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MIOSHA Hazard
Alert
Spray-on Truck-bed Liner Operation
Proves Fatal
Fatality Summary
(Source: MIOSHA)
This year the MIOSHA program
investigated a fatality related to the spraying of truck-bed
liners. The spray-on truck-bed liner product contained a very
toxic chemical, methylene bisphenyl isocyanate (MDI). This alert
provides information on isocyanate use, the hazards associated
with isocyanates, steps to take to protect yourself, and contact
information for the MIOSHA Consultation Education & Training
(CET) Division, which provides free assistance to employers in
the State of Michigan.
The fatality occurred at
a small auto and truck accessory and detailing shop that purchased
the franchise rights to apply the spray-on truck-bed liner product.
The individual spraying the product had a previous acute exposure
to the MDI and had become sensitized. Due to inadequate training
on the hazards of isocyanate use, the individual was not aware
of this increased sensitivity. In addition, the facility did
not have a spray area with appropriate ventilation and had inadequate
respiratory protection for the employees. When a subsequent exposure
to the MDI occurred, it caused a fatal asthmatic reaction.
This unfortunate fatality
may have been prevented if any of the following would have been
in place:
+ Adequate training of employees on the hazards of isocyanate
exposure;
+ Sufficient ventilation inside a spray room or booth;
+ Respiratory protection that was properly selected, used, and
maintained;
+ Medical surveillance program for employees exposed to isocyanates.
What are isocyanates and
how are they used?
Isocyanates are a group of
highly reactive and toxic compounds used in the manufacture of
urethanes, foams, fibers, and coatings such as paints and varnishes.
Isocyanates are also found in the new and rapidly expanding business
of spray-on truck-bed liners. The application of the spray-on
truck-bed liner involves mixing a two-part product and spraying
the polymerizing liquid onto a cleaned and scuffed truck bed.
MIOSHA has established permissible
exposure limits for the isocyanate compounds methylene bisphenyl
isocyanate (MDI) and toluene-2,4-diisocyanate (TDI). Both MDI
and TDI have permissible exposure limits of 0.02 parts per million.
What are the hazards associated
with isocyanates?
Immediate or acute effects
of exposure to isocyanates include eye, nose, throat, and lung
irritation, and allergic sensitization. Acute effects may also
include stomach upset, vomiting, tightness in the chest, and
possibly fevers.
Repeated exposure to low
concentrations or a single exposure to high concentrations of
isocyanates may result in skin rashes, permanent breathing problems
including asthma, and hypersensitivity. Isocyanate exposure sensitizes
workers making them subject to severe asthma attacks if they
are exposed again, even at concentrations below the MIOSHA permissible
exposure limits. In extreme cases, death can occur from the severe
asthma attacks in sensitized individuals. If employees develop
any lung symptoms consistent with isocyanate exposures, they
should not be allowed future exposure to any amount of an isocyanate
until a physician has determined they are at no additional risk.
How do you protect yourself
and others from exposure to isocyanates?
Education and Training
An adequately trained workforce, including management and employees,
is the first step in reducing or eliminating the hazards associated
with the use of an isocyanate containing material. MIOSHA Hazard
Communication Standards require employers to provide employees
with information and training on any hazardous chemical in the
work area. The training should include the location of the material
safety data sheets (MSDSs), methods to detect the presence or
release of a hazardous chemical, the health hazards associated
with any hazardous chemical, and measures the employees can use
to protect themselves from these hazards.
Exposure Assessments
Employers must determine their employees potential exposure to
MDI or TDI. This will allow employers to evaluate engineering
controls such as ventilation in order to reduce exposures to
as low as reasonably achievable and aid in the selection of appropriate
respiratory protection. The permissible exposure limits are found
in the MIOSHA Part 301, Air Contaminants Standard.
Adequate Ventilation
Ventilation is probably the most important engineering control
when combating exposures to an isocyanate or other air contaminant.
The MIOSHA Part 528, Spray-finishing Operations Standard, requires
that all spray-finishing operations be performed inside of an
appropriate spray room or booth. In addition to providing ventilation,
a spray room or booth also provides a work area that is easily
restricted to only properly trained and equipped employees.
Respiratory Protection
Respiratory protection should not be the first line of defense
to protect employees from isocyanate exposure or for that matter
any air contaminant. Engineering controls such as ventilation
should be designed and utilized to reduce exposure to as low
as reasonably achievable before relying on respiratory protection.
The odor threshold, the level
at which an individual can smell an isocyanate, is higher than
the permissible exposure limits. In other words, if an employee
smells the sweet, fruity, pungent odor of an isocyanate, they
are probably overexposed. That is why the recommended respiratory
protection for employees exposed to an isocyanate is usually
a full-face supplied air respirator and not an air purifying
respirator (filter cartridge style). The problem with the air
purifying respirators is that they will reach a point at which
it becomes saturated and will no longer filter out the isocyanate.
When that filter breakthrough happens, an overexposure may occur,
causing an irreversible sensitization.
Personal Protective Equipment
The eyes and skin of employees working with isocyanate containing
products must be protected with the use of protective clothing
and equipment. Coveralls, gloves, footwear, and eye protection
are some of the things that should be considered when assessing
the potential for contact. The MIOSHA Part 433, Personal Protective
Equipment Standard requires employers to assess their workplace
to determine the need for such equipment.
Medical Surveillance Program
It is recommended that employers provide employees exposed to
isocyanate compounds with preplacement and annual physical examinations
with emphasis on the respiratory tract, including the existence
of respiratory conditions such as asthma and smoking history.
Individuals who have become sensitized should be assigned to
work areas where there is no expected isocyanate exposure.
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