Assessing risk from existing chemicals and certain uses of chemicals is the purpose of the Environmental Protection Agency’s (EPA) Toxic Substances Control Act (TSCA) Work Plan. As of September 2014, four chemical assessments were completed, two of which indicated the need for regulatory and/or risk reduction activities.

Conclusions from the TSCA Trichloroethylene Assessment

Each year, the United States uses 225 million pounds of Trichloroethylene (TCE), a volatile organic compound (VOC) and human carcinogen. TCE is used widely, primarily in industrial and commercial processes as a solvent, degreaser, and fixative. EPA’s Office of Pollution Prevention and Toxics (EPA/OPPT) focused the TCE assessment on characterizing human-health risks from inhalation and exposures to the chemical in scenarios that were expected to make frequent use of TCE in high concentrations and/or pose high potential for human exposure. 

While the EPA/OPPT recognizes that TCE can be absorbed through the skin, in light of the physical-chemical properties of TCE and the scenarios assessed, the EPA/OPPT chose inhalation as the main exposure pathway for the risk assessment. As a result, according to the EPA, the assessment may underestimate total exposures resulting from the uses of TCE. The assessment also does not include environmental impacts.

Ultimately, the EPA/OPPT assessment covered acute and chronic risks for thousands of workers in two types of businesses: 30,000 workers at small degreasing facilities using TCE as a degreaser and 300,000 workers at dry-cleaning facilities that use TCE as a solvent degreaser or spotting agent. Workers were both male and female (including pregnant women) and age 16 years and older. Risks were also assessed for “occupational bystanders,” such as workers in the vicinity of TCE operations but not actually performing the operations. The EPA/OPPT also included acute risks associated with consumer exposures in residential settings with risk estimates focused on pregnant women and their developing fetuses.

Since TCE was already known to be a human carcinogen, the results of the assessment reveal more about risk related to the level of exposure in degreasing and dry-cleaning operations. These include:

  • There are cancer risk concerns for users and bystanders occupationally exposed to TCE when using TCE‐containing degreasers and spot cleaners in small commercial shops and dry-cleaning facilities, respectively.
  • Many of the commercial vapor degreasing and spot cleaning exposure scenarios exceed the excess lifetime cancer risk probabilities of 1 chance in 10,000, 100,000, or 1 million (i.e., target cancer risks of 10‐4, 10‐5, and 10‐6, respectively) of an individual developing cancer.
  • Comparing the occupational exposures in degreasing vs. dry-cleaning operations, degreasing operations show the greatest cancer risk.

The assessment also revealed acute noncancer risks, including:

  • Developmental effects (i.e., cardiac defects) for most occupational and residential exposure scenarios (i.e., margins of exposure (MOE) were below the benchmark MOE of 10).
  • Comparing the occupational exposures in degreasing vs. dry-cleaning operations, degreasing operations show the greatest acute noncancer risk.

In addition, chronic noncancer risks were found to be:

  • Chronic noncancer risks for human health effects in both occupational scenarios (i.e., MOE below the MOE benchmark of 10), with an overall higher chronic risk for the degreaser exposure scenarios, including developmental effects (i.e., fetal cardiac defects), kidney effects, and immunotoxicity. In general, concern is irrespective of the type of exposure (typical vs. worst case) and the availability of room ventilation.
  • Reproductive effects and neurotoxicity for degreaser worker exposure scenarios and most of the degreaser bystander exposure scenarios. However, the risks concerns for these effects are reported for fewer spot cleaning worker/bystander scenarios and are generally attributed to exposure conditions without room ventilation.
  • Liver effects, although these are less prominent than those reported for other health effects and are found only in the degreaser worker/bystander exposure worst case scenarios and the spot cleaning worker/bystander worst case scenarios with no LEV.

Based on these findings the EPA recommends taking precautions to reduce TCE exposures, such as using the product outside or in an extremely well-ventilated area, and wearing protective equipment. Additional work is ongoing to define alternative chemicals and processes to replace TCE and reduce associated risks and subsequent health impacts using voluntary and regulatory actions.

Conclusions from the TSCA Dichloromethane Assessment

According to the EPA, the use of products containing Dichloromethane (DCM) for paint stripping poses some of the highest exposure risks compared to all uses of DCM. The chemical is a VOC and is also considered to have “likely carcinogenic properties.” In 2012, 261.5 million pounds of DCM were produced and imported into the United States, and the industry estimated demand in 2010 was 181 million pounds.

The EPA/OPPT estimates that more than 230,000 workers nationwide are directly exposed to DCM paint strippers, but this number does not include workers called “occupational bystanders” who are indirectly exposed. The populations targeted in the assessment are workers of both sexes, including pregnant females, and people 16 years of age and older, including both direct users and occupational bystanders.

Like the TCE assessment, the DCM assessment included only inhalation exposures, not skin exposures, and does not include environmental impacts. Although the assessment assumes a number of uncertainties inherent in available data and certain potential health concerns, the assessment provided a wealth of risk-related information.

Regarding cancer risks from chronic DCM exposure:

  • There are cancer risk concerns for workers exposed to DCM that are employed at various industries handling DCM-containing paint strippers,
  • Many of the occupational scenarios exceed at least one of the target lifetime cancer risks of 10-4, 10-5, and 10-6 (i.e., one chance in 10,000, 100,000, or 1 million, respectively), and
  • Workers handling DCM-based paint strippers with no respiratory protection for an extended period of time have the greatest cancer risk.

Non-cancer risks from chronic DCM exposures include:

  • Liver effects for most workers, including bystanders, using DCM-based paint strippers in relevant industries, with the exception of the art renovation and conservation industry, and
  • Non-cancer risks for most workers handling DCM-based paint strippers with or without respiratory protection for various exposure scenarios, with the greatest risk occurring in workers with long-term use of the product (i.e., 250 days/year for 40 years) without respiratory protection.

Non-cancer risks from acute DCM exposures include:

  • Neurological effects for most workers using DCM-based paint strippers that are apparent with or without the use of respiratory protection,
  • Concerns for incapacitating effects in workers handling DCM-containing paint strippers on an acute/short-term basis with no respiratory protection and for workers wearing different types of respirators, such as with assigned protection factor (APF) 10 or 25, while performing paint stripping in industries with high DCM exposure,
  • Neurological effects for consumers of DCM-based paint strippers at residential settings including bystanders staying in the residence when paint strippers are being applied,
  • Concerns for discomfort/non-disabling and incapacitating effects for consumers exposed to DCM while applying the product or staying in the residence after completion of the stripping task, including bystanders, when exposure conditions are at the highest in the rest of the house following completion of paint stripping, and
  • Unsafe exposure conditions for residential users, but not bystanders, of the product when it is applied in bathrooms. DCM concentrations may reach levels associated with non-disabling and incapacitating effects for the user applying the product. User relocation to the rest of the house after completing the paint stripping task may also produce non-disabling and incapacitating effects as DCM’s internal dose builds up in the body over time.

The assessment also revealed that noncancer risks are not found when workers reduce their exposure to DCM-based strippers by taking all three of the following actions:

  • Wearing respiratory protection (i.e., respirator with at least an assigned protection factor of 50),
  • Limiting exposure to central tendency exposure conditions (i.e., 125 days/year for 20 years), and
  • Working in facilities with low-end DCM air concentrations.

The EPA is currently considering a range of actions, both voluntary and regulatory, to mitigate risks from DCM. These include safer/greener chemicals and processes, promotion of best practices, and the phase-out of uses.

For more information or assistance with your Environmental and Health & Safety (EHS) regulatory Compliance needs, contact Ralph Carito at Total Environmental & Safety, LLC (Total) at 908-442-8599 or rcarito@TotalEnviron.com.