GENTECH archive


Re: Bt pesticides, archive 2302

Dear Rick
Putting Bt in food does not necessarily compensate by sparing farmers the Bt spray.  If Bt is expressed in the food it may be simply taking the problem from the farmers and putting it on the consuming public.  Yeah, great thinking Rick.  I don't think this is good science.   I shall continue to look for more studies before I make an informed comment and you can look forward to further comment then.
Only long term human feeding studies are acceptable as risk assessment.  In the meantime I support a moratorium on Bt crops as a safeguard for both the environment and human health - what happened to the precautionary principle......
For the record, I don't support the use of Bt in organic farming.
-----Original Message-----
From: Rick Roush <>
To: Dorothy Bowes <>
Cc: <>
Date: Tuesday, 7 December 1999 17:57
Subject: Re: Bt pesticides, archive 2302


Another (minor) reason to use Bt crops that produce only one Bt protein rather than continue to expose farm workers to a Bt spray in which there are thousands of bacterial proteins, some of which are bound to have allergenic potential.


Dorothy's message:
Health risks of Bt pesticide

Claims of health risks to Bt pesticides have been minimal, but this may be due to lack of health data as the potential allergenicity of these organisms has not been evaluated. To address the lack of data a health survey was conducted in farm workers before and after exposure to Bt pesticides. The workers were evaluated before the spraying and one and four months after the spraying. Two groups of low and medium exposure workers were also assessed. While there was no evidence of occupationally related respiratory disease, positive skin prick tests were seen in exposed workers with a significant increase in the number of positive tests to spores 1 to 4 months after exposure to Bt spray. The increase was more significant in high rather than low exposure workers. The study concluded that exposure to Bt sprays may lead to allergic skin sensitisation and induction of IgE antibodies or IgG antibodies - or both.

- Bernstein J L et al. 1999. Immune responses in farm workers after exposure to Bacillus thuringiensis pesticides. Environmental Health Perspectives. 107 (7): 575-582.