Tuesday, July 30, 2013

Industry News: EPA Seeks comments about ETO Inhalation Carcinogenicity

The EPA recently published a request for public comments in the Federal Register "Notice of a Public Comment Period on the Draft IRIS Carcinogenicity Assessment for Ethylene Oxide". The comment period closes on 8/23/2013. The National Center for Environmental Assessment (NCEA), part of the EPA's Office of Research and Development has drafted a report titled "Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide" available on the ISIS website. The first draft of this report was released in September 2006, and was revised following public comments, the second issue has now made its debut. The report summarizes the available evidence of carcinogenicity of EtO in humans and estimated the risk of developing cancer to someone as a result of exposure to EtO.

The two main conclusions of the report are that:
  • The weight of evidence from epidemiological studies and supporting information is sufficient to conclude that ethylene oxide is carcinogenic to humans.
  • Total cancer risk based on human data―lymphoid cancer incidence and breast cancer incidence in females is 1.80 × 10-3.
The report explained that "The derivation of unit risk estimates, defined as the lifetime risk of cancer from chronic inhalation of EtO per unit of air concentration, for lymphohematopoietic cancer mortality and incidence and for breast cancer mortality and incidence in females, based on results of the recent analyses of the NIOSH cohort, is presented in the following subsections."

In other words, a woman exposed to 1 ppm EtO for her lifetime has a 0.18% chance of contracting either breast or lymphoid cancer due to this exposure, i.e. on top of the risk of developing these or other cancers due to others reasons.

This report is 174 pages long and so the brief summary here does not do it justice and therefore anyone interested is advised to download and read the report and perhaps offer comments to the EPA..

Tuesday, July 9, 2013

Chemical Management in HealthCare

A recent paper by Byrns, Nelson and Bradbury (The Importance of Good Chemical Management in Health Care, J. Occup. & Environ. Hyg. (2013), 10(7), D86-93) discussed their results from auditing two large hospitals for chemical management. Hospitals use a large number of chemicals from disinfectants by house keeping, sterilants by sterile processing and pharmaceuticals, especially antineoplastic drugs, by pharmacy and medical staff; and many of these chemicals pose significant risks to anyone exposed to them. The use of chemicals in the workplace, whether a hospital or in general industry is regulated by OSHA and the management of chemicals in the workplace is governed by OSHA's Hazard Communication Standard.

The goal of the HazCom standard is to inform workers of the risks of the chemicals that they use. The standard's philosophy is that if workers know and understand the risks of the chemicals they are using then they will be more careful and there will be fewer chemical related injuries. The HazCom standard includes requirements for labeling chemicals (recently revised under the Global Harmonization System), safety data sheets (SDSs), formerly MSDSs, and employee training as well as maintaining an inventory of all chemicals on-site.

Byrns et al found very poor adherence to the Hazcom standard. In the first hospital they audited they found that the facilities engineering department had 248 chemicals on-site, but there were SDSs for less than half of the chemicals (115) and only 114 of them were in the chemical inventory. On the positive side the authors found most of the workers knew which were the most hazardous chemicals, but the use of personal protective equipment was inadequate. Similar results were found with housekeeping.

Hospital 2 did not do any better in their audit. The facilities Engineering had poor control of their chemical inventory (46% of chemicals listed), the nursing and radiology had very poor control, but the sterile processing department was much better with over 90% of their chemicals listed.

On the positive side, there were no reports of serious acute exposures and the percentages of employees who said they had received training on how to use the chemicals in their workplace safely was 100% in Sterile Processing and Chemotherapy Nursing though it fell to 44% for Engineering and 0% for pharmacy.
The overall low focus on worker safety in healthcare is well documented (and well cited in the article), and the above results support this conclusion.

For comparison, ChemDAQ's informal survey at the recent IACHSMM show, which was discussed in a recent blog found that almost half of respondents (predominantly sterile processing personnel) said that they had never received training on the Hazcom standard, which indicates that the two hospitals taking part in the Byrns et al study may be been among the more progressive with regard to chemical safety.

Tuesday, July 2, 2013

Protective Action Criteria - Emergency Exposure Limits

Most of us are aware that there are exposure limits for chemical exposures in the workplace, so called occupational exposure limits (OELs). In the US, the legal exposure limits are in the form of OSHA Permissible exposure limits (PELs) available at 29 CFGR1910.1000 Tbl Z-1. There are several other OELs that are based on scientific data including the NIOSH recommended exposure limits (RELs), the ACGIH threshold limit values (TLVs) and the AIHA’s workplace environmental exposure levels (WEELs).

In addition to OELs, there are also emergency exposure levels.  The main difference between OELs and PAC levels are that OELs are intended for the workplace where one may be safely exposed to this concentration or concentration over time, for eight hours, 5 days a week for a full work life without adverse effects. Emergency exposure levels on the other hand are intended for emergency responders as a tool to assess the risk to people who have had a one time exposure to a chemical.

There are the three main emergency exposure levels in common usage. The EPA has promulgated acute exposure guidelines (AEGLs) and the AIHA has issued Emergency Response planning guidelines (ERPLs). The AEGLs and ERPLs are subdivided based on the impact of an exposure.The AEGL levels are defined as follows:

  • AEGL-1 is the airborne concentration, expressed as parts per million or milligrams per cubic meter (ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.
  • AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.
  • AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death.
 The ERPLs are similarly divided, with similar definitions:
  • ·ERPG-1 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hr without experiencing other than mild transient adverse health effects or perceiving a clearly defined, objectionable odor.

  • ERPG-2 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hr without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.
  • ERPG-3 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects.
The main difference between the AEGLs and the ERPGs is the ERPGs are based on a one hour exposure, whereas the AEGLs are calculated for exposures from 10 minutes to 8 hours.

The AEGL and ERPG values can be compared with the NIOSH immediately dangerous to life and health levels (IDLH).

Some values for representative compounds are shown in the table below:

Ethylene oxide
45 ppm
50 ppm
800 ppm
1 ppm 8 Hr TWA
1.7 ppm
5.0 ppm
1 ppm
10 ppm
20 ppm
0.3 ppm ceiling
0.2 ppm
1 ppm
0.05 ppm ceiling
Hydrogen Peroxide
10 ppm
50 ppm
75 ppm
1 ppm 8 Hr TWA
Peracetic Acid
0.17 ppm
0.51 ppm
Notes: AEGLs based on 60 minute exposure.
        *The ACGIH has proposed a 15 minute STEL for peracetic acid of 0.4 ppm.

As may be expected, the AEGLs and ERPGs are significantly higher than the ACGIH TLVs, since the former apply to a one time exposure in an emergency situation and the latter to occupational exposure, 40 hours a week.

Both the AEGLs and the ERPGs are based on scientific studies; however for many chemicals systematic exposure studies have not been conducted. The last member of the PAC family are the DOE Office of Emergency Operations’ temporary emergency exposure limits (TEELs) developed by SCAPA.

The TEELs are estimates made based on OELs, chemicalproperties, chemical structures, health hazard warnings etc The goal behind the TEEL program is to estimate an emergency exposure level based on the information available. The development of a TEEL is not a rigorous as an AEGL or ERPG, but in an emergency situation it is much better to have TEEL guidance than nothing at all. The TEELs are subject to periodic update and TEEL compounds may also rise to the top of the pile and become and AEGL or ERPG.  The TEELs are also divided similarly to the AEGLs and ERPGs into TEEL-1, TEEL-2 and TEEL-3. 

Today there are over 3000 TEELs  compared with about 140 final AEGLs and about 145 ERPGs.

The Emergency Management Special Interest Group (sponsored by the Department of Energy)  combines these emergency exposure limits into Protection Action Criteria (PACs)  to give PAC-1, PAC-2 and PAC-3 as with the AEGLs and the ERPGs.  For any particular chemical, the PAC is based on the following hierarchy of values:

1) Use AEGLs (including final or interim values) if they are available.
2) If AEGLs are not available, use ERPGs.
3) If neither AEGLs or ERPGs are available, use TEELs.

The PAC values are designed for use by first responders and other people dealing with potential chemical exposures in an emergency. The PAC values are available from an on-line database and tabulated in pdf and Excel formats