Data-Base Proposal for Use in Predicting Mixer-Loader-Applicator

24 Data-Base Proposal for Use in Predicting Mixer-Loader-Applicator Exposure

Downloaded by EAST CAROLINA UNIV on January 3, 2018 | http://pubs.acs.org Publication Date: February 25, 1985 | doi: 10.1021/bk-1985-0273.ch024

DAVID R. HACKATHORN and DELMONT C. EBERHART Corporate Industrial Hygiene, Environmental Health Research Department, Mobay Chemical Corporation, Stilwell, KS 66085

Data obtained through a search of the published literature on mixer/loader and applicator exposure studies were evaluated and summarized by application technique and chemical class. As a result of this work, it was clear that the data in the open literature as they currently exist are insufficient to produce a data base capable of predicting exposure for risk assessment purposes. However, it was encouraging that where acceptable data of sufficient volume were available the correlations were quite good. This review of the literature revealed that incomplete reporting of data was a bigger factor in making data incomparable than was sampling technique. Differences in exposure evaluation technique were less important for comparing data than the way in which the exposures were reported. In response to this problem, a reporting format for field exposure data is proposed which would allow the development of a generic field exposure data base. If existing unpublished data were made available on a generic basis then the resulting data base could be used to develop exposure models for risk assessment. Worker exposure data i s a major component of r i s k assessment for the use of a g r i c u l t u r a l chemicals. It has become a routine part of the product review and r e g i s t r a t i o n process for new chemicals. Of special interest recently i s the exposure to workers who mix, load and apply pesticides i n the f i e l d . These work tasks are done by one, two or sometimes even three persons i n a work crew. There have been numerous studies conducted and reported i n the l i t e r a t u r e which characterize the exposure of this group under various a p p l i c a tion conditions. It i s this body of data which we have reviewed as a possible data base. 0097-6156/ 85/0273-0341 $06.00/ 0 © 1985 A m e r i c a n C h e m i c a l Society

Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


342

DERMAL EXPOSURE RELATED TO PESTICIDE USE

There are two purposes f o r the work presented here: f i r s t , to report on the s u i t a b i l i t y of the data available i n the l i t e r a t u r e for predicting mixer-loader/applicator exposure; and secondly, to propose a plan to accomplish development of a predictive model f o r t h i s exposure group. The idea of assembling a data base using e x i s t ing data i s not new but, i n f a c t , has been discussed f o r many years. The p r i n c i p l e has also been used on a limited basis by the Environmental Protection Agency and the C a l i f o r n i a Department of Food and Agriculture. However, no systematic review of the l i t e r a ture or d e f i n i t i o n of c r i t e r i a f o r a data base could be found. Therefore, an in-house study to investigate these needs was begun. Before we can t a l k about a data base, we should f i r s t i d e n t i f y what data we are talking about. For this purpose we have defined the worker exposure value as the amount of compound available f o r inhalation, dermal absorption or ingestion i n the work environment under consideration. Various measurement techniques including samp l i n g the a i r i n the breathing zone of the worker, recovering p e s t i cide contamination from the skin, or c o l l e c t i n g the pesticide impacting on a patch used to simulate skin contact have been used to estimate mixer/loader-applicator exposure. A l l of these methods attempt to measure the amount of chemical available f o r inhalation or dermal absorption i n the immediate environment of the worker. These exposure estimates are not s u f f i c i e n t of themselves to define the amount of chemical inhaled, absorbed or ingested by the worker. The dose received by the worker i s also dependent on intake and absorption factors such as breathing rate and dermal absorption rate. A l l of these factors must be considered f o r comparison of the estimated dose to the t o x i c i t y data i n a r i s k assessment. Although these factors are often chemical s p e c i f i c , the exposure value, as we have defined i t , i s not. We are therefore l i m i t i n g our proposal to include only worker exposure values which are free of chemical s p e c i f i c biases. Recently some emphasis has been placed on obtaining exposure data on each i n d i v i d u a l compound under consideration. These studies can be costly i n both time and money. In some cases they are not even a major factor i n the judgement of r i s k simply because the toxi c i t y and/or dermal absorption values are very low. In other cases the uncertainty of using exposure estimates from small sample groups compromises the r i s k assessment. Addressing these problems requires some form of data management. So we began by looking at the p o s s i b i l i t y of developing a generic exposure data base f o r at least the limited group, mixer-loader/applicators. This group was a good candidate because the exposure values as defined above are primarily dependent on the physical parameters involved i n the application process such as: Application Technique Application Rate Type of Crop Formulation Type Class of Compound Climatic Conditions Protective Equipment Work Practices


24.

HACKATHORN AND EBERHART

Data-Base

Proposal

for

Predicting

Exposure

343


In f a c t , i n order f o r the generic data base to be a viable approach, the following assumptions must be accepted. 1.

For most pesticides the d i s t r i b u t i o n of compound i n the work environment i s defined by the physical application parameters rather than the chemical properties.

2.

The major factor a f f e c t i n g exposure during application i s the physical d i s t r i b u t i o n of the compound i n the work environment.

3.

The major factors affecting exposure during mixing and loading are the formulation type, packaging type and mixing equipment.

While these assumptions appear to be v a l i d from our knowledge of exposure data, the actual proof can only be accomplished by comp i l a t i o n and review of a data base which i d e n t i f i e s these parameters for each study. Our f i r s t task was to conduct a thorough search of the published l i t e r a t u r e f o r mixer-loader/applicator studies. Each study was then reviewed c r i t i c a l l y for content and documentation of exposure parameters. Those studies found to be acceptable were catalogued f o r use i n the data base, and those studies found to be inadequate were l i s t e d with the reasons for r e j e c t i o n . A short form summarizing the data was then completed for each accepted study, and the data was segregated according to application technique, rate and compound c l a s s . Data summaries were then prepared for these groups. Further segregation of data was not possible due to the small number of acceptable studies and inconsistent reporting f o r mats which l i m i t the comparability of data between studies. Of the 82 mixer-loader/applicator studies found i n the l i t e r a ture, only 41 were determined to be acceptable. Some studies reported on more than one application technique and some application techniques were studied with several compound classes at more than one application rate. There were 12 exposure groups compared by application technique, application rate and compound class (See Table I ) . Some groups, such as a i r b l a s t spraying, contain more data than others. Tables I I , I I I , IV and V are examples of the type of summaries that can be prepared from data i n the l i t e r a t u r e . The major advantage to grouping the data and combining studies i s i n the vastly increased number of samples used to characterize the exposure range. In the case of a i r b l a s t spraying (Tables I I , III and IV) i n s u f f i c i e n t d e t a i l was available on i n d i v i d u a l samples to establish a group mean. Therefore, the range of means was used as a conservative representation of the data. Even so, this approach produces a more dependable estimate of exposure d i s t r i b u tion because of the large number of samples and exposure situations than can be obtained from a single study no matter how well the study i s done. The value of the data base model would be further improved i f the data were reported uniformly and i n s u f f i c i e n t d e t a i l that a group mean could be calculated from a l l the data points. The a e r i a l application data i n Table V shows a mean calculated from a l l the data points. The geometric mean and standard deviation are used


Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985. Compound Class

Organophosphates Organophosphates Chlorinated Insecticides Chlorinated Hydrocarbon Insecticides Fungicides

Organophosphates Herbicides

Organophosphates Chlorinated Hydrocarbon Insecticides

Organophosphates

Organophosphates Phenoxy Herbicides

Application Type

A i r b l a s t Spraying

Ground-Rig Boom

Power Hand Gun

Backpack Sprayer

A e r i a l Application

0.6-1.5 l b Ai/acre 2 l b Ai/acre

0.1-0.4% Spray

0.25-.67 l b AI/100 g a l 0.13-.42 lb AI/100 g a l

18 9

16

36 29

28 26

30

2 lb Ai/acre 0.5-3 l b Ai/acre 1-1.3 l b Ai/acre

131 90 85 40

lb lb lb lb

No. of Dermal Samples

AI/acre Ai/acre Ai/acre Ai/acre

0.5-3 3-4 1-3 4-8

Rate

Table I. Applicator Exposure Subgroups



0.02(-)

-

0.02-0.26 79

25

10

1.1-69.7

0.7-69.7

-

1.3-38

0.7-5.8

1.5-4.9

12.5(118.9)

2.4-27.9

27.9(-)

19.4(-)

18(-)

2.4(-)

2.5(-)

131

30

63

4

10

4

20

(4)

(4)

(D

(2)

(2)

(I)

Ref. Number

i n Orchards

Dermal Exposure (mg/hr)^ Range Mean # Samples

Respiratory exposure determined from respirator pads Dermal exposure calculated according to Durham and Wolfe (1962) (_5) Arithmetic mean and standard deviation

0.01-1.60

0.06(-)

12

0.03(-)

0.01-0.07

-

8

0.03(-)

0.01-0.05

4

0.08(-)

0.03-0.13

20

0.26(±.34)

0.07-1.60

Airborne Exposure (mg/hr) Range Mean # Samples

a

Table I I . Applicator Exposure During A i r b l a s t Spraying of Organophosphates Application Rate: 0.5-3 l b Ai/acre



0.05(-)

0.02(-)

0.07(-)

0.01-0.05

0.01-0.17

0.01-0.07

76

34

5

15

8

12

2

0.4-150.6

-

2.0-149.9

0.6-95.3

0.4-150.6

1.3-6.1

6.3-31.1

2.5-36.4

7.7(-)

36.4(-)

24.7(-)

30.5(-)

2.5(-)

15.5(-)

85

35

12

17

10

7

4

b

Dermal Exposure (mg/hr) Range Mean // Samples

(6)

(6)

(D

(3)

(3)

Ref. Number

Respiratory exposure determined from respirator pads (except #7 i n which personal ^ a i r samplers were used) Dermal exposure calculated according to Durham and Wolfe (1962) (5) Arithmetic mean and standard deviation

0.001-0.17

0.01(1.002)

O.Ol(-)

0.001-0.02

0.03-0.07

-

O.Ol(-)

0.02-0.04

Airborne Exposure (mg/hr) Range Mean # Samples

a

Table I I I . Applicator Exposure During A i r b l a s t Spraying of Chlorinated Hydrocarbon Insecticides i n Orchards Application Rate: 1-3 lb Ai/acre


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Data-Base Proposal for Use in Predicting Mixer-Loader-Applicator

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