Chemical exposures

June 1, 2000
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How often do you think of doorknobs, tabletops and toilet seats as workplace health hazards? How about the paperwork on your desk or the magazine in your hands?

If your workers handle contaminants with chemical protective clothing or gloves, some of these supposedly benign objects could be sources of what experts call "secondary exposures."

That’s because, no matter how conscientious workers are about wearing protective clothing within regulated areas, anything they handle with a tainted glove outside that area may retain residual levels of surface contamination from toxic chemicals.

Consider this case as relayed (on terms of anonymity) by the corporate industrial hygienist for a national chemical company: Biological monitoring among employees in a 650-person chemical manufacturing facility showed exposure levels to a proprietary substance higher than they should have been. But inhalation levels were within OSHA limits. And workers wore PPE in contaminated areas.

To track down the hidden exposure source, the IH sent wipe samples from various surfaces around the facility to the company lab for analysis. Tests showed the contaminant was everywhere. Doorknobs, table-tops, toilet seats, and control panels in what were supposed to be clean zones all showed traces of the chemical.

Turns out, workers were soiling surfaces and themselves with their own dirty gloves. "They weren’t following procedures," says the IH. "They’d lay contaminated gloves down on a clean tabletop; open the bathroom door and lift the toilet seat before taking off their gloves; or jam their dirty gloves into a pants pocket and then shove their bare hand into the same pocket later while in the control room, contaminating themselves first, then the control panel." If only all compounds were like sulfuric acid, the IH half jokes, employees would quickly learn about secondary contamination sources.

Detect to protect

But most compounds aren’t like sulfuric acid, nor do they make their presence known as clearly as the glowing spots in the photograph on this page. Even most chemicals that can damage or permeate the skin -OSHA makes "skin notations" for 147 of the substances for which it regulates inhalation exposures- have no immediately noticeable health effects.

For a large chemical company where workers are biologically monitored and surface wipes can be analyzed routinely on-site, tracking down contaminated surfaces entails a little sleuth work. At a plant with fewer resources or where biological monitoring is not performed, these hidden hazards can go unnoticed or ignored.

Industrial Safety & Hygiene News’ July, 1996, cover story on dermal exposures and keeping surfaces clean triggered more than 20 reader inquiries for more information. Some said they had never thought about the risks of secondary contamination. "The article opened up a new can of worms for me," says one reader.

If your workplace is one where workers wear chemical protective clothing, secondary contamination is likely an issue. A good rule of thumb is, if a job requires chemical-resistant gloves, the potential for skin exposure via surface contamination exists, says chemist Tom Klingner.

There are several methods you can use to check exposure controls. Traditional wipe sampling with filter paper or adhesive tape can give a quantitative reading, for instance, telling you how many micrograms of a substance were detected in a square centimeter. But results can vary, depending on variables such as the wipe material or the surface texture. Measurements are limited to the particular square centimeter tested, and certain compounds evaporate too quickly to give accurate readings.

New surface testing methods include adapting environmental soil or water sampling kits to test work surfaces, PPE or skin contamination. For example, an object suspected of being contaminated, like a glove, can be washed and the wash water tested. Colorimetric tests -which work much like home pregnancy tests- are designed to react almost instantly to the presence of certain compounds like aromatic amines.

To be sure, human behavior isn’t always to blame when chemicals show up on strange surfaces. Mobile equipment can transfer contaminants from one area to another. So can ventilation systems. At another facility of the same national chemical producer mentioned above, an investigation into the cause of sneezing among workers in a newly constructed office area started out on the assumption that engineers were bringing contaminants in from the plant. But traces of the chemical found on desks and paperwork had been deposited by a ventilation system that sucked in fumes exhausted by a nearby production unit.

The unknowns

So, just how big a problem are desktops and doorknobs tainted with toxins? There’s no simple answer.

It’s not known just how much of any contaminant is safe on a surface. Industrial hygiene expert Shirley Ness lists 275 compounds considered skin permeants in her book "Surface and Dermal Monitoring for Toxic Exposures." But the only government surface contamination limits available are Department of Housing and Urban Development limits for lead, and EPA limits for polychlorinated bi-phenyls, according to Ness. Some OSHA standards- personal protective equipment, HAZWOPER, and standards specific to certain substances like lead, methylenedianiline, and asbestos- instruct employers to monitor surfaces or zones for contamination, but none explain how to determine what levels are safe.

"Exposure risk depends very much on the toxicity of the chemicals," says chemist Klingner. "If you’re dealing with carcinogens or chemicals that can cause an immune system response, any exposure is something to be concerned about." But traces of a less toxic chemical like isopropyl alcohol left on a control button or a sheet of paper may not make for a significant risk. The IH in the case described earlier in this story takes a zero-tolerance stand. "It all adds up. Even if the exposures are not significant, why do you want them?" he asks. "It’s like, you know you can get dog poop out of your carpet, but you still wouldn’t want to walk through it and track it into your house."

Earl Cook, senior industrial hygienist for OSHA’s health response team in Salt Lake City, says it’s up to employers to determine what levels of surface contamination are acceptable. "We expect employers to select a number. We review their criteria for selecting that number, and our people look to see if that level will protect workers efficiently," Cook says.

OSHA’s ambiguity is nothing new. A search for surface contamination information on the agency’s Internet site turns up a copy of a 1985 letter to OSHA from the safety manager of a hazardous waste cleanup business in Horsham, Pa., requesting "criteria that establishes surface permissible exposure limits’." OSHA’s response: There are none.

And as many employers already know, it’s uncommon for OSHA to take its own samples during an investigation. For instance, if inspecting a facility regulated by HAZWOPER, Cook says, "normal OSHA procedure is to evaluate the [written] program, observe it and talk to people."

Documenting liabilities?

That’s why, unless symptoms like sneezing or skin irritation persist, some employers, lawyers and industrial hygienists would rather avoid the entire issue. Testing surfaces could just be self-incriminating, they say.

For instance, a medical director in charge of worker health and safety for a group of Chicago-area hospitals came to Tom Klingner for help a few years ago. The doctor worried about the effectiveness of personal protective practices used in the hospital pharmacy. He was concerned that workers making up chemotherapeutic drugs could be contaminating their hands and the lab with the sort of toxins that make cancer patients’ hair fall out, Klingner says.

Klingner, whose company Colormetric Laboratories, Inc., in Des Plaines, Ill., makes surface contamination detection kits, used samples of the chemotherapeutics to develop a set of color indicator pads for testing pharmacy work surfaces. Within two minutes of being wiped on a countertop, drawer handle, telephone, or any other surface polluted with the same chemical, the pad would turn blue. If the surface was clean, the pad would stay white.

Colormetric’s "swypes," as they’re called, would provide the doctor with a simple, quick and cheap way to determine if he had a problem.

But in the end, the medical director was not allowed to test the pharmacy surfaces. Hospital administrators feared opening themselves up to liability by possibly documenting that exposures existed without knowing their significance. Instead, they updated the pharmacy’s safety policy, according to Klingner.

Keeping up with OSHA

Ignorance won’t be an acceptable defense for much longer, according to OSHA’s Earl Cook. For one thing, as technology advances and products like the "swype" are introduced to the market -at this point it’s only available for testing a few compounds- OSHA will expect employers to use them. "The more these things become available, the more we’re going to require them," says Cook. "We’re going to ask, "if the technology exists, how come you guys aren’t using it?’"

What’s more, the simplicity and cost effectiveness of colorimetric monitoring (a colorimetric pad costs about $2 as opposed to the $25 to $100 price-tag of sending a wipe sample for analysis) means OSHA could easily test during inspections. Tom Klingner is aware of one Colorado firm where compliance officers did just that: Inspectors used colorimetric indicators for aromatic amines to respond to an employee complaint about surface contamination. OSHA issued a citation based on technology the employer never knew existed, Klingner says. The company negotiated an 80 percent penalty reduction by agreeing to implement a urine monitoring program, Klingner says.

But Cook points out, the threat of OSHA using new technology shouldn’t be what spurs employers to implement their own surface monitoring programs. Under standards like HAZWOPER or lead, OSHA wouldn’t even need to do its own sampling to cite a company where a lack of procedures indicated lax contamination-control, he says.

Still, employers who seek OSHA’s guidance on how to control secondary surface exposures often turn away frustrated. Says Loren Jorgenson, safety manager for a rocket motor maker, "We have a number of chemicals for which we’re concerned about surface contamination. We’re looking for ways to increase our technical accuracy. But I don’t see any commonly accepted technique. Right now we clean until we feel it’s acceptable," he says.

At some point OSHA does intend to come through with a guidance: Earl Cook says his office has been at work on a surface contamination compliance directive for three years now.

Meantime, Klingner’s advice is, "If you find contamination, don’t worry about the level. Just get rid of it."

Sidebar: The human factor: keeping employees clean

The human factor is often to blame when contaminants are tracked into clean areas. Here are methods some safety managers use to reinforce proper procedures among workers who come into contact with chemicals:
  • "When we find contamination we make the workers go through the rigamarole of getting out the cleaning solution and cleaning everything off on their break time. When they realize they will have to walk around with a trashbag cleaning off doorknobs and toilet flusher handles the next time we find contamination, they’ll be more careful and more likely to speak up to a co-worker who doesn’t wash his hands," says a chemical company industrial hygienist.
  • The safety and health manager at an aerospace manufacturer in Arizona explains the notion of PH to help workers understand how damaging exposures can be. "If you sit down and show where milk, lemons, Draino and battery acid are on the PH scale,and then tell them what we’re dealing with is worse than battery acid, then they can relate to it," he says. "And we remind them to keep their hands clean by pointing out that hydroxide burns on their private parts aren’t fun."

    In the same facility’s plating shop, workers know not to rub up against or touch any equipment, railings, or doors, says the safety pro. "If they do, they hold their hand away from their body like it’s anathema until they get to the restroom to wash it."

  • Another safety manager threatens to withold pay from workers caught red-handed out of compliance with the PPE policy. "If someone’s been working this way 30 years and hasn’t had a problem, it’s tough convincing him to follow procedures. But we have found that people who aren’t concerned about their health are concerned about their paychecks," he says.


Sidebar: Sources for how to conduct surface monitoring

  • Surface and Dermal Monitoring for Toxic Exposures, by Shirley A. Ness, Van Nostrand Reinhold, 1994
  • Dermal Exposure Assessment Principles and Application, EPA publication EPA/600/8-91/011B
  • OSHA Technical Manual, Section I, Chapter 2, Sampling for Surface Contamination

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