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The Prospective Investigation of Pesticide Applicators’ Health (PIPAH) Study: baseline volunteer cohort
Prepared by the Health and Safety Executive
RR1119 Research Report
© Crown copyright 2017 Prepared 2015 First published 2017 You may reuse this information (not including logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view the licence visit www.nationalarchives.gov.uk/doc/open-government-licence/, write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email [email protected]. Some images and illustrations may not be owned by the Crown so cannot be reproduced without permission of the copyright owner. Enquiries should be sent to [email protected]. This report and the work it describes were funded by the Health and Safety Executive (HSE) and the Department for Environment, Food and Rural Affairs (DEFRA). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE or DEFRA policy.
There are concerns that some pesticides may have levels of human toxicity that cause chronic health problems in workers who apply them, for instance cancers and neurological conditions. However, the evidence base linking worker exposure to pesticides and the development of adverse health outcomes is inconclusive. It is important to improve this evidence base so that any risks to worker health are understood and can be effectively controlled. The Prospective Investigation of Pesticide Applicators’ Health (PIPAH) Study is a long-term volunteer study established to develop a more complete understanding of how pesticide exposure potentially affects the health of workers. This report describes key features of the baseline cohort of 5,731 volunteers recruited to the PIPAH Study in 2013 to September 2014, the main recruitment period. The volunteers are workers who are professional and licensed GB pesticide users. The key features described are: demographics; health as compared to data on the general public from a large number of English General Practices; and ‘lifestyle’ data on diet, alcohol and smoking. PIPAH is a prospective cohort study: volunteers are recruited into the study, and factors that may be relevant to the development of disease will be measured over a number of years. The background to the PIPAH Study and its rationale and design are described in report RR1103.
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David Fox, Dr Anne-Helen Harding and Gillian Frost Health and Safety Executive Harpur Hill Buxton Derbyshire SK17 9JN
The Prospective Investigation of Pesticide Applicators’ Health (PIPAH) Study: baseline volunteer cohort
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KEY MESSAGES
The aims of the Prospective Investigation of Pesticide Applicator’s Health (PIPAH) Study are to investigate potential associations between occupational exposure to pesticides and:
• changes in chronic ill health status over time, including the development of newchronic health conditions such as respiratory, neurological, circulatory, ophthalmic,dermatological and musculoskeletal; and
• all-cause mortality (ie deaths from all causes) and cancer incidence.
It is a volunteer study of men and women who apply pesticides as a part of their job. More specifically, the study participants are pesticide applicators in Great Britain (GB) who are certified under the 1986 Control of Pesticides Regulations, or who were born before 1965 and apply pesticides under ‘grandfather rights’.
The main recruitment phase took place in 2013-2014; during that time 5731men and women agreed to take part in the study. This represents a 20 % recruitment rate. Further recruitment is on-going.
The study participants completed a detailed questionnaire providing information on demographics; work history; past use of pesticides; family medical history; self-reported ill-health; lifestyle factors such as physical activity and diet; and social circumstances.
The large majority of participants work in the agricultural sector; however significant numbers also report working in the amenity and forestry sectors.
This is a follow-up study and participants will be invited to complete further questionnaires. The questionnaires will cover new areas, for example more in-depth questions on specific health outcomes or of pesticides used, and some questionnaires will up-date the information provided at baseline. Cancer and death registration data will be requested from the NHS central bodies for the participants who consented to this part of the follow-up.
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EXECUTIVE SUMMARY
Background: PIPAH Study aims and design
The aims of the Prospective Investigation of Pesticide Applicator’s Health (PIPAH) Study are to investigate associations between occupational exposure to pesticides and:
• changes in chronic ill health status over time, including the development of newchronic health conditions such as respiratory, neurological, circulatory, ophthalmic,dermatological and musculoskeletal; and
• all-cause mortality (ie deaths from all causes) and cancer incidence
PIPAH is a volunteer prospective cohort study. In this type of study, volunteers are recruited into the study, and factors that may be relevant to the development of disease are assessed. The study members are followed-up over time to see if they develop the disease of interest. The study is designed specifically to collect comprehensive data around worker exposure levels, health and medical history, employment history, and potential confounding factors such as smoking and diet. This report describes key features of the baseline cohort of volunteers recruited to the PIPAH Study.
Recruitment and response rates
The target population of the PIPAH study is pesticide applicators in Great Britain (GB) who are certified under the 1986 Control of Pesticides Regulations, or who were born before 1965 and apply pesticides under ‘grandfather rights’. The main wave of recruitment for the PIPAH study cohort was conducted in two phases. In the first phase in early 2013, members of either the National Register of Sprayer Operatorsa (NRoSO) or the National Amenity Sprayer Operators Registerb (NAsOR) were invited to take part in the study. A second recruitment wave was undertaken in early 2014 where members of the Pesticide Users’ Health Studyc (PUHS) were invited to participate in the PIPAH study. Altogether 5731 men and women agreed to take part in the study.
Recruitment wave Response rate
(percent) January 2013 (NRoSO/NAsOR) 19 March 2014 (PUHS) 22 Total 20
a https://www.nroso.org.uk/, Accessed 13/02/2015 b http://www.nasor.org.uk/, Accessed 13/02/2015 c http://www.hsl.gov.uk/resources/major-projects/puhs, Accessed 13/02/2015
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Summary of key demographic data
Age: the mean age of cohort members is 54 years, with a median age of 55 years. The majority of the cohort members are aged between 40 and 70 years. This compares to a mean age of 39 (median 39 years) for males aged 16-64 years in England and Wales, based on data from the 2011 Censusd. Sex: the cohort is 98% male. Residential tenure: 73 % report that they own their home, either outright or on a mortgage. Marital status: 74 % of the cohort are married. Household size: the majority of the cohort (60 %) reports their household size as consisting of 2 adults. Qualifications: 86 % report having a formal qualification, with the largest proportion reporting their qualification as being in the “other” category i.e. not a degree/higher, A levels or GCSE/O-level. Employment status: most of the cohort is either self-employed (52%) or employed (36%).
Summary of lifestyle data
Diet: 9.5 % of the cohort (based on 3050 responses) usually ate at least five portions of fruit and vegetables per day, 99 % report eating red or processed meat less than once a day and 62 % of the cohort (based on 3508 responses) report eating oily fish at least once a week. Smoking: 9 % of the cohort report that they are a current smoker, 28 % are former smokers and 63% report never having smoked. This compares to Health and Social Care Information Centre statistics for England of 19 %, 25 % and 56 % respectively.e Alcohol: 94 % report that they currently drink alcohol.
d https://www.nomisweb.co.uk/census/2011/ks102ew, Accessed 13/03/2015 e http://www.hscic.gov.uk/catalogue/PUB11454, Accessed 13/02/2015
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CONTENTS
KEY MESSAGES…………………………………………………4
EXECUTIVE SUMMARY…...……………………………………5
1. INTRODUCTION ............................................................................. 8
2. THE PIPAH STUDY POPULATION ............................................ 9
3. SUMMARY OF KEY BASELINE DATA ................................... 11 3.1 Cohort demographics 11 3.2 Lifestyle factors 17 3.3 Health outcomes 20
4. SUMMARY AND CONCLUSIONS ............................................. 21
5. REFERENCES ................................................................................ 22
6. APPENDIX: PIPAH GENERAL QUESTIONNAIRE ............... 23
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1. INTRODUCTION
Men and women using pesticides as a part of their job have the greatest potential for long-term exposure to the various active compounds present in pesticides. These workers are likely to regularly handle at least one or more type of pesticide in the course of their work, and thus have a higher risk of exposure to active pesticide compounds compared to the general population. Exposure to pesticides in occupational settings could impact adversely on the long-term health of workers should such exposures increase the risk of developing certain health outcomes.
The Prospective Investigation of Pesticide Applicators’ Health (PIPAH) Study is a prospective cohort study designed and administered by the Health and Safety Executive’s Buxton laboratory. The overall aims of the PIPAH study are to monitor the long-term health of occupational pesticide users and to investigate potential associations between long-term pesticide use and health. Complementing similar studies such as the Agricultural Health Studyf in the United States, and by building on previous work by the Pesticide Users’ Health Studyg (PUHS) in Great Britain (GB), the PIPAH study will seek to generate a more complete understanding of the potential relationships between pesticide use/exposure and a broad range of health outcomes. Circumstantial factors such as lifestyle factors including smoking and diet, type and duration of employment, and the use/non-use of personal protective equipment (PPE) will be taken into account when investigating these relationships. Of particular interest are the different types of pesticides applied by pesticide users, the time periods and duration of application and also the equipment and application methods used.
New cohort members were asked to complete the PIPAH study baseline General Questionnaire, a copy of which is presented in Appendix 1. A more comprehensive description of the design of the PIPAH study and its rationale are contained in a separate HSE report ‘The PIPAH Study: Background, Design and Rationale’1. Recruitment of new members through the National Register of Sprayer Operators (NRoSOh) is ongoing, but the main recruitment wave is now complete. The aim of this report is to describe the characteristics of the cohort for study members recruited up until September 2014.
f http://aghealth.nih.gov/ , Accessed 13/02/2015 g http://www.hsl.gov.uk/resources/major-projects/puhs , Accessed 13/02/2015 h https://www.nroso.org.uk/, Accessed 13/02/2015 8
2. THE PIPAH STUDY POPULATION
The target population of the PIPAH study is pesticide applicators in Great Britain (GB) who are certified under the 1986 Control of Pesticides Regulations, or who were born before 1965 and apply pesticides under ‘grandfather rights’. The intention of the PIPAH study was to recruit a cohort of several thousand GB based pesticide applicators in as wide a range as possible of occupations and employment sectors.
The main wave of recruitment for the PIPAH study cohort was conducted in two phases. In the first phase in early 2013, members of either the National Register of Sprayer Operators (NRoSO) or the National Amenity Sprayer Operators Registeri (NAsOR) were invited to take part in the study. The NRoSO and NAsOR databases are central registers of pesticide sprayer operators in GB who use continuing professional development in order to ensure ongoing competence. These registers include both certified pesticide users and those applying pesticides under ‘grandfather rightsj’.
In the second recruitment phase in early 2014, members of the Pesticide Users’ Health Studyk (PUHS) were invited to participate in the PIPAH study. The PUHS is a long-term follow-up study that was established by HSE in the late 1990s. It comprises around 65,910 men and women who are certified pesticide users and who agreed to take part in the Health and Safety Executive’s (HSE’s) medical research program. Although the PUHS participants have been followed-up for long-term health outcomes, little other than basic demographic information has been collected on most of the PUHS participants. During 2004-2006, members of the PUHS were invited to complete a pesticide usage questionnaire; of the 65,000 study participants contacted, 9,294 completed and returned the pesticide usage questionnaire. Respondents to this pesticide usage questionnaire were also invited to take part in the PIPAH study. After accounting for deaths and emigrations subsequent to the study commencing, this resulted in 7,597 PUHS members being contacted for recruitment into the PIPAH study.
Approximately 21,000 members of NRoSO and NAsOR, and the 7,597 PUHS members were sent a survey pack inviting them to participate in the PIPAH study. The packs contained an information leaflet, questionnaire, consent form and a postage paid envelope for the return of completed questionnaires. A reminder was sent out after the initial invitation. In the first recruitment phase, a reminder postcard was sent to everyone a week after the first invitation pack. In the second recruitment phase, a full survey pack was sent four weeks after the first invitation to everyone who had not responded up to that point.
In addition to the two main recruitment phases, rolling recruitment (in which all new members of NRoSO and NAsOR are invited to take part in the PIPAH study) is ongoing. Recruitment activities have resulted in the collection of baseline data from 5,731 GB based pesticide applicators. This figure includes members recruited at all stages, including rolling recruitment. Questionnaires could be completed either online, or by using the paper version included in the survey pack. All data gathered using paper versions of the questionnaire were entered manually into the study database by an external contractor.
Table 1 summarises the numbers of cohort members recruited during the different recruitment phases, the number of recruitment invitations issued and response rates.
i http://www.nasor.org.uk/, Accessed 13/02/2015 j Acquired rights not to need to undertake training for those born before 31/12/1964 k http://www.hsl.gov.uk/resources/major-projects/puhs , Accessed 13/02/2015 9
Table 1 Recruitment data and overall response rates
Recruitment wave Number invited
Number recruited
Response rate
(percent)
January 2013 (NRoSO/NAsOR) 21051 3948 18.8 January 2014 (rolling recruitment NRoSO) 107 March 2014 (PUHS) 7597 1,676 22.1 Total 28648 5731 20.0
Table 1 shows clearly that the cohort is comprised of just over two thirds NRoSO/NAsOR recruits with a response rate of just under 19 %. At just over 22 %, the response rate for PUHS recruits was marginally higher. The overall response rate was 20 %.
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3. SUMMARY OF KEY BASELINE DATA
3.1 COHORT DEMOGRAPHICS
3.1.1 Age and sex
The age of cohort members is distributed in a relatively symmetric pattern around a mean age of 54.2 years and a median age of 54.6 years. The majority of the cohort members are aged between 40 and 70 years. This compares to a median age of 39 years for males aged 16-64 years in England and Wales, based on data from the 2011 Censusl. The cohort age distribution pattern is illustrated as a histogram in Figure 1.
Figure 1 Histogram describing the PIPAH cohort age distribution
The age distribution of the cohort differs from that of the general working age population, with the cohort having a mean age 14.8 years greater. The cohort age distribution peaks in the mid-fifties, well into the age range typically regarded as ‘middle-age’. The risk of developing some health outcomes (e.g. cancer) increases with age, and so the age structure of the cohort will need to be considered in the analysis of health outcome data. Table 2 summarises the mean and median ages of cohort members for the three recruitment waves for the study. At 60.0 years, the mean age of PUHS recruits is almost 8 years higher than that of NRoSO recruits.
Table 2 Age in years by cohort sub-group
Number Mean Median Inter-quartile range
NRoSO 3989 51.8 52.6 15.7 NAsOR 29 53.2 55.2 10.2 PUHS 1654 60.0 60.7 16.6 Total 5672 54.2 54.6 16.6 Missing 59
l https://www.nomisweb.co.uk/census/2011/ks102ew, Accessed 13/03/2015
010
020
030
040
0Fr
eque
ncy
20 40 60 80 100Age at baseline
11
Figure 2 compares the PIPAH cohort age structure with the age structure of the NRoSO and NAsOR databases. It is clear that overall there is a strong similarity and symmetry of age structure.
Figure 2 Age structure comparison between the PIPAH cohort and NRoSO/NAsOR databases
Table 3 summarises comparisons between the proportion of women in the NRoSO/NAsOR sampling frame and the proportion of women in the crop, animal production and hunting occupational division of the 2012 Labour Force Survey. Clearly, the proportion of women recorded by the LFS in crop and animal production exceeds that in the PIPAH study sampling frame by a significant margin, indicating that the pesticide applicator population has a higher proportion of men than is typical of crop and animal production workers.
Table 3 Comparison of the sex distribution between the NAsOR/NRoSO sampling frame and Industry Division 01 from the 2012 Labour Force Survey (LFS)
NAsOR/NRoSO sampling frame
LFS 2012m Industry Division 01 – crop, animal production and huntingn occupations
Number Percent Number Percent
Male 20819 99.4 219680 74.2
Female 129 0.6 76584 25.8
Total 20948 100.0 296264
Missing 104
Table 4 compares the sex distribution of the cohort with that of the study population. Table 4 clearly shows that the proportions of males and females in the cohort is close to the male-female
m http://www.ons.gov.uk/ons/guide-method/method-quality/quality/quality-information/labour-market/index.html, Accessed 11th February 2015 n Includes both employed and self employed
65-69
50-54
60-64
75+
55-59
70-74
30-34
35-39
45-49
40-44
25-29
<25
Age
gro
up (y
ears
)
20 15 10 5 0 5 10 15 20Percent
Study population
NRoSO/NAsOR
12
proportions in the sampling frame, suggesting that the cohort is reasonably representative of the members of the pesticide sprayer population who were invited to participate in the study. For the cohort overall, response rates for males and females are approximately similar at around 20 %. There was a difference in response rates for women in the NRoSO/NAsOR and PUHS cohort sub-groups, with the female response rate for the latter being around 12 percentage points lower. However, these differences disappear when the sub-groups are combined with the response rate for both men and women being around 20 %.
Table 4 Sex distribution and response rate by cohort sub-group
NRoSO/NAsOR
PIPAH cohort Study population Response rate
Number Percent Number Percent Percent
Male 3987 99.1 20820 99.4 19.1
Female 38 0.9 127 0.6 29.9
Total 4025 100.0 20947 100.0
Missing 30 104
PUHS
PIPAH cohort Study population Response rate
Number Percent Number Percent Percent
Male 1560 94.7 7103 93.5 22.0
Female 88 5.3 494 6.5 17.8
Total 1648 100 7597 100
Missing 28
Overall cohort
PIPAH cohort Study population Response rate
Number Percent Number Percent Percent
Male 5547 97.8 27923 97.8 19.9
Female 126 2.2 621 2.2 20.3
Total 5673 100 28544 100
Missing 58 104
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The small proportion of females in the cohort may be relevant to the interpretation of cohort data around diagnosed health outcomes, and will need to be considered when analysing these data. For example, numbers may be too small to undertake the analysis of female only health outcomes such as ovarian cancer. Caution will also need to be exercised when considering the data on health outcomes where there are known differences in the way the conditions manifest between males and females e.g. differences in prevalence, disease progress etc.
3.1.2 Personal circumstances
3.1.2.1 Marital status
Table 5 summarises the cohort by marital status. The largest marital status group were those who are married, representing almost three quarters of the cohort. The proportion of the sample reporting that they are married is almost 28 percentage points higher than that reported for England and Wales based on data from the 2011 Census.
A combined ‘never married’ and ‘living together’ percentage of 17.1 % from the PIPAH study cohort is approximately half of the equivalent ‘never married’ proportion reported in the census statistics. These comparisons suggest that the PIPAH cohort differs somewhat from the general population in this respect. Cohort members are more likely to be married compared to the England and Wales population generally.
Table 5 Marital status
Marital status PIPAH Study England and Waleso
Number Percent Percent Never married 529 9.5 34.6 Married 4161 74.3 46.6 Living together 424 7.6 Not categorised Widowed 112 2.0 7.0 Divorced or separated
303 5.4 11.6
Other 69 1.2 0.2 Total 5598 100.0 100.0 Missing 133
3.1.2.2 Residential tenure and household size Table 6 Home ownership and renting
Tenure PIPAH Study
England and Walesp
Number Percent Percent Own 4074 72.7 64.0 Rent 891 15.9 35.0 Other 638 11.4 1.0 Total 5603 100.0 100.0 Missing 128
o England and Wales Census 2011 http://www.ons.gov.uk/ons/dcp171778_290685.pdf, Accessed 13/02/2015 p England and Wales Census 2011 http://www.ons.gov.uk/ons/dcp171778_290685.pdf, Accessed 13/02/2015 14
Table 6 summarises the cohort residential tenure statistics and compares them with equivalent 2011 Census statistics for England and Wales. Just under three quarters of the cohort report that they own their own home (either outright or mortgaged). This proportion is about 9 percentage points higher than that reported in the 2011 Census for all individuals in England and Wales. At just under 16 %, the proportion of cohort members reporting that they rent their home is approximately half that reported in the 2011 Census.
The majority of the cohort (just over 60 %) report two adults as living in the household. Figure 3 summarises these data in chart format.
Figure 3 Number of adults in household
A majority of the cohort (1351) report that they have no children living at home. For those reporting the presence of children in their household, either one or two children are the most common number. Approximately 55 % of the cohort report the presence of one or more children in their household compared to 29 % as reported in the 2011 Censusq for England and Wales. However, there was a high proportion of missing data for this question among the PIPAH study members, i.e. 2735, or approximately 48 % of the cohort chose not to provide an answer. Figure 4 summarises these data in chart format.
q http://www.ons.gov.uk/ons/rel/census/2011-census-analysis/households-and-household-composition-in-england-and-wales-2001-2011/sty-facts-about-households.html, Accessed 13/02/2015
518
3124
945
483
9412 5
01,
000
2,00
03,
000
Tota
l num
ber
1 2 3 4 5 6 7Number of adults in household
15
Figure 4 Number of children in household
3.1.3 Qualifications
Table 7 summarises the cohort in terms of qualifications and compares it to equivalent data from the 2011 Census for England and Wales. Nearly 25 % of the cohort report achieving GCSE/O-level qualifications. Approximately 14 % of the cohort reported having no qualifications, nine percentage points less than the 23 % recorded for England and Wales in the 2011 Census. A little over 17 % of the cohort report achieving either a first or higher degree, less than the proportion of 27 % reported for England and Wales in the 2011 Censusr. Compared to England and Wales, the cohort has a lower proportion of individuals with no qualifications, and also a lower proportion of members reporting experience of post GCSE level education, including A-levels and higher education. By contrast, the cohort has almost 36 % reporting the possession of other (most likely vocationally based) qualifications, compared to 10 % of the census population.
Table 7 Highest level of qualification
Highest level of qualification
Number Percent 2011 Census England and Waless (percent)
No formal qualifications
798 14.4 23.0
GCSE/O-level or equivalent
1361 24.5 28.0
A-level or equivalent 428 7.7 12.0 Degree/higher degree 972 17.5 27.0 Other 1991 35.9 10.0 Total 5550 100.0 100.0 Missing 181
r http://www.ons.gov.uk/ons/dcp171778_290685.pdf, Accessed 13/02/2015
1351
652
755
179
456 5 1 1 1
050
01,
000
1,50
0To
tal n
umbe
r
0 1 2 3 4 5 6 7 8 10Number of children in household
16
3.1.4 Employment status
Table 8 summarises the employment status of the cohort. The majority of the cohort describe themselves as self-employed (at just over 52 %) compared with nearly 14 % in the population of England and Wales generally. Approximately 36 % of the cohort report that they are employed compared with almost 75 % for England and Wales. These differences are likely to be attributable to the high proportion of farmers in the cohort, many of whom are self-employed. The employment profile of the cohort is thus markedly different to the general population of England and Wales.
Table 8 Employment status
Employment status PIPAH Study
England and Walest
Number Percent Percent Employed 2031 36.3 74.9 Self-employed 2932 52.4 13.9 Student 8 0.1 4.9 Unemployed 12 0.2 6.3 Other 617 11.0 N/A Total 5600 100.0 100.0 Missing 131
3.2 LIFESTYLE FACTORS
The baseline questionnaire asked cohort members about a range of lifestyle factors, including physical activity, diet and consumption of tobacco and alcohol. These questions were included because lifestyle factors can act as potential confounding variables when considering the relationship between pesticide exposure and health outcomes.
3.2.1 Diet
Figure 5 summarises some of the important components of the diets of the PIPAH cohort. 9.5 % of the cohort (based on 3050 responses) usually ate at least five portions of fruit and vegetables per day. This compares to 30 % of adults in Britain meeting the government target of eating a minimum of five fruit and vegetable portions a dayu. Figure 5 also shows that 94 % of the cohort (based on 4962 responses) report eating red or processed meat less than once a day and 62 % of the cohort (based on 3508 responses) report eating oily fish at least once a week. Nutritional guidelines in the UK recommend that adults do not eat more than one 70 g portion of red or processed meat a day, and that they should eat two portions of fish, including one 140 g portion of oily fish, per week.
t http://www.ons.gov.uk/ons/dcp171778_290685.pdf, Accessed 13/02/2015 uhttps://www.gov.uk/government/uploads/system/uploads/attachment_data/file/310995/NDNS_Y1_to_4_UK_report.pdf, Accessed 16/03/2015 17
Figure 5 Frequency of fruit and vegetable, red and processed meat, and oily fish consumption
3.2.2 Smoking status
Table 9 summarises current and past smoking behaviour. 9 % of the cohort report that they currently smoke tobacco, while about 28 % report that they have smoked in the past. The cohort smoking rate is around half of the estimated 19 % smoking rate in Englandv.
Table 9 Smoking status
PIPAH cohort Englandw
Number Percent Percent
Never smoked 3311 63.4 56.0
Former smoker 1439 27.6 25.0
Current smoker 471 9.0 19.0
Total 5221 100.0
Missing 510
v http://www.hscic.gov.uk/catalogue/PUB11454, Accessed 13/02/2015 w General Lifestyle Survey 2011 http://www.hscic.gov.uk/catalogue/PUB11454 Statistics on Smoking, England - 2013, Additional tables: Table 1 [.xls], Tab 2.2 Accessed 13/02/2015
0 20 40 60 80Percentage of PIPAH study members
Oily fish
Red & processed meat
Fruit & vegetables
3 or more210
2 or more1Less than 10
13 or more9-125-83-4Less than 3
Portions of fruit & vegetables per day
Number of times red & processed meat eaten per day
Number of times oily fish eaten per week
18
3.2.3 Alcohol
Table 10 shows that 94 % of the cohort reported that they currently drink alcohol. This is around 10 percentage points higher than GB based comparator statistics taken from the ONS General Lifestyle Survey 2010 that report around 85 % of respondents are current drinkers. This suggests that the proportion of the cohort who are currently alcohol drinkers is slightly higher than the proportion for the population of GB.
Table 10 Cohort drinking status
PIPAH study General Lifestyle Survey, ONS , GB 2010x,y
Number Percent Percent Never drinker 122 2.2 N/A Former drinker 196 3.6 N/A Never drinker or not drunk in last year
N/A N/A 15
Current drinker 5132 94.2 85 Total 5450 100.0 100 Missing 281
Table 11 summarises data on units of alcohol weekly consumed, broken down by sex. To aid comparison with other statistics, the data for men and women are analysed using different categories of units consumed. The high proportion of missing data for the questions upon which these consumption statistics are based (over half of the total cohort size) makes it difficult to rule out the presence of response bias in the data. However, comparisons with broader estimated weekly alcohol data from the Health Survey for England 2011 provide a more reassuring picture. For men, comparisons between the cohort and the Health Survey for England reveal very similar proportions drinking under 21, between 21 and 50 and over 50 units of alcohol per week. The comparisons for women are also very similar, suggesting that the cohort estimates are comparable, despite the high proportion of cohort members who declined to report their alcohol consumption.
x General Lifestyle Survey 2010 http://www.ons.gov.uk/ons/rel/ghs/general-lifestyle-survey/2010/drinking.xls, table 2.5b Accessed 13/02/2015 y Based on reported average frequency alcohol consumption in previous year 19
Table 11 Reported weekly alcohol consumption in units
PIPAH study Englandz
Reported weekly consumption
Estimated weekly alcohol consumption
Alcohol units Number Percent Percent
Men Under 21 1567 72.7 77.0
21 to 50 399 18.5 18.0
Over 50 189 8.8 6.0
Total 2155 100.0 100.0
Missing 3392
Women Under 14 45 80.3 82.0
14 to 35 8 14.3 14.0
Over 35 3 5.4 4.0
Total 56
Missing 70
Grand totalaa 5673
3.3 HEALTH OUTCOMES
Cohort members were asked about a range of previously diagnosed health outcomes (excluding cancer) and also their age at diagnosis. Questions were asked about respiratory, neurological, circulatory, ophthalmic, dermatological, musculoskeletal and metabolic health outcomes. Table 12 provides summary statistics for these self-reported health outcomes and also the lifetime prevalence of each outcome in the cohort.
z Health Survey for England 2011 http://www.hscic.gov.uk/catalogue/PUB09300/HSE2011-Ch6-Drinking-Patterns.pdf, Table 6.11 Accessed 13/02/2015 aa This does not include the 58 cohort members who declined to report their gender status 20
Table 12 Cohort lifetime prevalence and diagnosis age of health outcomes (N =5731)
Health outcome Number in cohort reporting condition (n)
Cohort lifetime prevalence (%)
Cohort median age at diagnosis (years)
Lungs and airways Asthma 595 10.4 18 Chronic bronchitis 70 1.2 32 Chronic obstructive pulmonary disease 56 0.98 60 Emphysema 10 0.17 55 Farmer’s lung 26 0.45 35 Pleurisy 96 1.7 32 Pneumonia (viral or bacterial) 217 3.8 40 Pulmonary fibrosis* <5 <0.087 47 Sarcoidosis 20 0.35 45.5 Tuberculosis 13 0.23 8 Other chest conditions 118 2.06 45 Nervous system Alzheimer’s disease* <5 <0.087 51 Anxiety 229 4.0 41 Depression 347 6.05 40 Depression requiring medication or shock therapy 183 3.2 40 Epilepsy 34 0.59 24 Motor neurone disease* <5 <0.087 41 Multiple sclerosis 16 0.28 39 Parkinson’s disease 23 0.4 60.5 Other neurological problems 131 2.29 48 Heart and blood vessels Angina 122 2.13 57 Arrhythmia 183 3.19 52 High blood pressure requiring medication 848 14.8 53 Myocardial infarction 96 1.68 57 Stroke 67 1.17 58 Muscles and skeleton Lupus or SLE 6 0.10 44 Rheumatoid arthritis 224 3.91 50
21
Health outcome Number in cohort reporting condition (n)
Cohort lifetime prevalence (%)
Cohort median age at diagnosis (years)
Scleroderma 5 0.09 45.5 Work related back, neck or shoulder injury 1345 23.47 34.5 Eyes Cataracts 182 3.18 63.5 Detached retina 49 0.85 40 Glaucoma 79 1.38 54 Retinal or macular degeneration 49 0.85 55 Skin Acne 149 2.6 15 Eczema (or atopic dermatitis) 383 6.68 18 Shingles 411 7.17 40 Other skin problems 262 4.57 40 Diabetes and thyroid gland Diabetes (not related to pregnancy) 244 4.26 54.5 Goitre 6 0.10 49 Thyrotoxicosis/Grave’s disease 13 0.23 36.5 Other thyroid diseases 75 1.31 46 Kidneys Chronic kidney infections or pyelonephritis 18 0.31 45.5 Kidney failure requiring dialysis or transplant 7 0.12 41.5 Kidney stones 214 3.73 42 Nephritis, or nephrosis 12 0.21 15 Other kidney disease 44 0.77 54 Liver - liver function problems 58 1.01 49 Other conditions Glandular fever 302 5.27 20 Lead poisoning 7 0.12 29 Pesticide poisoning 61 1.06 30 Ulcerative colitis or Crohn’s disease 53 0.92 37 Head injury requiring medical attention 406 7.08 34 Injury from farm machinery requiring medical treatment (not including head injury)
566 9.88 33
* To preserve anonymity, where the number of respondents reporting a particular condition was less than 5, exact numbers of cases are not reported
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Lifetime prevalence greater than 10 % was reported for high blood pressure and work related musculoskeletal injuries. Health outcomes with a lifetime prevalence of less than 1 % included chronic obstructive pulmonary disease, emphysema, tuberculosis, Alzheimer’s disease, epilepsy, multiple sclerosis and chronic kidney infections.
3.3.1 Assessing the comparative health of the cohort
Comparing cohort health outcome prevalence to those observed in the general population provides a basis on which to draw some general conclusions about the general health of cohort members. In order to assess the comparative health of the cohort, an exercise was undertaken to compare the lifetime cohort prevalence for a number of chronic health outcomes with prevalence statistics for England published by the Health and Social Care Information Centrebb. Some additional prevalence comparisons (using data published in either peer reviewed journals or reputable ‘grey’ literature) were also made for asthma, chronic obstructive pulmonary disease (COPD), Alzheimer’s disease/dementia and Parkinson’s disease. Table 13 summarises the comparisons for the selected health outcomes. It is important to note that the data in Table 13 have not been adjusted for differences in for example the age and sex distribution of the cohort and that of the general population. Consequently any differences in the observed prevalence may be at least partially attributable to the lack of adjustment.
bb http://www.hscic.gov.uk/catalogue/PUB15751/qof-1314-report.pdf, Accessed 13/02/2015 16
Table 13 Comparisons of cohort lifetime prevalence rates of selcted long-term health outcomes with prevalence rates calculated by other research studies
Health outcome Cohort lifetime
prevalence (%)
Raw prevalence English GP practicescc
(%)
Estimated prevalence
– peer reviewed study (%)
Estimated prevalence –
voluntary sector
commissioned report (%)
Asthma 10.4 5.9 10.5 2
Chronic obstructive pulmonary disease (COPD)
0.98 1.8 1.403
Alzheimer's disease/Dementia
<0.09 0.6 1.14
Depression 6.0 6.5
Epilepsy 0.6 0.8
Parkinson’s disease
0.4 Not available 0.205
High blood pressure
14.8 13.7
Stroke 1.2 1.7
Diabetes 4.3 6.2
Rheumatoid arthritis
3.9 0.7
Chronic kidney disease
0.31 4.25
A mixed picture emerges with regard to respiratory conditions. The prevalence of COPD was lower among the cohort than the comparator populations, which may be explained by a lower than expected proportion of smokers. The cohort asthma prevalence is higher than that found in English GP practices, but has parity with the asthma prevalence for England estimated by Simpson et.al.(1)
With regard to neurological conditions the picture is again mixed. The cohort shows a markedly lower prevalence for Alzheimer’s disease/dementia, a similar prevalence for epilepsy and a higher prevalence for Parkinson’s disease when assessed against the comparator populations. At 0.4%, the cohort prevalence for Parkinson’s disease is twice that reported in the study carried out by the Parkinson’s UK research team(4). Other research 6 7 has reported a possible association between pesticide use and Parkinson’s disease; however, the elevated Parkinson’s prevalence in this cohort is not adjusted for age.
cc http://www.hscic.gov.uk/catalogue/PUB15751/qof-1314-report.pdf, Accessed 13/02/2015 17
Cohort prevalence for high blood pressure and stroke are broadly similar to prevalence in the comparator population, while the cohort prevalence for diabetes and chronic kidney disease are lower than that of the comparator population, with the prevalence of chronic kidney disease being lower by a factor of around 13. Conversely, the cohort prevalence for rheumatoid arthritis is higher than that for the comparator population by a factor of just over five.
Thus, in terms of health, the baseline cohort data present a mixed picture. As aspects of these variations may be age related (e.g. Parkinson’s disease, rheumatoid arthritis) further analysis of the data is preferred before more definitive conclusions are drawn.
3.3.2 Main areas of pesticide work, current and past
PIPAH study members report working in a wide range of work activities where they have been involved in applying pesticides. Figure 6 summarises the proportions of the PIPAH study group who report working in each of these activities.
In terms of current pesticide work, cereals, oilseeds and grassland/fodder crops involve the highest proportions of cohort members (approximately 60 %, 50 % and 40 % respectively as shown by Figure 6), all of which are practised in the agricultural sector. In addition, smaller proportions of the cohort report being involved in other areas of pesticide work such as forestry, soft fruit growing, and glasshouse crops. Cohort members were also asked about areas of pesticide activity that they have been involved with in the past, to provide an insight into changes over time in different areas of pesticide work. As with current pesticide use, use of pesticides in the past was concentrated in work with cereals, oilseeds, grassland/fodder crops and other arable crops. There is a notable reduction in the proportion of the cohort reporting involvement in potato related pesticide work.
Figure 6 Past and current areas of pesticide use
3.3.3 Time spent in different areas of pesticide work
A key proxy indicator of the potential level of pesticide exposure for study members is the overall time that they have worked in particular areas of pesticide work. Figure 7 summarises
MushroomsHopsAquaticHardy nursery stockOtherOutdoor ornamental flowers & bulbsSoft fruitGlasshouse cropsOrchard cropsForestryGolf courses, sports grounds, etcOutdoor vegetablesAmenity weed controlPotatoesSugar beetPoultry, livestock, animal housingPest controlOther arable cropsGrassland/fodder cropsOilseedsCereals
50 25 0 25 50 75 100Percentage of PIPAH study members
Past
Current
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the average number of years worked in different areas of pesticide work for cohort members. The areas of pesticide work with the highest average years worked (i.e. over 25 years) are cereals, grassland/fodder crops, pest control and poultry/livestock. Not unexpectedly, this finding mirrors the data summarising main areas of pesticide work. It follows, therefore, that cohort members with experience in these areas of work have potential for longer term exposure to pesticides.
Figure 7 Mean years spent in different areas of pesticide work
3.3.4 Types of pesticides used and the use of personal protective equipment (PPE)
Figure 8 shows that wood preservatives, herbicides, insecticides and fungicides were the most commonly used pesticides with over 90 % of the cohort reporting having used them. In contrast, cohort members reported a much lower use of fumigants and animal insecticides, with approximately one third of the cohort reporting their use.
For each of the pesticides asked about on the baseline questionnaire, cohort members were asked if they used personal protective equipment (PPE) when applying the product. Figure 8 also summarises the response patterns to these questions.
0 10 20 30Mean number of years
CerealsGrassland/fodder crops
Poultry,livestock,animal housingPest control
Other arable cropsSugar beet
Amenity weed controlOilseedsPotatoes
Orchard cropsForestry
Outdoor vegetablesOther
Hardy nursery stockGlasshouse crops
HopsSoft fruit
MushroomsAquatic
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Figure 8 Pesticide use and the use of PPE
A majority of study members who reported using plant growth regulators, fungicides, insecticides (including animal) and fumigants reported that they used PPE when applying these substances. In contrast, less than a fifth of the cohort reported using PPE when applying herbicides, and just under 50 % when handling treated seed. This finding suggests a potential for increased exposure risk for activities involving the use of herbicides and treated seed compared to other types of pesticide.
The relatively high proportion of missing data relating to the question about use of PPE with wood preservatives is noteworthy given that over 90% of cohort members report using this pesticide type and there were very few missing responses for the other pesticide types.
0 2,000 4,000 6,000Number of participants
Treated seed
Wood preservatives
Fumigants
Animal insecticides
Insecticides
Fungicides
Plant growth regulators
Herbicides
Used PPE Did not use PPE Response missing
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4. SUMMARY AND CONCLUSIONS
The overall response rate of around 20 % to the baseline General Questionnaire can be considered reasonable given the questionnaire’s length and relative complexity. Compared to the general population, the demographic profile of the PIPAH cohort indicates that a typical member is likely to be:
• older • male • married • a home owner/owner occupier • vocationally rather than academically qualified • self employed • a non-smoker and • a current drinker of alcohol
Some of these differences are to be expected given the occupationally specific nature of the pesticide applicator community. However, given the key aim of the study i.e. to investigate associations between health outcomes and exposure to pesticides, future statistical analysis will need to factor in relevant aspects of the cohort’s demographic profile. For example, if the prevalence of certain health outcomes has an age, sex and/or lifestyle related dimension, this will need to be considered in the data analysis process.
There is no evidence to suggest that the cohort is unrepresentative of the study sampling frame. For example, the descriptive statistical comparison of the sex distributions of the cohort and the study population suggests broadly comparable distributions. Unfortunately, there is limited data available to the researchers regarding other demographic characteristics of the study sampling frame. It is possible, therefore, that the cohort may be dissimilar when compared with respect to other demographic factors.
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5. REFERENCES
1. Fox D, Harding A-H, Frost G. The Prospective Investigation of Pesticide Applicators' Health Study: Background, Rationale and Design. HSE Research Report RR1103, 2017. Available from: http://www.hse.gov.uk/research/rrhtm/rr1115.htm
2. Simpson CR, Sheikh A. Trends in the epidemiology of asthma in England: a national study of 333,294 patients. Journal of the Royal Society of Medicine 2010;103:98-106.
3. Shahab L, Jarvis MJ, Britton J, et al. Prevalence, diagnosis and relation to tobacco dependence of chronic obstructive pulmonary disease in a nationally representative population sample. Thorax 2006;61:1043-47.
4. Albanese E, Banerjee S, Dhanasiri S, et al. Dememntia UK: the full report, 2007. 5. Parkinson's UK rt. Parkinson's prevalence in the United Kingdom (2009) 2012 [updated
2012. Available from: http://www.parkinsons.org.uk/sites/default/files/parkinsonsprevalenceuk_0.pdf accessed 10/21/2014 .
6. Priyadarshi A, Khuder S, Schaub E, et al. A meta-analysis of Parkinson's disease and exposure to pesticides. Neurotoxicology 2000;21(4):435-40.
7. Van Maele-Fabry G, Hoet PF, Vilain FF, et al. Occupational exposure to pesticides and Parkinson's disease: a systematic review and meta-analysis of cohort studies. Environment International 2012(1873-6750 (Electronic)):31-42.
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6. APPENDIX: PIPAH GENERAL QUESTIONNAIRE
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Published by the Health & Safety Executive 12/17
The Prospective Investigation of Pesticide Applicators’ Health (PIPAH) Study: baseline volunteer cohort
RR1119
www.hse.gov.uk
There are concerns that some pesticides may have levels of human toxicity that cause chronic health problems in workers who apply them, for instance cancers and neurological conditions. However, the evidence base linking worker exposure to pesticides and the development of adverse health outcomes is inconclusive. It is important to improve this evidence base so that any risks to worker health are understood and can be effectively controlled. The Prospective Investigation of Pesticide Applicators’ Health (PIPAH) Study is a long-term volunteer study established to develop a more complete understanding of how pesticide exposure potentially affects the health of workers. This report describes key features of the baseline cohort of 5,731 volunteers recruited to the PIPAH Study in 2013 to September 2014, the main recruitment period. The volunteers are workers who are professional and licensed GB pesticide users. The key features described are: demographics; health as compared to data on the general public from a large number of English General Practices; and ‘lifestyle’ data on diet, alcohol and smoking. PIPAH is a prospective cohort study: volunteers are recruited into the study, and factors that may be relevant to the development of disease will be measured over a number of years. The background to the PIPAH Study and its rationale and design are described in report RR1103. This report and the work it describes were funded by the Health and Safety Executive (HSE) and the Department for Environment, Food and Rural Affairs (DEFRA). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE or DEFRA policy.
