Document ID: OSHA-2008-0046-0070
Agency: osha
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-04-30T04:00Z

Site Visits Related to Diacetyl and Flavorings that Contain Diacetyl:

Food Production Facility C – Seasoned Snack Product Manufacturing

Table of Contents

  TOC \o "1-5" \h \z \u    HYPERLINK \l "_Toc215990225"  1	Introduction	
 PAGEREF _Toc215990225 \h  1  

  HYPERLINK \l "_Toc215990226"  1.1.	Project Overview	  PAGEREF
_Toc215990226 \h  1  

  HYPERLINK \l "_Toc215990227"  1.2.	Food Manufacturing Facility C -
Overview	  PAGEREF _Toc215990227 \h  2  

  HYPERLINK \l "_Toc215990228"  1.3.	Quantifying Diacetyl Usage	 
PAGEREF _Toc215990228 \h  2  

  HYPERLINK \l "_Toc215990229"  1.4.	Facility, Equipment, and Processes	
 PAGEREF _Toc215990229 \h  3  

  HYPERLINK \l "_Toc215990230"  1.4.1.	Seasoned Snack Food Production	 
PAGEREF _Toc215990230 \h  3  

  HYPERLINK \l "_Toc215990231"  1.4.2.	Packaging Room	  PAGEREF
_Toc215990231 \h  4  

  HYPERLINK \l "_Toc215990232"  1.4.3.	Q/A Laboratory	  PAGEREF
_Toc215990232 \h  4  

  HYPERLINK \l "_Toc215990233"  1.4.4.	Sanitation and Cleaning	  PAGEREF
_Toc215990233 \h  5  

  HYPERLINK \l "_Toc215990234"  2	Process Descriptions for Monitored
Employees	  PAGEREF _Toc215990234 \h  5  

  HYPERLINK \l "_Toc215990235"  2.1.	Production Worker	  PAGEREF
_Toc215990235 \h  5  

  HYPERLINK \l "_Toc215990236"  2.1.1.	Bag Dumping	  PAGEREF
_Toc215990236 \h  7  

  HYPERLINK \l "_Toc215990237"  3	Exposure Assessment	  PAGEREF
_Toc215990237 \h  7  

  HYPERLINK \l "_Toc215990238"  3.1.	Sampling and Analytical Methods	 
PAGEREF _Toc215990238 \h  7  

  HYPERLINK \l "_Toc215990239"  3.1.1.	Equipment	  PAGEREF _Toc215990239
\h  7  

  HYPERLINK \l "_Toc215990240"  3.1.2.	Limit of Quantification	  PAGEREF
_Toc215990240 \h  9  

  HYPERLINK \l "_Toc215990241"  3.1.3.	Blank Samples	  PAGEREF
_Toc215990241 \h  10  

  HYPERLINK \l "_Toc215990242"  3.2.	Air Monitoring Results	  PAGEREF
_Toc215990242 \h  10  

  HYPERLINK \l "_Toc215990243"  3.2.1.	Diacetyl and Acetoin	  PAGEREF
_Toc215990243 \h  10  

  HYPERLINK \l "_Toc215990244"  3.2.2.	Total and Respirable Aerosols	 
PAGEREF _Toc215990244 \h  10  

  HYPERLINK \l "_Toc215990245"  4	Examples of Controls in Place	 
PAGEREF _Toc215990245 \h  18  

  HYPERLINK \l "_Toc215990246"  4.1.	Overview	  PAGEREF _Toc215990246 \h
 18  

  HYPERLINK \l "_Toc215990247"  4.2.	Controls Associated with Individual
Jobs	  PAGEREF _Toc215990247 \h  18  

  HYPERLINK \l "_Toc215990248"  4.2.1.	Production Worker (Q/A–bag
dumping duty)	  PAGEREF _Toc215990248 \h  18  

  HYPERLINK \l "_Toc215990249"  5	Discussion	  PAGEREF _Toc215990249 \h 
19  

  HYPERLINK \l "_Toc215990250"  5.1.	Relationship between Results,
Sources of Exposure, and Controls in Use	  PAGEREF _Toc215990250 \h  19 

  HYPERLINK \l "_Toc215990251"  5.2.	Other Opportunities for Exposure
Control	  PAGEREF _Toc215990251 \h  19  

  HYPERLINK \l "_Toc215990252"  6	References	  PAGEREF _Toc215990252 \h 
20  

 Butter Flavor and Food Flavors Containing Diacetyl

Site visit report: 

Food Production Facility C – 

Seasoned Snack Product Manufacturing

Executive Summary

Diacetyl is a naturally occurring component of cheese and other cultured
dairy products, which are ingredients of seasonings applied to certain
snack foods. ERG evaluated worker exposure to diacetyl and acetoin
during surface application of a powdered seasoning slurry (seasoning
mixed with vegetable oil) via tumbler. This is the only use of
diacetyl-containing ingredients during production of this particular
snack food and the surface application occurs as the last step before
snacks are packaged in airtight bags. 

The employees who were monitored dumped 50-pound sacks of prepared
powdered seasoning into a hopper at hourly intervals to feed the
automated slurry production equipment. These same employees also
performed quality assurance tests on products and ingredients at various
points in the production process, spending approximately 70 percent of
the shift in the laboratory. 

Results of real-time air monitoring suggest only a modest contribution
to background aerosol levels from employees dumping bags of the two
seasoning formulations in use on this date and from the seasoning
application as a slurry in open-ended tumbler.

No diacetyl or acetoin was detected in air samples associated with snack
food production using these seasoning formulations. 

Introduction

Project Overview

Eastern Research Group, Inc. (ERG) conducted an industrial hygiene site
visit in June 2008 at Food Manufacturing Facility C, a seasoned snack
food production plant (hereafter referred to as Facility C). This is one
of a series of site visits conducted for the purpose of obtaining
information on: (1) the use of flavor products containing diacetyl and
commonly associated flavor ingredients (e.g., acetoin) in the
manufacture of food and beverage products; (2) the exposures of
employees at the facility to diacetyl and acetoin; and (3) the controls
in place to reduce exposure. In particular, the site visit was intended
to evaluate the exposures of workers who produce a fried savory seasoned
snack food, conduct quality assurance tasks, package the product, and
clean the work area.

In June 2008, three ERG industrial hygienists met with representatives
of Facility C to discuss the process of making the snack food product,
the materials used in this process, and the job categories with
potential for exposure to food flavorings that contain diacetyl. A
walk-through of the facility was conducted as part of the meeting. The
ERG team subsequently conducted short-term, partial-shift and full-shift
personal breathing-zone (PBZ) air monitoring and observed the work
practices of employees identified as having potential for exposure to
diacetyl. ERG also monitored real-time dust levels, performed area air
sampling for diacetyl and acetoin, and noted airflow patterns and
exposure controls in use at the facility. 

Food Manufacturing Facility C - Overview

Facility C manufactures millions of pounds of snack foods annually using
automated processes. Employees produce the foods in a variety of
flavors, including snacks coated with cheese flavor and non-cheese
flavor seasonings that contain ingredients that typically include
diacetyl as a natural component of the ingredient (e.g., cheese powder
or other flavored seasoning component). To make a seasoned product, a
seasoning agent is applied to the cooked snack as the last step before
the product is packaged. The product dough ingredients do not include
diacetyl-containing flavoring and production activities prior to the
seasoning process (e.g., dough mixing, frying, salting, cooling, and
most quality assurance [Q/A] tests) do not involve diacetyl-containing
flavorings. The final Q/A test, however, is performed after the
seasoning is added.

Quantifying Diacetyl Usage

The seasoning products used by Facility C during the site visit
contained naturally occurring diacetyl. The seasoning manufacturer
reports that the naturally occurring diacetyl concentration in a dairy
component of the mix is “less than 1 percent” of the prepared
seasoning as provided to Facility C. This quantity could potentially
vary from batch to batch and, based on the reported natural diacetyl
content of various non-butter dairy products, is likely to be 10 to 50
fold lower than this reported maximum of 1 percent. Facility C indicated
that naturally occurring diacetyl can contribute to the diacetyl content
and may be as high as 0.1 percent in some seasonings. Furthermore, a
company representative indicated that nearly half of the various
seasonings used by this company contain some naturally occurring
diacetyl. ERG was not permitted to collect a bulk sample of the
seasoning. 

The seasoning usage rate varies somewhat depending on the seasoning
flavor and snack food production rate. On the date of this site visit
(deemed “typical” by employees) the facility used approximately 100
to 200 pounds of seasoning per hour. Thus, the total amount of diacetyl
used during an 8-hour work shift could be between 0.16 pounds (about 2.5
ounces) and 16 pounds, always as a naturally occurring, integral
component of the pre-blended seasoning purchased by Facility C. The true
value probably falls at the lower end of this range. Information on the
acetoin content of the seasoning was not provided by the seasoning
supplier, which delivers the seasoning as a powder in 50-pound Kraft
paper sacks that are transported to the production area on pallets.

Facility, Equipment, and Processes

The plant was built as a dedicated food production facility in an
industrial park within the past 20 years. The facility is divided into
separate but adjacent production rooms comprising:

A single large multi-function production space, with a 20- to 30-foot
ceiling for product mixing, forming, frying and seasoning.

A large packaging area, with a drop ceiling at about 8 feet. 

Warehouse space.

A Q/A laboratory (including a typical laboratory hood and lab benches). 

Doors from the packaging and laboratory areas open into one corner of
the production space, near the seasoning application station. An
administrative zone (offices, reception, conference room) is physically
isolated from the production rooms. All areas are separated by latching
man doors or roll-up cargo doors and most doors were constantly kept
closed on the day of the site visit. 

Seasoned Snack Food Production

On the day of the site visit, the production space contained two
operating parallel production lines. During each of the three 8-hour
shifts per day, two employees typically control the automated production
process from a workstation in the Q/A laboratory. One worker is
responsible for dough mixing and for monitoring process equipment (no
direct seasoning handling), while the other conducts QA tests on all
phases of production and also dumps bags of seasoning powder into
hoppers. The two workers switch roles on alternate days, thus over the
course of a week both have the same potential exposure to seasoning
ingredients such as diacetyl. 

The freshly prepared snacks are conveyed into the tumblers, which apply
a specific flavor of seasoning powder uniformly across the product
surface. The large-diameter open-ended tumblers are elevated so that the
end discharging the product is above breathing zone-height.  Inside the
tumbler barrel, seasoning nozzles apply an oil/seasoning slurry to the
snack food as it proceeds through the tumbler.

The Production-Q/A worker uses unventilated bag dumping stations to
periodically refill hoppers with the dry seasoning used to make the
seasoning slurry. The bag dumping station consists of a hip-height
safety grate that sits flush over a hopper. Except when open for bag
dumping, a hinged cover folds over the grate. Seasoning is automatically
conveyed from the hopper through enclosed tubing leading to the tumbler.
Slurry production is an enclosed process. On the day of the site visit
two pairs of tumblers and associated hoppers were in use within 15 to 30
feet of the Q/A laboratory door. 

Packaging Room

Seasoned snack foods is transferred by conveyer to the packaging room.
Risers on the sides of the conveyer prevent product from falling from
the conveyer before it reaches a hopper that feeds the packaging
machine. 

The packaging room, used for several products, consists of a large area
containing numerous automated packaging machines of the form/fill/seal
type. From the point it is bagged, the product is completely sealed in
an airtight package with no possibility of seasoning release. 

Q/A Laboratory

As previously noted, the Q/A laboratory opens onto the snack food
seasoning area. The lab room contains a standard 4-foot wide vertical
sash laboratory hood. ERG measured an average air velocity of 152 feet
per minute at the hood face with the sash positioned at the pre-set sash
stop located at approximately 20 inches. ERG noted that the sash stop on
one side was not functioning, so the open sash hung at an angle.
Although the hood exhausted air when turned on, it is usually switched
off and the sash closed. On the day of the site visit, one employee
noted that the air seemed “stuffy” and wondered whether the normal
lab ventilation might have been temporarily shut down for repair as it
reportedly was in the adjacent packaging area.

Since day-to-day lab activities are performed on open benches, employees
indicated that the hood is used only rarely – for special projects.
The bench top activities for seasoned snacks include weighing snacks
foods, pulverizing them in a closed 1- or 2-liter canister on a blender
base (the size of a typical household blender), and performing tests on
ground snacks. The slight residual oil in this fried snack product
appears to have the effect of suppressing dust during the pulverizing
step and ERG noticed no visible airborne dust as the canister was
opened. Additional sensory tests are performed twice per shift and
involve an employee smelling and eating a few pieces of the snack food,
a process that takes a moment and involves markedly less than a single
consumer serving of this snack product.

Sanitation and Cleaning

Workers on the night shift typically clean equipment, using a water hose
to wash the tumblers in place. Conveyors are also cleaned in place,
either by hand or by automated water sprays at a specific point on the
conveyer line. During automatic cleaning, the operator activates the
automatic washing unit and runs the conveyer so the length of the belt
is cleaned as it passes through the washer. Wash water is collected in
drains below the conveyor. The cleaning operation is estimated to take
approximately 10 to 15 minutes. Equipment is also wet cleaned if
necessary when the seasoning flavor is changed, such as to avoid cross
contamination when switching from a dairy-based seasoning to a non-dairy
based seasoning. Wash water is reportedly usually cool; hot water is
seldom used except for sanitization purposes at the end of the cleaning
process.

Floors and surfaces are dry swept or wiped as necessary during all
shifts. In general there was very little spillage. Floors and surfaces
required only occasional minor sweeping.

Process Descriptions for Monitored Employees

Production Worker

ERG monitored two production workers consecutively performing the same
job during the shift.  Production Worker A (working in the
production-Q/A capacity this day), was monitored for approximately two
hours (116 minutes) at the beginning of the morning shift, which is
considered a particularly busy period. Production Worker A was observed
conducting quantitative quality control procedures on snacks from all
production phases (including pre-seasoned and seasoned) and dumping
50-lb bags of each of the two different seasoning powders (dairy-based
and non-dairy based) several times during the 2-hour period. One to two
bags of each seasoning were dumped approximately once every 20 minutes.
In all, over the 2 hours this worker spent a cumulative total of 22
minutes dumping 11 bags. Production Worker A, however, was called away
from the plant by a family emergency mid-morning.

The second worker, Production Worker B, spent the first several hours of
the workshift (not monitored) in the packaging department before being
transferred mid-day to replace Production Worker A. Production Worker B
was monitored for the second half of the shift. During this time, the
second worker performed the same activities described for Production
Worker A, except that Production Worker A had fully filled the seasoning
hopper before leaving, so less bag dumping was required during the
second half of the shift. Production Worker B spent a cumulative total
of approximately 15 minutes emptying seven bags over the course of the 3
hour sampling period. In the afternoon, one (or occasionally two) bags
of each seasoning were dumped once every hour or more.

The production workers stayed in their primary work area during the
monitored period, except during two 15-minute breaks and a 30-minute
lunch, and visits to the packaging area to obtain packaged samples for
QA testing (5 to 6 minutes) or to the plant administrative office (once
for 5 minutes). Table 1 summarizes job categories and major activities
associated with snack food seasonings used on this day.

Table 1.

Job Categories and Activities with Potential for Exposure to Flavors
That Contain Diacetyl  

Food Manufacturing Facility C – Chip Manufacture

June 2008

Job Title	Activities/Potential Sources of Exposure (percent of shift)

Snack Production Worker 

(A and B)	Rotates every other day between two primary jobs: 1) Q/A work
and seasoning bag dumping and 2) primarily overseeing dough mixing and
frying process equipment. 

During this typical Q/A–bag dumping day:

Q/A control functions in lab (65-70%). 

Work on production floor (20%), consisting of: collecting Q/A samples
from process equipment (15%); dumping bags of seasoning containing less
than one percent naturally-occurring diacetyl (5-10% of shift); cleaning
lab and production area (5%). 

Breaks (outdoors) and business in other parts of plant (10-15%).

Packaging Worker 

(area sample only)	Monitors function of multiple packaging machines from
a central console. Puts sealed bags of snacks in boxes. Changes rolls of
packaging film and adjusts equipment as necessary.  

Bag Dumping

The bag dumping operation consisted of the worker lifting a 50-lb bag of
seasoning powder onto a shelf on the bag dumping hopper so the bag is
between the worker and the hopper, using a knife to cut open the bag
along the long edge facing the hopper, and tilting the bag over the
hopper so the contents pour into the hopper grate. Throughout these
steps the opening in the bag is about 2 feet below, and points away,
from the worker’s face. Each worker was observed to have different bag
dumping styles but both workers who were monitored employed a restrained
style of dumping that generated minimal dust. ERG observed a small
amount of visible airborne dust, generally below the workers’
breathing zones. Tables 4 and 5 summarize the results of real-time
monitoring conducted while Production Worker B (the shorter of the two
workers) preformed this activity.

Another worker, observed on another shift during the initial walkthrough
portion of the site visit (not monitored), used a more energetic dumping
style. That third worker lifted the slit-open bag further above the
grate and shook the bag to free the last of the seasoning powder, which
formed a small visible dust cloud around the worker and the bag dumping
station. 

Each worker took approximately two minutes to prepare the station (lift
the cover, collect the bag from the pallet) and dump one 50-lb bag of
seasoning powder into the bag dumping hopper. The cover was lowered
immediately upon completion of the task. Empty bags were placed as they
were (not crushed, flattened or compacted) on a pallet.

During the day, a cumulative total of a few ounces of spilled seasoning
product was observed on the edges of the hopper and the surrounding
floor.

Exposure Assessment

Sampling and Analytical Methods

Equipment

Sampling and analytical methods are summarized in Table 2. ERG used SKC
AirCheck 2000 sampling pumps combined with an SKC constant pressure
controller (CPC, part number 224-26-CPC) and SKC adjustable-flow single
tube holders to draw either 0.10 or 0.05 liters per minute. The pumps
were checked for calibration levels immediately before sampling and
again at the end of the period using Drycal DC-Lite Primary Air Flow
Meters (5 ml/min to 5000 ml/min), model 412360, manufactured by Bios
International Corporation, Butler, New Jersey. 



Table 2.  Sampling and Analytical Methods

Analyte &

Sample Type	Sampling & Analytical Method	Media	Air 

Volume	Air Flow Rate	Sample Duration	Notes/Special Handling

Diacetyl/Acetoin

Short-term samples (15 to 30 minutes)

	OSHA Methods 1012 and 1013 [publication anticipated Fall 2008]	Silica
gel 

200/400 mg 

SKC 226-10-3 

(two tubes in series)	3 L	

100 ml/min

	15-30 minutes

	

Diacetyl/Acetoin

Partial-shift samples (30 to 180 minutes)	OSHA Methods 1012 and 1013
[publication anticipated Fall 2008]	Silica gel 

200/400 mg

SKC 226-183 

(two tubes in series)	9 L	50 ml/min

	3 hours

	Total and Respirable Dust

(real-time)	TSI DustTrak Aerosol Monitor 

(Model 8520)	N/A	N/A	1.7 L/min	Task duration	Instrument set to record
1-second readings. SKC nylon cyclone preceded sampling port for
respirable dust samples.

Air Velocity, Temperature, Humidity

(real-time)	TSI VelociCalc Air Velocity Meter 

(Model 9545-A thermal anemometer)	N/A	N/A	N/A	N/A	N/A

Notes:

L means liters.

ml/min means milliliters per minute.

SKC# indicates the brand and model number of sampling media.

N/A means “not applicable.”

ERG maintained all sampling media enclosed in appropriate size
semi-opaque plastic tube covers (SKC models 222-3-1 XD) attached to the
tube holders. Analysis was performed by the OSHA Salt Lake Technical
Center (SLTC) Laboratory, Sandy, Utah. 

All instruments and calibration equipment were factory calibrated within
the previous 12 months. 

Limit of Quantification

μg) per sample for diacetyl and 0.667 μg per sample for acetoin.

Results for samples in which no analyte was detected are reported as ND
(“none detected”). In calculating averages, ERG takes ND to be equal
to 0 parts per million (ppm). The laboratory did not provide a minimum
limit of detection (LOD), since the actual measured values were reported
down to the level at which no analyte was detected.

Blank Samples

ERG submitted media and field blanks for each batch of sampling media.
No measurable background levels of diacetyl and acetoin were reported
for blanks. 

Air Monitoring Results

Diacetyl and Acetoin

All samples were analyzed for diacetyl and acetoin; however, OSHA has
not published an exposure limit for either diacetyl or acetoin. For this
reason, all results are presented relative to each other, rather than
relative to a fixed standard. 

Table 3 provides details of all PBZ and area samples obtained at this
site. ERG collected 3 partial-shift PBZ samples for Production Workers A
and B. These samples were of 45 to 196 minutes duration and analyzed
using OSHA’s 2008 diacetyl/acetoin analytical method (publication
anticipated Fall 2008). One short-term exposure limit (STEL) sample was
also obtained for Production Worker A during the bag dumping task. To
give an indication of the airborne diacetyl in the packaging area, an
area sample was collected in that room (where Production Worker B spent
the first unsampled hours of the shift). No diacetyl or acetoin was
detected in any of these samples.

Total and Respirable Aerosols

Additional monitoring was conducted to evaluate the levels of total
aerosols and the smaller respirable aerosols (particles, droplets) in
the air near the seasoning application tumblers. Using real-time
analysis ERG collected 1- to 2-minute background measurements in the
tumbler area and laboratory, then obtained readings in the production
operator’s breathing zone during bag dumping activities.

Figure 1 suggests that the background total aerosol levels in the snack
seasoning area fluctuate even over periods as short as fractions of a
minute, but that, on average those levels are less than 1 milligram per
cubic meter (mg/m3). The associated Table 4 shows that aerosol levels in
the worker’s breathing zone during bag dumping are not appreciably
above background levels, although there may be a modest contribution
compared to times when background levels are low. 

The Facility C safety and health representative indicated that oil mist
aerosols are common in spaces where frying occurs and are likely present
in this space. Where mists are present, process enclosures and exhaust
ventilation help manage oil mist to levels that support sanitation
efforts and minimize fire hazards around heat sources. Frying occurs
before the seasoning step and does not involve any ingredients that
contain diacetyl.

Figure 2 and Table 5 suggest that aerosol particles greater than
respirable size account for only a modest portion of the total
concentration in the section of the production room containing the
tumbler. Furthermore, total and respirable aerosol concentrations
increased only slightly above background levels during bag dumping and
when measured near (within 1 foot of) the mouth of tumbler A. This
implies that the bag dumping and tumbling are not primary sources of the
background aerosols, although the data suggest that these could be
associated with modest increases in particulate levels in the immediate
area. 

Of the plant areas evaluated, Figure 3 and Table 6 clearly show that
aerosol levels in the laboratory are half or less of the concentrations
recorded for the production space. These findings confirm that
production workers do not release substantial amounts of dust during the
frequent Q/A tests. ERG believes that aerosol from the production area
likely enters the laboratory each time the door is opened. At the time
of the aerosol monitoring, the door was used heavily and opened
approximately four or five times in 10 minutes. Aerosol levels in other
(non-frying) production and administrative areas in the plant contained
less than 0.1 mg/m3 and less than 0.01 mg/m3 aerosol, respectively.

ERG estimated the maximum (worst case) diacetyl concentration that could
have occurred in the snack production work area if these particular
seasoning powders were the only source of the measured aerosol levels
(which they are not). Under those conditions, during bag dumping, a
maximum diacetyl concentration of 0.0023 ppm could have been associated
with the measured average aerosol level of 0.800 mg/m3 (from Table 4),
assuming a maximum of 1 percent diacetyl in the seasoning (the maximum
listed on the product material safety data sheet [MSDS]). In reality,
for reasons presented earlier in this report, the actual diacetyl
concentration is likely to have been substantially lower for the
employees that ERG evaluated. However, if an employee used different
work practices and created more airborne dust during bag dumping, that
employee could potentially experience a greater diacetyl exposure level
for the duration of the bag dumping activity.

Table 3.  Individual Air Monitoring Results for Food Manufacturing
Facility C – Snack Manufacturer

Sample

No.1	

Sample Type	

Sample

Duration

(minutes)	

Sample Volume

(liters)	Diacetyl Results	Acetoin results

Diacetyl 

Conc.2

(ppm)	

LOQ3

(ppm) 	

Result above LOQ?	Acetoin 

Conc. 2

(ppm) 	

LOQ4

(ppm) 	

Result above LOQ?

Production Worker A

C-1	TWA	116	6.04	  ND*	0.029	No	ND	0.031	No

C-4	STEL – Bag dumping	15	1.40	ND	0.124	No	ND	0.132	No

Production Worker B

C-6	TWA	196	11.50	ND	0.015	No	ND	0.041	No

C-5	TWA5	45	4.50	ND	0.038	No	ND	0.016	No

Area (Packaging Room)

C-2	General Area	231	11.34	ND	0.015	No	ND	0.016	No

Notes

1          Samples are listed by worker. Some workers were sampled more
than one time; as a result some of the sample numbers 	are out of
sequence. 

2	Sample concentrations are based on the period monitored (i.e., the
sample duration).  Samples were reported based on 	any amount of analyte
that was found; reporting limits were not considered.

0.609 micrograms (μg) per sample.

4	The reporting limit (limit of quantification) for acetoin is 0.667 μg
per sample.

5	Sample C-5 was obtained concurrently with sample C-6 and represents
approximately one task cycle.

*An ND result was reported by the laboratory when there was no
indication of the analyte in the sample. 

Temperature and humidity during collection of samples. C-1 and C-4:
T=74˚F, RH = 42-43%; C-5 and C-6: T=74˚F, RH= 42%; C-2: T=73˚F,
RH=47%.	Abbreviations

Conc. =	Concentration.

LOQ = Limit of quantification.

ND = Not detectable.  

TWA = Time-weighted average (for period sampled).

STEL = Short-term exposure limit (refers to a short-term sample obtained
over a 15- to 30-minute time frame).

FIGURE 1

Key to Monitoring Sessions:

Dumping two 50-pound bags of non-cheese flavor (up to 1 percent
naturally occurring diacetyl) into unventilated hopper that
automatically feeds flavor to tumbler A.

Dumping two 50-pound bags of cheese flavor (up to 1 percent naturally
occurring diacetyl) into unventilated hopper that automatically feeds
flavor to tumbler B.

Background aerosol levels in QA lab.

Background aerosol levels near tumbler A, 15 minutes after last bag
dumping activity.

Background aerosol levels near tumbler B, 15 minutes after last bag
dumping activity.

Table 4.  Summary of Total Aerosol Real-Time Sampling Results Associated
with Two Seasoning Application Tumblers* 

  	Total Aerosol  Concentration

Session (1)	Total Aerosol Concentration

 Session (2) 	Total Aerosol Concentration

Session (3)	Total Aerosol Concentration

Session (4)	Total Aerosol Concentration

Session (5)

Activity	Tumbler A, bag dumping (PBZ)	Tumbler B, bag dumping (PBZ)
Background – in lab 

(Area)	Background –Tumbler A 

(Area)	Background –Tumbler B 

(Area)

Average	0.553 mg/m3	0.800 mg/m3	0.269 mg/m3	0.490 mg/m3	0.816 mg/m3

Maximum	1.007 mg/m3	1.055 mg/m3	0.593 mg/m3	0.802 mg/m3	1.261 mg/m3

Minimum	0.478 mg/m3	0.530 mg/m3	0.253 mg/m3	0.452 mg/m3	0.458 mg/m3

Sample Duration	2:10

 (min:sec)

Duration of task	2:16 

 (min:sec)

Duration of task	2:27 

 (min:sec)

Representative sample	1:33

 (min:sec)

Representative sample	1:16

 (min:sec)

Representative sample

* Real-time air monitoring results obtained with a TSI DustTrak Aerosol
Monitor (Model 8520).

FIGURE 2

Key to Monitoring Sessions:

(1)  PBZ sample during dumping of two 50-pound bags of non-cheese flavor
(up to 1 percent naturally occurring diacetyl) into unventilated Tumbler
A feed hopper.

(4)  Area sample: background aerosol levels near Tumbler A, 15 minutes
after last bag dumping activity.

(6)	Area sample, collected with respirable dust cyclone: near Tumbler A.

(8)	Area sample, collected with respirable dust cyclone: near Tumbler A
- 1 foot from tumbler mouth.

(9)	PBZ sample, collected with respirable dust cyclone: during dumping
of two #50 bags of non-cheese flavor (up to 1 percent naturally
occurring diacetyl) into unventilated Tumbler A feed hopper.

Table 5.  Summary of Total and Respirable Real-Time Aerosol Results
Associated with Seasoning Application Tumbler A*

 

  	Total Aerosol  Concentration

Session (1)	Total Aerosol  Concentration

Session (4)	Respirable Aerosol  Concentration

Session (6)	Respirable Aerosol  Concentration

Session (8)	Respirable Aerosol  Concentration

Session (9)

Activity	Tumbler A, bag dumping (PBZ)	Background –Tumbler A (Area)
Background –Tumbler A

 (Area)	Near mouth of Tumbler A

(Area)	Tumbler A, bag dumping (PBZ)

Average	0.553 mg/m3	0.490 mg/m3	0.485 mg/m3	0.531 mg/m3	0.486 mg/m3

Maximum   	1.007 mg/m3	0.802 mg/m3	0.528 mg/m3	0.560 mg/m3	0.530 mg/m3

Minimum  	0.478 mg/m3	0.452 mg/m3	0.445 mg/m3	0.506 mg/m3	0.457 mg/m3

Sample Duration	2:10

(min:sec)

Duration of task	1:33

(min:sec)

Representative sample	1:44 

(min:sec)

Representative sample	1:03

(min:sec)

Representative sample	1:26

(min:sec)

Duration of task

* Real-time air monitoring results obtained with a TSI DustTrak Aerosol
Monitor (Model 8520).

PBZ: Personal breathing zone.

FIGURE 3

Key to Monitoring Sessions:

Time represented on this chart is sample run time.

(3)   Background aerosol levels in QA lab.

(4)   Background aerosol levels near tumbler A, 15 minutes after last
bag dumping activity.

(5)   Background aerosol levels near tumbler B, 15 minutes after last
bag dumping activity.

(11) Other food production area where no tumbling, seasoning, or frying
occurs.

Table 6.  Summary of Background Total Real-Time Aerosol Levels at
Facility C Various Locations*

 

  	Total Aerosol Concentration

Session (3)	Total Aerosol Concentration

Session (4)	Total Aerosol Concentration

Session (5)	Total Aerosol  Concentration

Session (11)	Total Aerosol  Concentration

Session (12)	Total Aerosol  Concentration

 (not graphed)

Location	Laboratory	Near Tumbler A 	Near Tumbler B 	Other production
area, no frying or seasoning	Conference room	Outdoors – parking lot

(dry, occasional breeze)

Average   	0.269 mg/m3	0.490 mg/m3	0.816 mg/m3	0.031 mg/m3	0.008 mg/m3
--

Maximum   	0.593 mg/m3	0.802 mg/m3	1.261 mg/m3	0.024 mg/m3	0.007 mg/m3
0.032 mg/m3 

Minimum   	0.253 mg/m3	0.452 mg/m3	0.458 mg/m3	0.053 mg/m3	0.010mg/m3
0.020 mg/m3

Sample Duration	2:27 

 (min:sec)	1:33

 (min:sec)	1:16

 (min:sec)	

1:01

(min:sec)

	0:19

(min:sec)	Multiple instantaneous samples

* Real-time air monitoring results obtained with a TSI DustTrak Aerosol
Monitor (Model 8520).

PBZ: Personal breathing zone.

Examples of Controls in Place

Overview

Most controls in place at Facility C are secondary benefits of workplace
conditions developed for other reasons (e.g., seasoning is applied as a
slurry to improve adhesion to the snack food, rather than for dust
control). ERG noted that the following existing controls (intentionally
or unintentionally) may help reduce the diacetyl and acetoin exposure of
production workers at the plant.

This facility relies primarily on dilution ventilation. Filtered fresh
and recirculated air are provided through a distribution system. Air is
exhausted near points where heat and oil mist (from the frying tanks)
are generated, with heat and oil mist capture the primary objectives.

The facility has an active housekeeping/sanitation program. Production
workers spend some portion of their shift cleaning – usually more than
once per day. ERG observed only minimal spillage of seasoning during the
site visit.

Controls Associated with Individual Jobs

Production Worker (Q/A–bag dumping duty)

Applying seasoning as an oil-based slurry prevents seasoning powder from
becoming airborne during the tumbling process. ERG monitored dust at the
open mouth of the tumbler and found only a minimal increase over
background aerosol levels.

The automated continuous slurry production equipment eliminates
potential employee exposure to the seasoning during mixing, although
production workers do come in contact with the powder while dumping bags
of seasoning into the hopper.

Employees use sealed canisters while grinding snacks for Q/A samples. 

The oil inherent in the product may act as a natural dust suppressant
during grinding, as there was no evidence of dust release when employees
opened canisters and poured out the contents.

Employee work assignment encourages the employees with the greatest
potential direct exposure to seasoning ingredients (those dumping
seasoning bags) to spend the most time in the laboratory, where aerosol
levels are lower. 

Packaging equipment is enclosed and of a design that helps limit dust
and vapor release to the atmosphere during packaging.

Discussion

Relationship between Results, Sources of Exposure, and Controls in Use

The low natural diacetyl content of the seasoning (nominally less than 1
percent and realistically probably considerably lower) minimizes the
potential for employee exposure. No diacetyl was detected in the
breathing zone of those employees who were monitored or in the packaging
area.  Additionally, by applying the seasoning as an oil-based slurry,
Facility C further reduces employee exposure to seasoning dust. The
careful work practices of the employees monitored during bag dumping
reduced the visible dust in their breathing zone compared to another
worker (observed but not monitored). Direct-reading instruments
confirmed that aerosol levels in the breathing zone were not greatly
increased above background levels during bag dumping.

Other Opportunities for Exposure Control 

Diacetyl was not detected in any air samples during the site visit to
Facility C. If additional exposure control is ever desired for the jobs
and situations observed at Facility C, the following options could offer
another level of exposure management:

An employee (not monitored) was observed during the initial walkthrough
using different bag dumping work practices than those of the employees
who were monitored the next day. The unmonitored employee was more
energetic in shaking the last of the seasoning powder from the bag,
lifted the bag higher, and was observed creating a larger cloud of dust
near the breathing zone. Some facilities find that employee feedback
techniques, such as video taping an individual’s work practices (then
showing the employee the video) and/or real-time aerosol monitoring can
help employees identify the behaviors that increase exposure. Workers
can learn to modify their work practices to generate less dust while
maintaining productivity.

The hopper into which bags were dumped at this facility included a flat
grate over the top of the hopper and a small flat flange around the
hopper mouth to limit spillage. Other designs of commercially available
bag hoppers include exhaust ventilation and an enclosure (booth) above
the grate to improve capture and reduce the spread of airborne dust.

ERG observed a trend for one of the two seasoning flavors (the cheese
flavor) to have a slightly greater natural potential to become airborne
than the other. While neither seasoning produced much flying dust during
careful handling, if it ever became necessary the seasoning manufacturer
might be able to modify the formulation to increase dust suppression
properties.

For flavors used in bulk quantities, bulk sacks and automatic discharge
systems eliminate both the need for employees to dump bags and the
repetitive manual handling of individual bags.

If flavoring component release ever needs to be controlled during
tumbling (e.g., vapors, dusty seasoning or product), it is possible to
enclose tumblers and add exhaust ventilation.

Employees stacked empty seasoning bags on a pallet for disposal.
Presumably those bags will need to be manually transferred to a
compactor, dumpster, or bin. A company representative indicated that
another method often used by this company is to place a collection bin
(rather than a pallet) in the bag dumping area. Employees transport the
bin to a bag compactor, which automatically lifts and empties the bin
without additional handling. In other industries, handling empty bags
has been show to be a source of employee exposure to powdered bag
contents.

If it is ever determined that greater dust control would be beneficial
during laboratory activities, most open-container processes might be
moved under the laboratory hood. 

Routine maintenance can help keep laboratory hoods and other ventilation
equipment used for exposure control in good working order. A sash stop
on the laboratory hood at Facility C was not functioning. Employees in
the packaging room indicated that the ventilation system (fresh air
supply) was not functioning on the day of the site visit (instead,
pedestal fans circulated air within the packaging area). 

References

Dairy Management. 2005. Buttermilk Powder Ingredients (fact sheet).
Dairy Management, Inc.

Vasavada, P.C. and C.H. White. 1979. Quality of Commercial Buttermilk.
Dairy Sci  62(5):802-806.

Wikipedia. 2008. Entry for Buttermilk. Accessed August 11 at   HYPERLINK
"http://en.wikipedia.org/wiki/Buttermilk" 
http://en.wikipedia.org/wiki/Buttermilk .

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iacetyl in the range of 0.5 to 4.5 ug/ml (or ppm), with an average
diacetyl content of 2 ppm (or 0.0002%). Desiccation to powder
concentrates the average component of buttermilk by greater than 10
fold. (Sources: Dairy Management, 2005; Vasavada & White, 1979;  
HYPERLINK "http://en.wikipedia.org/wiki/Buttermilk" 
http://en.wikipedia.org/wiki/Buttermilk .)

 One percent of 0.800 mg/m3 is 0.008 mg/m3.  The molecular weight (mw)
for diacetyl is 86.09.

ERG used the standard equation:  ppm = [mg/m3 x 24.45]/mw.  

 PAGE   2 

Site Visits Related to Diacetyl –Food Production Facility C