable, have high solvency, and are relatively inexpensive. Because of the toxic nature of these products, the regulatory and liability pressure to identify replacement chemistries is more intense than ever.

Chemtronics has engineered the Tri-VTM high performance cleaning solvents to be a safer replacement for n-propyl bromide and other toxic solvents. Tri-V is formulated with trans 1,2-dichloroethylene (trans-DCE) and does not contain nPB, TCE, Perc, MeCl, or any other hazardous air pollutants (HAP). The following is an overview, history and likely trends for the currently available toxic industrial cleaners, and the data that supports Tri-VTM as a viable, safer alternative.

Identifying Toxic Solvent Cleaners of Concern
The first step to replacing these toxic solvents is identification, which may seem complicated, but can be simplified with a little guidance. Ingredients are referenced either by a variety of chemical identifiers, trade names, or CAS numbers. The Global Harmonized System (GHS) provides a pictogram to help quickly identify potential carcinogens, reproductive toxicity, acute toxicity and other serious health hazards (see pictogram to the right). 

The definitive way to identify the solvent in questions is the CAS number, which is stated on the product label and Safety Data Sheet (SDS). Below is a list of common chemical names for the toxic industrial solvents, and CAS numbers:

Trichloroethylene (TCE), Perchloroethylene (Perc) and methylene chloride (MeCl)

The prevalent use of TCE, Perc, and MeCl has decreased significantly from the time they were approved as substitutes for the ozone depleting substances (ODS), because of concerns with toxic exposure and ground water contamination. In a study of Perc exposure on rats and mice conducted by the US National Toxicology Program (NTP), exposure from 200 ppm and above resulted in hepatic congestion, liver lesions, and mitotic alterations (changes in how cells divide), while some in the high-dose groups died before the study was completed.1

There are also reported incidents of workers being hurt from exposure to these chemicals with some resulting in death. OSHA has linked 50 worker fatalities related to methylene chloride exposure. Two successive deaths, one in September 2011 and the other in February 2012, have prompted OSHA/NIOSH to issue a hazard alert. In both cases “a worker using a product containing methylene chloride” to refinish a bathtub succumbed to the toxic levels associated with an enclosed space and a poorly ventilated work area.2

In response, state and federal agencies set exposure limits to protect workers. OSHA has set the permissible exposure limit (PEL) to 100 ppm for Perc and TCE and 25 ppm MeCl.3 An agency of CDC, the National Institute for Occupational Safety and Health (NIOSH) lists Perc as a potential occupational carcinogen and MeCl as an occupational carcinogen. It advises the “lowest feasible exposure” for both and recommends an exposure limit (REL) of 25 ppm for TCE. 4 California Occupational Safety and Health Standards Board (OSHSB) has regulated the workplace PEL to 25 ppm for Perc, TCE, and MeCl. 5 The professional association for industrial hygienists known as the American Conference of Governmental Industrial Hygienists (ACGIH) has recommended a threshold limit value (TLV) of 10 ppm for TCE, 25 ppm for Perc, and 50 ppm for MeCl.6

Without exception, the NTP classifies TCE, Perc, and MeCl as “reasonably anticipated to be human carcinogen.”7 TCE, Perc, and MeCl are listed as carcinogens under California Prop 65.8 Perc is also an animal carcinogen by ACGIH.9 Under the Safe Drinking Water Act, EPA restricted the maximum contaminant level (MCL) to 0.005 mg/L (5ppb) for TCE, PCE and MeCl.10

While these toxic solvents are still being used in industrial environments, the trend has been to move to alternatives, of which nPB was commonly considered a viable alternative.

n-Propyl Bromide (nPB)
During the phase-out of class I ODS in the 1990’s, nPB was relatively new to the US industry. nPB did not have a history of widespread use, so was not regulated. Its unregulated status made it an attractive alternative to the heavily regulated solvents like TCE, Perc and MeCl, with some formulators marketing it as a “safety solvent”. Even now, there is no exposure limit set by OSHA or NIOSH.

However, there are cited examples in the industry where workers suffered major health effects when exposed to nPB. The following is a case reported to regional poison control centers in Pennsylvania (2007) by attending physicians who treated the affected workers, and later investigated by federal and state health agencies.

“In 2007, a male aged 50 years visited an emergency department in Pennsylvania with a history of
confusion, dysarthria [unclear speech], dizziness, paresthesias [tingling], and ataxia [loss of full
body control] for 24--48 hours. The patient had worked for 8 years at an electronics plant in
Pennsylvania, where for 3 years 1-BP [nPB] had been used to clean circuit boards by vapor and
immersion degreasing... One week after the patient went to the emergency department, the
Occupational Safety and Health Administration (OSHA) evaluated his workplace and found a 1-BP
concentration of 178 ppm by short-term area air sampling... His peripheral neuropathy and ataxia
persisted 1 year after the initial visit. The patient also reported having trouble maintaining mental
focus and stopped working at the electronic plant because of continuing medical problems.”11

While federal agencies have been slow in regulating nPB, CA OSHSB has a PEL of 5ppm and listed it as a developmental/reproductive toxicant under Prop 65. Pennsylvania has included it on its hazardous substance list.12 ACGIH has listed the TLV for nPB as 10 ppm, but there is a proposal to decrease it to 0.1 ppm.13 Comparable to TCE, PCE, and MeCl in toxicity, nPB has been determined by NTP as “reasonably anticipated to be a human carcinogen.”14

Though nPB is listed in Significant New Alternatives Policy (SNAP) under the Clean Air Act, it actually has an ozone depleting potential (ODP). It is also likely to be designated as an air toxin by the EPA. In October 2010 the Halogenated Solvents Industry Alliance petitioned EPA to list nPB as a HAP. New York State followed with its own petition in November 2011. The petitions must undergo a completeness review followed by a technical review. As of Feb. 6, 2015, the petitions passed the completeness review. NPB has taken the first step in joining TCE, Perc, and MeCl as HAPs and subject to regulation by the National Emission Standards for Hazardous Air Pollutants (NESHAPs).15

Chemtronics Tri-VTM High Performance Solvents
In contrast, Tri-VTM does not exhibit any of the health issues associated with nPB, TCE, Perc, and MeCl. A 14-week NTP study in which rats and mice were fed microcapsules with 45% trans-DCE (key active ingredient of Tri-VTM) at a maximum concentration of 50,000 ppm did not result in deaths. More significantly, there were no adverse effects observed in the histopathology and clinical chemistry data.16

In another study, rats were exposed to air containing 200 ppm trans-DCE for 8 hours/day, 5 days/week for 16 weeks. Again, results of the study found no statistically significant changes in clinical chemistry, hematology, or histopathology of the animals.17

Because of these and other studies, Tri-VTM has a high exposure limit of 200 ppm based on standards from OSHA, NIOSH and ACGIH. Due to the overwhelming, negative environmental impact and health risks associated with the nPB, TCE, Perc, and MeCl, Tri-VTM offers a favorable contrast as an overall safer chemical. The positive impact on the atmosphere, environment, and workers’ safety, in addition to comparable cleaning performance, positions Tri- VTM as a viable alternative for industrial solvent cleaning.

Chart 1: health & safety comparison of cleaning solvents

Chemtronics®, a division of Illinois Tool Works (ITW), is the acknowledged industry leader in solutions for the electronics, telecommunications and critical environments markets. Products are engineered to meet a full array of cleaning, protecting, repairing, and PCB prototyping needs. Products include degreasers, flux removers, conformal
coatings, solder mask, desoldering braid, board repair pens, cleanroom swabs and wipes, and fiber optic cleaners.
For more information, go to www.chemtronics.com.

Sources:

1. EPA, “Toxicological Review of Tetrachloroethylene (Perchloroethylene)”, Feb. 2012,
   https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/0106tr.pdf
2. OSHA/NIOSH, “Hazard Alert: Methylene Chloride Hazards for Bathtub Refinishers”,
   https://www.osha.gov/dts/hazardalerts/methylene_chloride_hazard_alert.pdf
3. Toxics Use Reduction Institute (TURI), “Massachusetts Chemical Fact Sheet: Perchloroethylene (PCE)”, July 2007,
   http://www.turi.org/TURI_Publications/TURI_Chemical_Fact_Sheets/Perchloroethylene_PCE_Fact_Sheet/PCE_Details/PCE-Fact-Sheet-pdf “Massachusetts Chemical Fact Sheet: Trichloroethylene (TCE)”, 2008 http://www.turi.org/TURI_Publications/TURI_Chemical_Fact_Sheets/Trichloroethylene_TCE_Fact_Sheet/Printable_Trichloroethylene_TCE_Fact_Sheet “Massachusetts Chemical Fact Sheet: Methylene Chloride”, 2014, http://www.turi.org/TURI_Publications/TURI_Chemical_Fact_Sheets/Methylene_Chloride_Fact_Sheet/Fact_Sheet_Methylene_Chloride.2014
4. Ibid: TURI, “Massachusetts Chemical Fact Sheet: Methylene Chloride” OSHA, “Reducing Worker Exposure to Perchloroethylene (PERC) in Dry Cleaning”, 2005,  https://www.osha.gov/dsg/guidance/perc.pdf Agency for Toxic Substances and Disease Registry (ATSDR), “Public Health Statement: Trichloroethylene” October 2014,
   http://www.atsdr.cdc.gov/ToxProfiles/tp19-c1-b.pdf
5. State of California Department of Industrial Relations, “Permissible Exposure Limits for Chemical Contaminants: Table AC-1”, https://www.dir.ca.gov/title8/ac1.pdf)
6. National Toxicology Program (NTP) / Department of Health and Human Services, “Report on Carcinogens, Thirteenth Edition: Dichloromethane”, https://ntp.niehs.nih.gov/ntp/roc/content/profiles/dichloromethane.pdf Ibid: TURI, “Massachusetts Chemical Fact Sheet: Trichloroethylene (TCE)” “Massachusetts Chemical Fact Sheet: Perchloroethylene (PCE)”
7. Ibid: NTP, “Report on Carcinogens, Thirteenth Edition: Dichloromethane” “Report on Carcinogens, Thirteenth Edition: Tetrachloroethylene”, http://ntp.niehs.nih.gov/ntp/roc/content/profiles/tetrachloroethylene.pdf “Report on Carcinogens: Monograph on Trichloroethylene”, Jan. 2015, http://ntp.niehs.nih.gov/ntp/roc/monographs/finaltce_508.pdf
8. OEHHA, “The Proposition 65 List”, http://oehha.ca.gov/proposition-65/proposition-65-list
9. Ibid: TURI, “Massachusetts Chemical Fact Sheet: Perchloroethylene (PCE)”
10. EPA, “Safe Drinking Water Act: Frequent Questions”, https://safewater.zendesk.com/hc/en-us/articles/212075597-4-What-are-EPA-s-drinking-water- regulations-for tetrachloroethylene- https://safewater.zendesk.com/hc/en-us/articles/212075407-4-What-are-EPA-s-drinking-water-regulations-for-trichloroethylene-
    https://safewater.zendesk.com/hc/en-us/articles/212076937-4-What-are-EPA-s-drinking-water-regulations-for-dichloromethane-

11. CDC, “Neurologic Illness Associated with Occupational Exposure to the Solvent 1-Bromopropane”, 2008, http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5748a2.htm

12. Ibid: OEHHA, “The Proposition 65 List”
13. TURI, “Massachusetts Chemical Fact Sheet: n-Propyl Bromide”, http://www.turi.org/TURI_Publications/TURI_Chemical_Fact_Sheets/n- Propyl_bromide/n-Propyl_bromide_Fact_Sheet
14. NTP, “Report on Carcinogens, Thirteenth Edition: 1-Bromopropane”, http://ntp.niehs.nih.gov/ntp/roc/content/profiles/bromopropane.pdf
15. EPA, “Petition To Add n-Propyl Bromide to the List of Hazardous Air Pollutants”, Feb. 2015, https://www.federalregister.gov/articles/2015/02/06/2015- 01705/petition-to-add-n-propyl-bromide-to-the-list-of-hazardous-air-pollutants
16. NTP, “NTP Technical Report on the Toxicity Studies of trans-1,2-Dichloroethylene”, April 2002, https://ntp.niehs.nih.gov/ntp/htdocs/st_rpts/tox055.pdf
17. EPA, “Toxicological Review of cis-1,2-Dichloroethylene and trans-1,2-Dichloroethylene”, Sept. 2010, https://cfpub.epa.gov//iris/iris_documents/documents/toxreviews/0418tr.pdf
18. United Nations, “Compilation of Technical Information On The New Greenhouse Gases and Groups of Gases Included in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change”, July 2010, http://unfccc.int/national_reports/annex_i_ghg_inventories/items/4624.php
19. United Nations, “2002 Report of the Solvents, Coatings and Adhesives Technical Options Committee (STOC)”, page 79, 2003

20. EPA, “Protection of Stratospheric Ozone: Listing of Substitutes for Ozone-Depleting Substances-n-Propyl Bromide in Adhesives, Coatings, and Aerosols”, May 2007, https://www.federalregister.gov/articles/2007/05/30/E7-9706/protection-of-stratospheric-ozone-listing-of-substitutes-for-ozone-depleting- substances-n-propyl

21. K. O. Patten and D. J. Wuebbles, University of Illinois Department of Atmospheric Sciences, “Atmospheric lifetimes and Ozone Depletion Potentials of trans-1-chloro-3,3,3-trifluoropropylene and trans-1,2-dichloroethylene in a three-dimensional model”, Nov. 2010