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Chemicals by Land, by Sea, and in our Bodies?

September 22, 2022

 

It may come as a surprise to many of us, but several chemicals of industrial use are also made on a routine basis inside our bodies, of course in a much smaller amount. For example, ethylene oxide is used as a disinfectant to kill bacteria and virus on surfaces of hospitals. It has the added feature of being a dry gas, so it can be used to sterilize certain medical equipment, such as blood transfusion tubes, that are otherwise difficult to keep free of pathogens (I have written about this chemical before as shown here). Another chemical of huge industrial use is formaldehyde. Yes…that same chemical that was used to preserve the frog specimens that many of us studied in high school/college biology classes. Turns out that formaldehyde is extremely useful in making a number of other important chemicals, and yes our bodies make a small amount of it every day in our normal metabolism.

Aren’t these chemicals toxic? Of course they are! All chemicals are toxic AT SOME LEVEL. Ethylene oxide and formaldehyde cause tumors at high concentrations in experimental animals, and there is some evidence that they cause tumors in humans. However, levels causing these tumors are well above those that are bodies make daily, and industries making or using these chemicals protect their workers by establishing thresholds for safety, and include protective equipment.

Can the public be exposed to levels of ethylene oxide or formaldehyde that might cause us harm? Generally no. The levels of either of these chemicals in the environment more or less matches levels found in each of our bodies, so getting exposure to levels that can cause us harm is very unlikely. However, the U.S. Environmental Protection Agency has recently reaffirmed a previously established safe level of ethylene oxide and proposed a safe level of formaldehyde that are WELL BELOW what our bodies make every day. These levels are overly safe, and as a result call into question the process by which our EPA developed these estimates. For example, the overall impression of EPA’s current draft is that formaldehyde is toxic at levels below what is often found indoors or in outdoor air. Perhaps not surprisingly, many scientists disagree with EPA.

In fact, it is difficult for many of us to understand how EPA can propose safe levels for chemicals that are lower than levels that occur naturally or are produced in our bodies every day. It certainly is not because they do not have the good scientists. Dr. Rory Conolly, one of several of EPA’s former scientists who won the Lehman award from the Society of Toxicology (an award sometimes referred to as the Nobel prize for risk assessment), has published extensively on formaldehyde and is heavily cited in EPA’s text. However, Dr. Conolly disagrees with the current EPA position. EPA should listen.

EPA’s safety level for formaldehyde is still a draft. So what might EPA do to improve it?

First, EPA should focus on formaldehyde’s first toxic effect, which is tissue irritation. Estimating a safety level for other effects does not make sense, since all of these other effects are higher, and by definition the safety level based on irritation will protect against them. Second, EPA should follow its own guidelines for assessment of tumors and develop a safety level based on the way in which formaldehyde causes these tumors at high levels. Dr. Conolly suggests an approach that might work very well. Finally, EPA might consider new information from a recent scientific workshop that showed formaldehyde cannot penetrate the cell at low concentrations. This finding supports the threshold approach adopted by the European Union t al. (2020). 

It is certainly confusing that EPA proposes safe levels of these chemical that are below what our bodies makes every day. This makes it harder to trust other EPA assessments, many of which are very good.

WEEL OEL

Occupational Exposure Limits (OELs) are designed to safeguard the health of healthy workers during their careers. These limits are based on the assumption of repeated daily exposure throughout a working lifetime, typically averaged over an 8-hour workday. Their purpose is to prevent both immediate (acute) and long-term (chronic) health issues arising from workplace exposures. It’s important to note that OELs are not intended for the general public, which includes vulnerable groups like infants, the elderly, and those with pre-existing health conditions.

Workplace Environmental Exposure Levels (WEELs) are health-based guidelines for chemical hazards in the workplace. These values represent air concentrations believed to protect the majority of workers from negative health effects resulting from occupational chemical exposure.

The WEEL Process
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The development of new or revision of existing WEELs is typically assigned to voluntarily designated subcommittees. A subcommittee usually comprises 3 – 4 members from the WEEL Committee. New WEELs are developed using the OARS-WEEL administrative standard operating procedure (SOP), while existing WEELs are usually revised every 10 years, unless the availability of significant new data which may impact the existing WEEL value compels the committee to make a revision sooner. The OARS-WEEL SOP contains procedures and guidelines governing conflicts of interest, draft document preparation, literature searches, draft document review, balloting process, post-ballot WEEL documentation quality assurance scientific review, and publication.

Once a subcommittee has prepared a draft WEEL document, a review of the draft is scheduled for the next available Committee meeting. The WEEL Committee members are expected to have reviewed all such drafts prior to the meeting. If no major changes are necessary to a draft, the attending Committee membership may, by a simple majority, approve the WEEL for balloting. Alternatively, the Committee may direct the subcommittee to revise the WEEL and present it for further discussion at a future meeting. If a ballot is not approved by a two-thirds majority of non-abstaining Committee members, it is discussed at the next Committee meeting to determine the appropriate course of action. Once the WEEL is approved by a two-thirds majority of non-abstaining Committee members, copies of ballot comments are forwarded to the designated subcommittee and all substantive comments must be addressed in the final draft. If resolution of a substantive comment results in a change to the WEEL value or a change in the basis for the value, the draft must be re-balloted.

Once all comments have been addressed on a successfully balloted draft, document formatting and editorial review are performed by TERA, before the draft WEEL document is made available for public comment (usually for a period of 30 days but may be extended if the need arises). After the public comment period has elapsed, comments are addressed by the subcommittee responsible for that specific draft, after which the WEEL documentation is submitted to Toxicology and Industrial Health (TIH), a peer-reviewed medical journal that covers research in the fields of occupational health and toxicology, for publication. A thorough review of the galley proof by the scientific content quality coordinator at TERA, and proofreaders and editors at TIH is the penultimate step before eventual publication of the WEEL documentation.

The WEEL Committee

The OARS-WEEL Committee is composed of volunteer experts specializing in the scientific determination of occupational exposure levels. This committee actively seeks a balanced representation of professionals from toxicology and industrial hygiene, drawing upon a diverse range of experience from industry, government, academia, and consulting. Importantly, each member contributes to the Committee based on their individual expertise and not as an official representative of their respective employer, organization, or agency.