Response from the Authors of the 'Ontario report'.
Following its September 2004 meeting, the Advisory Committee on Pesticides (ACP) published a statement on the Pesticides Literature Review compiled by the Ontario College of Family Physicians. At the same time, as agreed at the September 2004 meeting, we wrote to the authors of the Ontario report inviting them to respond to our criticisms of their work. Their response, which is set out below, was discussed by the ACP at its meeting on 18 November. We appreciate the willingness of the authors to engage in discussion of their work in this way, and we sympathise with the constraints under which they were working, particularly in terms of resource.
Having considered the response, the majority of ACP members, including all members appointed because of their expertise in epidemiology and toxicology, remain of the view that the report does not raise concerns about pesticide safety that were not already being addressed, and does not indicate any need for additional regulatory action in the UK.
Response to: Chairman of the UK Government’s Advisory Committee on Pesticides (ACP) ACP12/1 (307/2004) Chairman’s statement and the tabular summary of ACP8 (309/2004) re the “Ontario review” (received 30 September, 2004)
From: (Ontario College of Family Physicians (OCFP)) review team
Date: 5 October 2004 (given deadline of 7 October, 2004 for ACP comments to appear on the website and our desire to have our response also posted)
Dear colleagues:
Thank you very much for the opportunity to respond to your comments on the OCFP review. We appreciate that our review may have been presented in a lay format less conducive to formal critiques by scientific colleagues. It would have been helpful to know of your interest earlier so that we might have supplemented the information available and indicated the rationale behind some of the difficult scoping choices that we had to make. For example, we limited the time period of our primary reviews to post 1992 and relied on other published reviews for reference to studies earlier than that. In this, our structure and resources may be different from yours.
Reviewers were a mix of family physicians with considerable clinical experience and graduate students with limited experience in epidemiology and two of us with more extensive training and experience i.e. no toxicologists and hence our lack of review of that literature (table criticism 7, Chairman’s comment 9). We had a relatively small budget (about $CDN 40,000) over a relatively brief time period (just over one year) on a part-time basis to cover a wide set of review questions that might be posed in more refined terms of specific pesticide groups (table criticism 6) and specific health outcomes (table criticism 5) if more resources were available. As a government funded multi-disciplinary group committee, you would appear to have both cumulative experience and resources over many years as well as the ability to commission focused reviews as required. Hence, your set of committees are likely more able to look at the entire relevant literature without restriction on date (table criticism 1) or discipline (table criticism 7) and thus more completely identify all relevant studies (Chairman’s statement, point 2; table criticism 3). We regret the omissions that you note (Chairman’s statement, point 6) which would have added important information to our review. We were glad to see that you also felt that the genotoxicity biomarkers literature warranted a more detailed examination (Chairman’s statement, point 2).
However, we would disagree that we did not “take proper account of all or even most of the available scientific evidence” (Chairman’s statement, point 4) given that we did identify the majority of relevant human epidemiological and biomarker studies relevant to chronic effects. We limited our review to chronic rather than acute effects (Chairman’s comment 11), as this was the set of effects about which family physicians felt less certain and upon which they had received challenges. You call for a clearer articulation of the exact search strategy and criteria for selection of papers than we were able to provide in the brief overall methods chapter (table criticism 2; Chairman’s statement, point 7). In retrospect, we would agree that a more detailed appendix that could be separate from the overall report but been available on the web site might have better represented the process that we followed. We noted the potential for bias associated with computerized searches (Chairman’s statement, point 7) in the sources of bias section of our methods chapter and, with our limited resources, were unable to cast the net wider other than by asking experts in the field known to members of the review team to check on the completeness of our searches.
A number of the tabled criticisms (6, 7, 9 & 10) and the Chairman’s statements (8 & 9) demonstrate interest in more detailed discussions of the studies included in the review. Certainly when the focus is only one of the associations of one particular pesticide group with a particular health outcome and considerable resources are available, as would appear to have been the case for chronic toxicity of organophosphates for your COT report, more detailed discussion is highly desirable. However, we were more interested in a broad map of the literature, which might spur on more focused systematic reviews or additional primary research (as per our recommendation). We were also struck by a number of features of the literature that we commented upon in our methods and particular health outcome chapters, including: 1) the mixed nature of pesticide exposures for most human populations, making relationships with particular pesticides difficult to disentangle (table criticism 6); 2) the relative lack of information on routes and even intensities of exposure, making comments on such variation difficult (table criticism 8); 3) the limited number of studies on children, a primary interest of the public, the review group, and our funder; and 4) the dearth of intervention evaluation studies, which could greatly assist in providing more appropriate management guidance (Chairman’s comment 12).
Your Chairman notes a number of statements that he regarded as “superficial”, “naïve”, “simplistic”, “misleading” and “unconventional” (Chairman’s statement 3, 8, 9, & 10). Some appear to be based on selective citation. Space and language limitations associated with such professional and lay reports also severely limit the ability to make more extensive and fulsome explanations. However, we appreciate his detailed noting of inconsistencies that indicate the need for additional editorial work than our available human resources permitted at the time.
Your criticism that our conclusions were unhelpful (table criticism 11, Chairman’s statement 12) may partly relate to the audiences to which you usually speak versus primary care physicians and the lay public which we chose for this report. Reductions in use and exposure are within the scope of much of the public, and hence was the focus of this report. Diagnostic approaches were not the focus of the report though both our own work in the Canadian Medical Association Journal and that of others, particularly from the well-funded US sources, are used in our workshops for family physicians on diagnosis and management.
Overall, we were saddened by the overwhelming negative tone of your criticisms. We can always demand better reviews and better evidence, but we should ask ourselves whether this is the best way to move policy and practice towards more sustainable approaches to human activity in the long term. We trust you will be respectful and include these comments on your web site, in addition to your own comments.