Report to Ministry of Health, New Zealand Concerning the Potential Health Impacts of Foray 48B Application 

Summary

The purpose of this report was to identify what the NZ government should do, if anything, to make sure that spraying Foray 48B on large numbers of people would be safe. The government commisioned researches at the Wellington School of Medicine, the University of Auckland, and other researchers in public health to receive and analyze reports of ill effects from the sprayed communities, and also to "...review existing scientific knowledge relevant to these health concerns, symptoms and effects, and recommend (but not carry out) scientifically robust methods of further study." The report was submitted for final review to the health ministry sometime in the summer of 2003. The government refused to release any information to the public or press about what was in the report. The researchers were not happy with this, according to statements in the NZ press. Finally, almost a year later (late spring 2004) the report has been quietly made available.

The report includes results of an uncontrolled study using focus groups to determine people's perceived and actual state of health before and after sprayings. The researchers also did an extensive literature survey and summarized their understanding of the safety of the active ingredient Btk (they did not attempt to discuss, except in passing, any effects from inert ingredients).

The executive summary contains the major conclusions reached in the report:

But beyond the executive summary, it is quite revealing to read the literature survey and summaries in the report. No Spray Zone has received a draft copy of the report which includes comments by a peer reviewer (in italics) and the responses to those comments in red.  Here are a few interesting excerpts with NSZ's comments in green. (NB: we make every attempt to quote enough so that remarks are not taken out of context):
 
Bt products have been used as insecticides since the 1950s. Bt is closely related to Bacillus cereus, a bacterium which is known to cause food poisoning. [You haven’t pointed out that Bt is closely related to B anthracis, cause of anthrax and a bioterrorism weapon [ (;->) ]OK ... Because normal clinical practice does not distinguish between Bacillus cereus and Bacillus thuringiensis, the relative contribution of these Bacillus species to human disease is unknown. Foray 48B contains a particular subspecies called Bacillus thuringiensis kurstaki (Btk). [This paragraph is quite misleading, as it could be read to imply that Bt could be widely causing food poisoning, without it being distinguished from B cereus, of which there is little (or no) evidence in our view, that would be a reasonable conclusion.....We were informed by the manufacturer that manufacturing standards for Bt-based insecticides from the USEPA require assays of enterotoxin and have quite tight controls. The fact that enterotoxin is not present in the product when sprayed does not preclude the possibility of enterotoxin being produced during subsequent growth in the environment - or people… see: (Jensen et al. 2002a; Jensen et al. 2002b;Hendriksen and Hansen 2002) ] The authors are making the point that there is reasonable possibility that Btk has inherent enterotoxic (that is, can cause gastroenteritis and other problems in the gut) activity when growing. Such a possibility is supported by many research papers. Also note that they seem to believe that Btk does grow in humans.

You have failed to note that the largest population-based surveillance studies have covered tens of thousands of people. Population-based surveillance has covered large populations (as noted in the main text). This provides limited reassurance that exposure to Bt probably does not cause a dramatic increase in serious disease. It is not good evidence of overall safety. This exactly echoes our statements that no adequate population studies have been done that reasonably assure the safety of Btk-based sprays.

In relation to the biological components of Bt, one other relevant study has recently been published. Hendriksen and Hansen (2002) reported that Bt:
“… survives as spores for long periods in bulk soil, a relatively protected environment… survival of Bt is a more dynamic process than previously thought, involving germination, possible cell divisions, and sporulation. These observations may have major implications for the understanding of the ecology of Bt in the environment, for its use as a microbial pest control agent, and the associated risk assessments.” (Hendriksen and Hansen 2002) Another indication that maybe we don't know enough yet to be using Btk-based sprays for larg-scale spraying programs with confidence as to their environmental safety.

Since clinical tests do not normally distinguish B. thuringiensis from the closely related pathogen, B. cereus (WHO, 1999), the significance of B. thuringiensis as a cause of human disease is not known. [This statement is open to some misinterpretation so needs clarifying. It could equally be read as “ significance unknown, but likely to be a common and serious pathogen” or “ significance unknown, but unlikely to be a common and serious pathogen” . The weight of evidence seems to lie with the latter. Not clear what evidence is referred to here. The point is that B. thuringiensis is not usually distinguished from B. cereus...

Foray 48B used in New Zealand is said to be tested for the presence of unwanted toxins (Kalemba et al. 2002). However, it is not clear how sensitive or reliable these tests are, since there are no widely accepted test protocols for organisms . Bacteria can also produce a range of toxins during growth. If bacteria from Foray 48B grow after release, this could result in human exposure to toxins even if no toxins were present in the original product.
[The F48B product has to meet EPA manufacturing quality control standards which includes various toxin assays and rejection criteria for batches. This should be quite detailed, and according to Ian Gear at MAF, (who visited the plant recently) similar to FDA criteria for cultures used in Abbott Laboratories’[Foray 48B is produced by Valent Bioscience, not part of Abbott] drug manufacture. The criteria may include post-manufacture culture, but you’d have to confirm this. MAF has batch-tested each shipment arriving here looking for non-Btk contaminants, but you’d have to confirm with them what is done. US EPA set and monitor the criteria, so if you want to review the validity of their method would need some rigorous research information. The final sentence needs to be backed up with evidence otherwise it is open to various interpretations.–OK, will add a reference [For example, see the citations above. We believe the authors already answered this point.] To what extent does expression of toxins in the environment which aren’ t produced during culture/manufacture actually happen? To what extent is the genome of the F48B Btk strain capable of producing other toxins? (the genetic research on this strain is quite extensive, but totally unintelligible to me)The genetic coding of toxins is carried by plasmids which are readily exchanged between species (including other species present in the environment)

...It is well established that fine particles (PM10 and finer) cause cardiorespiratory diseases and increased daily mortality in exposed communities. It is not clear which features of respirable particles are responsible for these effects, but there is evidence that bacterial toxins may be involved (WHO 2003).
[The section on bioaerosols is useful and worth exploring further. My reading, from your references and a few other papers, is that many of the effects are highly substance-specific (microbiological and/or physico-chemical), rather than generic effects. That is probably true of some effects, but not all. Specific research would be needed on Btk products such as F48B to attempt to get some clarification and quantification. We agree that this would be helpful, but not necessary before reaching our conclusions. Which of the listed symptoms are generic? The irritant effects seem non-specific to bacterial cell wall components. We’ ve thought about the irritant symptoms as being possibly related to pH, hypertonicity, or particular organic acids in the product. That is possible, but fails to explain the specificity of the symptoms. Much of the upper airway and mucosal symptoms are likely to be from larger particles, rather than PM10 size, but what implications does this have for assessing effect? Presumably, effects on respiratory disease are more likely if respirable particles are inhaled...

More speculatively, there is also the theoretical potential for other human diseases triggered by biologically active chemicals produced during growth of Bt. In toxicology experiments using human cell cultures, growth of Bt has been shown to have a variety of effects, including cell damage and immunological effects. The public health significance of these findings is unclear.
[See previous comments on speculation – recommend re-wording based on weight of evidence] “ The public health significance of these findings is unclear.” Should we remove the whole paragraph in order to avoid misinterpretation? We disagree


 
 
 
 
 
 
 
 

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