Reliability and factorial validity maule chile

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International Journal of Environmental Health Research
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Reliability and factorial validity of a questionnaire
to assess organophosphate pesticide exposure to
agricultural workers in Maule, Chile
María Teresa Muñoz-Quezada, Boris Lucero, Asa Bradman, Brittney
Baumert, Verónica Iglesias, María Pía Muñoz & Carlos Concha
To cite this article: María Teresa Muñoz-Quezada, Boris Lucero, Asa Bradman, Brittney
Baumert, Verónica Iglesias, María Pía Muñoz & Carlos Concha (2018): Reliability and factorial
validity of a questionnaire to assess organophosphate pesticide exposure to agricultural
workers in Maule, Chile, International Journal of Environmental Health Research, DOI:
10.1080/09603123.2018.1508647
To link to this article: https://doi.org/10.1080/09603123.2018.1508647
© 2018 The Author(s). Published by Informa
UK Limited, trading as Taylor & Francis
Group
Published online: 19 Aug 2018.
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ARTICLE
Reliability and factorial validity of a questionnaire to assess
organophosphate pesticide exposure to agricultural workers in
Maule, Chile
María Teresa Muñoz-Quezada a,b
, Boris Luceroa,b
, Asa Bradmanc
, Brittney Baumertd
,
Verónica Iglesias e
, María Pía Muñoze
and Carlos Conchaa
a
Faculty of Health Sciences, Universidad Católica del Maule, Talca, Chile; b
The Neuropsychology and Cognitive
Neurosciences Research Center (CINPSI Neurocog), Universidad Católica del Maule, Talca, Chile; c
Center for
Environmental Research and Children’s Health, School of Public Health, University of California Berkeley, Berkeley,
USA; d
PhD in Environmental Health Sciences, Rollins School of Public Health, Emory University, Atlanta, USA;
e
School of Public Health, Faculty of Medicine, Universidad de Chile, Santiago, Chile
ABSTRACT
The aim was to evaluate the reliability and validity of a questionnaire to assess
organophosphate pesticide (OP) exposure in agricultural workers. We then
enrolled a random sample of 114 agricultural workers from the region of
Maule, Chile (mean age = 50 years [SD = 12]). An internal consistency analysis
(Cronbach’s alpha> 0.70) and a Varimax rotational factorial analysis were
applied. The instrument had a high reliability to predict likely occupational
pesticide exposures: Cronbach’s alpha = 0.95, the Kaiser–Meyer–Olkin (KMO)
measure was 0.90 and the Bartell sphericity test = p < 0.001. Four factors
explaining 68% of the variance were extracted. The factors identified were as
follows: (1) labor conditions during application of OPs; (2) use of personal
protective equipment; (3) workplace conditions related to OP exposure and
(4) home conditions related to OP exposure. The questionnaire has adequate
metric properties to characterize likely OP exposure of agricultural workers
and to explore associated working and home conditions.
ARTICLE HISTORY
Received 15 February 2018
Accepted 30 July 2018
KEYWORDS
Pesticide; exposure
assessment; questionnaire;
farmers; occupational
hazards
Introduction
Organophosphate pesticides (OPs) are the most widely used and sold insecticides (Suratman et al.
2015). They are predominately used to control pests in agricultural settings. Human exposure to
OPs can adversely affect human health (Liu et al. 2014; Lerro et al. 2015; Sánchez-Santed et al.
2016; Urlacher et al. 2016; Muñoz-Quezada et al. 2016a). Acute intoxication results in headache
and abdominal pain, nausea, vomiting, dizziness, dermatitis, skin lesions, sleep problems, saliva-
tion, blurry vision, leg cramps or muscular weakness (Azazh 2011; Jensen et al. 2011; Suratman
et al. 2015), extrapyramidal symptoms (Reji et al. 2016), kidney injury (Lee et al. 2015), among
others. Severe intoxication may result in death (Lee et al. 2007). Cognitive and motor difficulties
are the most commonly described neurotoxic conditions associated with chronic occupational
exposure to OPs (Starks et al. 2012; Meyer-Baron et al. 2015; Muñoz-Quezada et al. 2016a, 2016b;
Corral et al. 2017). Recent studies have also shown OP exposure is related to emotional dis-
turbances (Mackenzie Ross et al. 2010; Harrison and Mackenzie Ross 2016), asthma, allergies
(Hoppin et al. 2009), Parkinson’s disease, neuropathy (Povey et al. 2014) and cancer (Alavanja and
Bonner 2012) and poorer neurodevelopment in children (Bouchard et al. 2011; Rauh et al. 2012).
CONTACT María Teresa Muñoz-Quezada mtmunoz@ucm.cl Faculty of Health Sciences, Universidad Católica del Maule,
Avenida San Miguel, 3605 Talca, Chile
INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH
https://doi.org/10.1080/09603123.2018.1508647
© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://
creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the
original work is properly cited, and is not altered, transformed, or built upon in any way.

OP exposure is usually assessed through measurement of either acetylcholinesterase (AChE)
activity in blood or metabolites in urine (Wessels et al. 2003). When levels of blood AChE are low,
it is assumed that the individual is exposed to OPs, especially if comparisons to baseline,
prexposure AChE show declines. Measurements of erythrocyte cholinesterase are used to evaluate
chronic exposure and also cases of acute intoxication. The measurement of plasma AChE is only
useful to evaluate acute intoxications. Urinary biomarkers are so far the most sensitive to assess
OP exposure and involve measurement of dialkylphosphate metabolites or specific metabolites of
OPs such as chlorpyrifos, methamidophos, malathion, diazinon or dimethoate (CDC 2015).
The methods described above, while relatively sensitive and specific for measurement of OP
exposure, are costly, both to collect the samples and to conduct laboratory analysis. In Latin
America and developing countries, there are few laboratories and staff prepared for blood analysis.
For measurement of pesticide metabolites in urine, certified centers are mainly in the United
States of America (USA) or Europe (Muñoz-Quezada et al. 2016a). For follow-up or monitoring
studies, occupational exposure to OPs and health conditions are often evaluated through ques-
tionnaires or review of clinical symptoms (Engel et al. 2001; Samanic et al. 2005). Recent studies
have employed questionnaires to investigate pesticide exposure, use of personal protective equip-
ment (PPE) and health problems; however, few studies have examined reliability and validity of
these instruments (Samanic et al. 2005; Beseler and Stallones 2006; Lekei et al. 2014; Potts et al.
2014; Damalas and Abdollahzadeh 2016; Gesesew et al. 2016).
In Chile, epidemiological surveillance of workers exposed to pesticides is conducted based on a
protocol developed by the Ministry of Health (2017) that aims to prevent health problems. Based
on review of the potential for pesticide exposure by the Institute of Public Health of Chile (ISPCH
2004), a questionnaire was developed to specifically assess occupational and household exposure
to OPs in both applicators and nonapplicators working in agriculture and symptoms of intoxica-
tion. In the following study, we evaluate the reliability (internal consistency) and factorial validity
of a brief questionnaire to assess exposure to OPs, working conditions, and symptoms of
intoxication among agricultural workers that can be used to support research and investigations
aiming to prevent adverse health effects from pesticide exposure.
Methods
Study design
We enrolled a cross-sectional sample of 114 agricultural workers living in the region of Maule,
Chile.
Study groups
About one-third of the population, estimated at 305,077, in this region is rural, the highest proportion
in Chile, and 30% of the workers in the region work in agriculture (Government of Chile 2015).
According to the Chilean Agricultural and Livestock Service (SAG 2012), the region has the second
largest sales of pesticides in the country (Maule ~ 10million kg/L), with a 29% of insecticides used
nationally, of which 52% are OPs. In the Maule district, diazinon (~ 1 million kg/L) and chlorpyrifos
(~ 231,000 kg/L) are the most commonly used materials.
We identified agricultural workers for potential recruitment with help by the Institute of
Agricultural Development (INDAP), a government agency that supports small agricultural pro-
ducers. The sample was a subset of a larger study evaluating OP exposure and neuropsychological
and motor performance in rural populations (Muñoz-Quezada et al. 2016b). Agricultural workers
were randomly selected from INDAP records and contacted to schedule a meeting to obtain
informed consent and administer the questionnaire. Pregnant women, workers with mental
disabilities or severe psychiatric disorders or any disabling diseases were excluded. This study
2 M. T. MUÑOZ-QUEZADA ET AL.

was approved by the ethics committee on human research of the Universidad Católica del Maule.
Written informed consent was obtained from all individual participants included in the study.
Questionnaire
The questionnaire was based on pesticide exposure instruments developed by the Institute of
Public Health of Chile (ISPCH 2004), with additional questions added to assess exposure
characteristics, occupational conditions and the health status of agricultural workers. The ques-
tionnaire was revised based on review by six experts in pesticide exposure and psychometrics.
They reviewed the questions and agreed which were pertinent to pesticide occupational exposure
issues. The agreement achieved in the final version was 100%. The questionnaire was then pilot
tested in 17 exposed and 17 nonexposed workers to assess only the applicability of language and
response categories.
The first section of the questionnaire (26 questions) asked about sociodemographic data and
general health conditions considered to be hazardous for an agricultural worker exposed to
pesticides and to confirm that the worker applies OPs (see Appendix A1). The remaining
questions obtained information on demographic and occupational characteristics, job title (appli-
cator/nonapplicator), pesticide exposure risk factors, use of OP or other pesticides, housing
conditions and home pesticide use. Additional information was obtained about symptoms of
potential OP poisoning. The questionnaires were administered written in Spanish; interviewers
provided additional help to those workers with reading and writing difficulties. The answers to the
questionnaire were tallied, with a maximum score of 65 points, and with higher scores represent-
ing greater risk of pesticide exposure and health effects. Questions answered as ‘not applicable’
were coded as zero (0).
Data analysis
First, the sociodemographic characteristics of the sample were briefly analyzed.
To determine the validity of the instrument, we performed a factorial analysis with extraction
method of principal component analysis (PCA) with the Varimax rotation method. We describe
the Kaiser–Meyer–Olkin (KMO) sample adequacy measure and the Bartlett sphericity test to
compare the magnitude of observed and partial correlation coefficients.
Subsequently, an internal consistency analysis (Cronbach’s alpha equal to or greater than 0.70)
was employed with the total scores of the test and with each factor, applying a corrected item-total
correlation analysis. Finally, we calculated the descriptive statistics of the total score of the
instrument and the factors obtained after the factorial analysis. A 95% confidence interval was
used. SPSS 22.0 software was used for data analysis.
Results
The average age among participants was 50 years old (SD = 12). Overall, participants had an
average of 21 (SD = 16) years working in job categories with potential pesticide exposure. Sixty-
seven percent were applicators (n = 76), who had been applying pesticide for an average of 10
(SD = 13) years. On average, participants had 8 years of school education (SD = 3), and 65%
(n = 74) were men. The average household monthly income = $344 (SD = 147) USD, similar to
the minimum wage of Chile of that time.
Table 1 shows the frequency and percentage of response for each of the questions. We note that
all the alternatives of the questionnaire contain at least one answer from the workers, and there
are no questions with a total score of zero points.
The sample adequacy measure of Kaiser–Meyer–Olkin (KMO) results = 0.90 and the Bartell
sphericity test = p < 0.001. The initial eigenvalues were six factors (cumulative variance = 75%).
INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 3

Table 1. Percentage of the pesticide exposure questionnaire OP.
Question (score) Frequency
Percentage
response
Are you currently working applying pesticides?
– No (0) 38 33
– Yes (1) 76 67
When was your last pesticide application?
– Not applicable (0) 38 33
– 2 years or more (1) 4 4
– Less than 2 years (2) 72 63
Do you work as a seasonal or permanent pesticide applicator?
– By season (1) 10 9
– Permanent (2) 66 58
Do you have a pesticide applicator license?
– Yes (1) 16 14
– No (2) 60 53
Do you eat, drink or smoke during the application?
– No (1) 13 11
– Yes or occasionally (2) 63 55
Do you change your clothes after the application?
– Yes (1) 21 18
– No or occasionally (2) 55 48
The place where pesticide is mixed is:
– Open (1) 67 59
– Closed (2) 9 8
Do you use manual pump backpack to apply OPs?
– No 45 40
– Yes 69 60
What type of OP do you recall applying?
– Only one OP (1) 66 58
– More than one OP (2) 10 9
Do you wear personal protective equipment when mixing?
– Yes (1) 48 42
– No (2) 28 25
Do you know the health risks you are exposed to when applying or mixing pesticides?
– Yes (1) 57 50
– No (2) 19 17
How many years have you applied pesticides?
– 10 years or less (1) 36 32
– More of 10 years (2) 40 35
How long does it take between the end of the application and taking a shower or bath?
– Less of 15 min (1) 43 38
– 15 min or more (2) 33 29
During or after pesticide application, do you wash your hands before smoking, eating or
drinking?
– Yes (1) 45 40
– No or occasionally (2) 31 27
If you change your clothes after work, where do you do it?
– Work (1) 52 46
– Home (2) 24 21
Are you trained on the health risks of pesticides?
– Yes (1) 38 33
(Continued)

Table 1. (Continued).
Percentage
response
– No (2) 38 33
Where do you wash the machinery?
– Does not wash, not applicable (0) 49 43
– In a dedicated place for washing (1) 9 8
– Yard, orchard, pasture or ﬁeld (2) 50 44
– Inside the house (3) 6 5
Besides applying OPs, do you mix and prepare them?
– No or not applicable (0) 50 44
– Yes (1) 64 56
Where do you store the pesticides?
– Warehouse at home or work (1) 52 46
– In the house’s yard (2) 7 6
– Inside the house (3) 17 15
Do you use a motorized pump backpack to apply OPs?
– No (0) 76 67
– Yes (1) 38 33
How long have you worked as an agricultural worker?
– 10 years or less 42 37
– More of 10 years 72 63
Do you use a tractor operated nebulizer or pump to apply OPs?
– No (0) 99 87
– Yes (1) 15 13
Use of PPE in hands
– Yes (0) 69 61
– No (1) 45 39
Use of respiratory PPE
– Yes (0)
– No (1)
69
45
61
39
– Yes (0)
– No (1)
Use of protective eyewear
67 59
47 41
Use of PPE in the body
– Yes (0) 67 59
– No (1) 46 40
Use of PPE in the head
– Yes (0) 53 47
– No (1) 61 53
Frequency of use of PPE
– Always (0) 27 24
– Never or occasionally (1) 87 76
Use of PPE in the feet
– Yes (0) 45 40
– No (1) 69 60
In our workplace we have washbasin
– Yes (0) 65 57
– No (1) 49 43
In our workplace, we have toilet
– Yes (0) 75 66
– No (1) 39 34
In our workplace we have showers
– Yes (0) 62 54
– No (1) 52 46
In our workplace we have drinking water
– Yes (0) 52 46
– No (1) 62 54
In our workplace, we have hot water
– Yes (0) 70 61
39
– No (1) 44
(Continued)

Table 2 shows the 37 items summarized in four factors extracted after the Varimax rotation.
This factorial model accounts for 68% of the variance; factorial loads were greater than 0.20
and each factor has more than three reactants. Factor 1 presents the highest number of variables
with interactions. Factor 1 is dominated by variables related to pesticide application. Factor 2
summarized variability related to use of personal protective equipment. Factor 3 is directly related
Table 1. (Continued).
Percentage
response
Use organophosphate pesticides at home 13 11
– No (0)
– Yes (1) 99 87
Approximate distance from farm to house (in m) 18 16
– More of 500 m
– 500 m or less 96 84
Do you have a greenhouse, orchard or ﬁeld at home? 37
– No 42
– Yes 71 62
Table 2. Factorial analysis of the questionnaire to assess organophosphate pesticide exposure (variance explained = 68%).
Extraction method: principal component analysis. Rotation method: Varimax with Kaiser normalization.
Variables
Factors
1 2 3 4
Are you currently working applying pesticides? 0.990
When was your last pesticide application? 0.964
Do you work as a seasonal or permanent pesticide applicator? 0.947
Do you have a pesticide applicator license? 0.939
Do you eat, drink or smoke during the application? 0.931
Do you change your clothes after the application? 0.896
The place where pesticide is mixed is 0.892
Do you use manual pump backpack to apply OPs? 0.890
What type of OP do you recall applying? 0.884
Do you wear personal protective equipment when mixing? 0.878
Do you know the health risks you are exposed to when applying or mixing pesticides? 0.876
How many years have you applied pesticides? 0.863
How long does it take between the end of the application and taking a shower or bath? 0.855
During or after pesticide application, do you wash your hands before smoking, eating or
drinking?
0.845
If you change your clothes after work, where do you do it? 0.841
Are you trained on the health risks of pesticides? 0.830
Where do you wash the machinery? 0.790
Besides applying OPs, do you mix and prepare them? 0.789
Where do you store the pesticides? 0.739
Do you use a motorized pump backpack to apply OPs? 0.500
How long have you worked as an agricultural worker? 0.300
Do you use a tractor operated nebulizer or pump to apply OPs? 0.263
Use of PPE in hands 0.827
Use of respiratory PPE 0.808
Use of protective eyewear 0.795
Use of PPE in the body 0.778
Use of PPE in the head 0.747
Frequency of use of PPE 0.681
Use of PPE in the feet 0.660
In our workplace, we have washbasin 0.866
In our workplace, we have toilet 0.826
In our workplace, we have showers 0.785
In our workplace, we have drinking water 0.628
In our workplace, we have hot water 0.578
Use organophosphate pesticides at home 0.722
Approximate distance from farm to house (in meters) 0.679
Do you have a greenhouse, orchard or ﬁeld at home? 0.624

with hygienic workplace conditions related to OP exposure and factor 4 presents the home
conditions that facilitate exposure to OP in workers.
Table 3 presents the reliability analysis of the instrument. The questionnaire achieves an alpha
coefficient of Cronbach total = 0.95.
Cronbach’s alpha was greater than 0.70 for three of the four proposed factor groups (Table 3).
All correlations were positive and greater than zero. The weaker correlations were of the items
related to workplace and home conditions that facilitate OP exposure.
Table 4 shows the means, standard deviations, median, interquartile range, range, minimum,
and maximum scores of the questionnaire answered by the participants (maximum score 54
points) for each of the four factors.
The final composition of the questionnaire according to the four factors extracted and the
respective scores is shown in Appendix A2.
Table 3. Item-total correlations corrected, alpha value if the item is removed and alpha value per factor for the questionnaire.
Factor
Item-total correla-
tion correcteda
Alpha value
removes item
Alpha value
per factor
Factor 1: Labor conditions in the application of OPs 0.975
1. Are you currently working applying pesticides? 0.950 0.944
2. When was your last pesticide application? 0.917 0.942
3. Do you work as a seasonal or permanent pesticide applicator? 0.891 0.943
4. Do you have a pesticide applicator license? 0.856 0.943
5. Do you eat, drink or smoke during the application? 0.917 0.942
6. Do you change your clothes after the application? 0.880 0.943
7. What type of OP do you recall applying? 0.845 0.944
8. Where is the pesticide mixed? 0.834 0.944
9. Do you use manual pump backpack to apply OPs? 0.825 0.945
10. How many years have you applied pesticides? 0.831 0.943
11. Do you wear personal protective equipment when mixing? 0.730 0.944
12. Do you know the health risks you are exposed to when
applying or mixing pesticides?
0.757 0.944
13. How long does it take between the end of the application and
taking a shower or bath?
0.791 0.944
14. During or after pesticide application, do you wash your hands
before smoking, eating or drinking?
0.794 0.944
15. Are you trained on the health risks of pesticides? 0.859 0.943
16. If you change your clothes after work, where do you do it? 0.820 0.944
17. Besides applying OPs, do you mix and prepare them? 0.742 0.945
18. Where is the pesticide application equipment washed? 0.736 0.945
19. Where do you store the pesticides? 0.660 0.945
20. Do you use a motorized pump backpack to apply OPs? 0.492 0.946
21. Do you use a tractor operated nebulizer or pump to apply OPs? 0.273 0.948
22. How long have you worked as an agricultural worker? 0.268 0.948
Factor 2: Use of PPE 0.891
23. Use of PPE to protect hands (e.g. gloves) 0.243 0.948
24. Use of PPE to protect the head (e.g. face mask, hood) 0.120 0.949
25. Use of protective eyewear 0.229 0.948
26. Use of respiratory PPE (e.g. respirator) 0.333 0.947
27. Use of PPE to protect your body (e.g. coveralls, Tyvek suit) 0.357 0.947
28. Frequency of use of PPE 0.283 0.948
29. Use of PPE to protect the feet (e.g. rubber boots) 0.412 0.947
Factor 3: Workplace conditions that prevent exposure to OP 0.848
30. In our workplace we have showers 0.144 0.948
31. In our workplace we have washbasin 0.110 0.949
32. In our workplace we have hot water 0.100 0.949
33. In our workplace we have drinking water 0.100 0.949
34. In our workplace we have toilet 0.100 0.949
Factor 4: Home conditions related to OP exposure 0.600
35. Do you have a greenhouse, orchard or field at home? 0.100 0.949
36. Approximate distance from farm to house (in meters) 0.100 0.948
37. Use organophosphate pesticides at home 0.121 0.948
a
Indicates the linear correlation between each question and the total score obtained in the questionnaire.

Discussion
We evaluated the psychometric properties of a questionnaire to characterize potential OP expo-
sure. We identified four factors with the PCA extraction method. The items were grouped as
follows: the working conditions in the application of OP in agricultural workers (factor 1); use of
personal protective elements on the part of farmers (factor 2); sanitary workplace conditions that
prevent exposure to OP (factor 3) and home conditions related to OP exposure in the workers
(factor 4), which represented 68% of the total variance. These factors were reliable and internally
consistent, with a reliability greater than 75% in the first three factors and 60% in the fourth
factor.
Within these factors, it was found relevant to leave the items comprising a moderate correla-
tion with the total (Table 3), considering that if the element was removed, the change in
Cronbach’s alpha of each factor was not significant. Also, the content evaluated for those items
may provide relevant background information for evaluating exposure to OPs, such as the
questions of the factors 3 and 4, given that there are other exposure pathways which are related
to the variables of occupational exposure to OP (Lekei et al. 2014; Muñoz-Quezada et al. 2016a;
Corral et al. 2017), especially for applicators (Gesesew et al. 2016).
This questionnaire represents a first effort towards the future development of a standar-
dized version, with test–retest reliability and criterion related validity (compared to biomar-
kers) as a complementary measure regarding the exposure to pesticides on agricultural
workers.
The resulting contents from this first version coincide with other validated instruments, which
aim to assess exposure to pesticides related to the use of PPE and exposure conditions for
applicators and nonapplicators (Engel et al. 2001; Lekei et al. 2014; Gesesew et al. 2016).
However, this questionnaire has the advantage of including specific items to evaluate OP exposure
mainly related to occupational conditions of workers.
A questionnaire developed by Lekei et al (2014) demonstrated to be valid and useful for
inquiring about broad categories of pesticides and those of common use. However, the workers
showed difficulties in recalling the most specific active compounds of pesticides. The authors
mentioned that this was influenced by the information that was communicated by the authorities
about the hazardousness of the pesticides to the workers at that time. Also, we would add that in
general, the agricultural population has less access to formal education, which should be con-
sidered as an important factor when elaborating the items of the questionnaires. In this sense, in
addition to including an open question about the use of pesticides, we propose considering the
specific names of the pesticides in order to facilitate that the workers can recall them. In this
study, our purpose was to develop an instrument that aims to specifically assess organophosphate
exposure. In the same way, we believe that specific questionnaires should be proposed for other
pesticides too, in order to avoid confusing the respondent among different substances types and
classifications.
Gesesew et al. (2016) and Corral et al. (2017) showed in their studies that the use of
questionnaires on knowledge and attitudes regarding exposure to pesticides allows to assess the
Table 4. Descriptive statistics for the total score and the four factors of the questionnaire of exposure to OPs in farm workers
(n = 114).
Maximum N Values
Indicators Score Items Mean SD Median (IQRa
) Range Minimum Maximum
Total score 54 37 25.8 13.7 32 (25.3) 45 1 46
Factor 1 39 22 17.8 12.7 26 (27) 32 0 32
Factor 2 7 7 3.5 2.6 3 (5.3) 7 0 7
Factor 3 5 5 2.2 1.9 2 (4) 5 0 5
Factor 4 3 3 2.3 0.9 3 (1) 3 0 3
a
IQR = interquartile range.

behaviors associated with self-care practices, the beliefs about the effects on health and workers’
risk perception, providing useful inputs to the authorities for decision-making about workers’
training and vigilance strategies of the terrestrial application of pesticides.Compared to these
valuable previous efforts, our study provides more specific questions about the use of PPE, the
exposure of seasonal workers and pesticide applicators, the exposure at home and the conditions
of hygiene at work. Also, we included a series of questions that aim to identify acute and chronic
symptoms of exposure.
A limitation of our study is related to the fact that we were not able to compare the
questionnaire results with direct biomarkers of exposure to evaluate the sensitivity and specificity
of this instrument. Thus, this instrument is intended only as a descriptive measure of potential OP
exposure in agricultural workers. Further evaluation using biomonitoring is needed to verify OP
exposure assessed through the proposed questionnaire.
In summary, this OP exposure questionnaire is a valid instrument to evaluate potential
occupational exposure and provide information on working conditions and housing. The epide-
miological analysis of the association between exposure to OPs evaluated through this question-
naire and the health conditions is presented in another published article (Muñoz-Quezada et al.
2017). In addition, it allows the provision of timely information to guide public and private
institutions that can take action to control risk behaviors and provide oversight of situations that
imply noncompliance with current regulations, aiding to an adequate protection of the workers’
health.
Acknowledgments
The authors acknowledge the support of the National Commission of Scientific and Technological Research,
CONICYT of Chilean Government, Catholic University of Maule, the School of Public Health, University of
Chile, the Agricultural Development Institute (INDAP) of Curicó and Ministerial Secretariat of Health of the
Maule Region.
Disclosure statement
No potential conflict of interest was reported by the authors.
Funding
This work was supported by Fondo Nacional de Investigacion y Desarrollo en Salud under Grant SA13I20019; and
Fondo Nacional de Desarrollo Científico y Tecnológico under Grant11150784, of the National Commission of
Scientific and Technological Research, CONICYT of Chilean Government
Statements of authorship
María Teresa Muñoz-Quezada, Boris Lucero, Asa Bradman, Brittney Baumert, Verónica Iglesias, María Pía
Muñoz and Carlos Concha developed the concept and designed this work. María Teresa MuñozQuezada, Boris
Lucero, Brittney Baumert, Carlos Concha and María Pía Muñoz, participated in data collection. All authors
participated in the analysis and interpretation of data, drafting the manuscript, critical revision of the text and
approval of the final version.
ORCID
María Teresa Muñoz-Quezada http://orcid.org/0000-0002-8008-8625
Verónica Iglesias http://orcid.org/0000-0002-1636-9203

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Personalandhealthhistory
1.Birthdate:2.Age:
3.Sex:1.___Female2.___Male
4.Homeaddressandcommuneoforigin(writeit):
5.Placeofworkandcommune(writeit):
6.Phonenumber:
7.Maritalstatus(checkwithanX):1.___Married2.___Single
3.___Cohabitantpartner4.___Widow
5.___Separateordivorced
8.Doyouworkasaseasonalworkeroranagriculturalworker?(checkwithanX):1.___Yes2.___No
9.Doesyourpartnerworkonfarming?(checkwithanX):1.___Yes2.___No
10.Whatlevelofeducationdoyouhave?(checkwithanX):1.___Illiterate2.___Incompleteelementary
3.___Elementarycomplete4.___Incompletehighschool
5.___Highschoolcomplete6.___Technicalstudies
7.___Incompletecollege8.___Collegecomplete
11.Whatistheapproximatefamilyincome?(Write):
12.Howmanypeople(childrenandadults)liveinthehome?(Write):
13.Doyouhaveamental,physical,sensoryorpsychiatricdisability?(checkwithanX):1.___Yes2.___No
14.Ifyouareawoman,areyoupregnant?(checkwithanX):1.___Yes2.___No
15.Druguse(checkwithanX):1.___Yes2.___No
16.___Doyouhavesomeofthefollowinghealthconditions?(checkwithanX):
1.___Anemia2.___Diabetes3.___Kidneydamage4.___LiverDamage5.___Epilepsy6.___Skinallergyordermatosis
7.___Asthma8.___Cancer9.__Depression10.___Hypertension11.___HeartDisease12.___Anxiety
17.Drinkalcohol?(checkwithanX):0.No1.YesHowmanydrinksaweek?:
18.Doyousmoke?(checkwithanX):0.No1.YesHowmanycigarettesaweek?:
19.Doyouhavechildrenwithcongenitalmalformations?(checkwithanX):1.___Yes0.No
20.Areyouanagriculturalworkerorworkintheﬁeld?(checkwithanX):1.___Yes0.No
21.Whatisyourhealthcareplan?(checkwithanX):1.___Governmenthealthcare
2.___Privateinsurer
3.___None
4.___Donotknow
5.___Other
¿Whichone?=_______________
22.Areyoucoveredbyaworkplacesafetyandinsuranceagency?(checkwithanX):0.___Yes
1.___No
2.___Donotknow
(Continued)
AppendixA1.Sociodemographicdataandgeneralhealthconditions

(Continued).
Personalandhealthhistory
23.Ifyouareanagriculturalworker,haveyoubeengivenacetylcholinesterasetestsin
yourworkinthepastyear?(checkwithanX):
0.___Notapplicable
1.___Yes
2.___No
24.Whatweretheresultsofthetests?(checkwithanX):0.___Notapplicable
1.___Normal
2.___Abnormalreport
3.___Didnotreceiveresults
25.DuringthelastperiodthatyouwereexposedtoOPsforyouragriculturalwork,didyoueverpresentanyofthefollowingsymptomsorsigns?(checkwithanX):
1.___Dizziness2.___Nausea3.___Fatigue4.___Vomiting5.___Headache6.___Abdominalpain
7.___Diarrhea8.___Shortness
ofbreath
9.___Legweaknessand/orcramps10.___Skininjuries11.___Insomnia12.______Nightsweats
13.___Blurry
vision
14.___Salivation15.___HasbeenintoxicatedwithOP16.___HasbeenhospitalizedforOPpoisoning
26.Ifyouareanapplicator,namethepesticidesyouapplyatworkWritethenameshere:

Appendix A2. Final structure of the exposure questionnaire with the items grouped in the four rotated factors.
Factor 1: Labor conditions in the application of OPs
1.How long have you worked as an agricultural
worker?
0.___10 years or less 1.___More than 10 years
2.Are you currently working applying pesticides? 1.___Yes 0.___No
3.When was your last pesticide application? 0.___Not applicable 1.___2 years or more
2.___Less than 2 years
4. Do you work mostly as a seasonal or permanent
pesticide applicator? (Check one)
0.___Not applicable 1.___Seasonal
2.___Permanent
5. How many years have you applied pesticides? 0.___Not applicable 1.___10 years or less
2.___More than 10 years
6. Do you have a pesticide applicator license? 1.___Yes 0.___No
7. Do you know the health risks you are exposed to
when applying or mixing pesticides?
1.___Yes 2.___No 0.___Not applicable
8. Are you trained on the health risks of pesticides? 1.___Yes 2.___No 0.___Not applicable
9. Do you eat, drink or smoke during the
application?
1.___No 2.___Yes or
occasionally
0.___Not applicable
10.During or after pesticide application, do you
wash your hands before smoking, eating or
drinking?
1.___Yes 2.___No or
occasionally
0.___Not applicable
11.What type of pesticide do you recall applying?
(Can check more than one option)
(Internal code for answers rating: 0 = Not
applicable; 1 = Only one OP; 2 = More than one
OP)
0.___Not applicable OP 1.___Chlorpyrifos (Lorsban,
Troya)
2.___Methamidophos
(MTD 600, Monitor, Tamaron)
3.___Azinphosmethyl
(Gusathion)
4.___Metidation 5.___Diazinon
6.___Phosmet 7.___Dimethoate
8.___Profenofos 9.___Cadusafos
10.___Other OP (Name them): _________
12.Do you use manual pump backpack to apply
OPs?
1.___Yes 0.___No or not applicable
13.Do you use a motorized pump backpack to apply
OPs?
14. Do you use a tractor operated nebulizer or pump
to apply OPs?
15. Where do you wash the machinery that was
used to apply pesticides? (Check one option)
0.___Does not wash, not applicable 1.___In a dedicated place
for washing
2.___Yard, orchard, pasture or ﬁeld 3.___Inside the house
16. Where do you store the pesticides? (Check one
option)
0.___Not applicable 1.___Warehouse at home
or work
2.___In the house’s yard 3.___Inside the house
17. Besides applying OPs, do you mix and prepare
them?
1.Yes 0.___No or not applicable
18. The place where the pesticide is mixed is. 0.___Not applicable 1.___Open 2.___Closed
19. Do you wear personal protective equipment
when mixing?
0.___Not applicable 1.___Yes 2.___No
20.Do you change your clothes after the
application?
1.___Yes 2.___No or
occasionally
0.___Not applicable
21.If you change your clothes after work, where do
you do it? (check one option)
1.___Work 2.___Home 0.___Not applicable
22.How long does it take between the end of the
application and taking a shower or bath? (check
one option)
1.___Less than 15 min 2.___15 min or mores
0.___Not applicable
Factor 2: Use of PPE
In your work as an agricultural worker, check if
you use the following personal protective
equipment (PPE):
23.Use of PPE in hands (gloves) 0.___Yes 1.___No
24. Use of PPE in the head (hat) 0.___Yes 1.___No
25. Use of protective eyewear (googles, face shield
or safety glasses)
0.___Yes 1.___No
26. Use of respiratory PPE (respiratory mask with
recommended ﬁlters and facial protection)
0.___Yes 1.___No
27. Use of PPE in the body (waterproof suit with no
cuts or holes)
0.___Yes 1.___No
28. Use of PPE in the feet (rubber boot) 0.___Yes 1.___No
(Continued)

Appendix A2. (Continued).
Factor 1: Labor conditions in the application of OPs
29. Frequency of use of PPE 0.___Always 1.___Never or occasionally
Factor 3: Workplace conditions that prevent exposure
to OP
30.In our workplace, we have showers 0.___Yes 1.___No
31.In our workplace, we have washbasin 0.___Yes 1.___No
32.In our workplace, we have hot water 0.___Yes 1.___No
33.In our workplace, we have drinking water 0.___Yes 1.___No
34. In our workplace, we have toilet 0.___Yes 1.___No
Factor 4: Home conditions related to OP exposure
35. Do you have a greenhouse, orchard or ﬁeld at
home?
0.___Yes 1.___No
36. Approximate distance from farms to your house
(in meters) (Check one option)
0.___More than 500 m 1.___500 m or less
37. Use organophosphate pesticides at home 0.___Yes 1.___No

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