efectos potenciales a la salud por transgenicos y pesticidas

Potential Human Health Effects: Transgenics and Pesticides

Michael Hansen, Ph.D.

Senior Scientist

Consumers Union, US

Curso Bioseguridad

Florianópolis, Brazil

April 28, 2010

Outline

A. US FDA Policy on Genetically Engineered plants B. Bt crops--potential allergenicity and

immunogenicity concerns C. Unexpected Effects D. Do GE crops reduce pesticide use? E. Toxicity of glyphosate F. Conclusion

FDA Policy on Genetically Engineered Plants

Introduced at press conference at an industry gathering on May 27, 1992 by then Vice-President Dan Quayle as a deregulatory initiative

Based on notion “that the new techniques [e.g. genetic engineering] are extensions at the molecular level of traditional methods and will be used to achieve the same goals as traditional plant breeding” (57 FR 22991, May 29, 1992)

No requirement for human safety testing, only “voluntary safety consultations”; to date, some 80 voluntary safety consultations have been held

Key phrases in US Food and Drug Administration safety consultation letters

Letter for MON 810 (Bt corn), dated Sept. 26, 1996 “Monsanto submitted a summary assessment of corn containing

transformation event MON 810 on June 6, 1996” “Based on the safety and nutritional assessment you have

conducted, it is our understanding that Monsanto has concluded that corn products derived from this new variety are not materially different in composition, safety, and other relevant parameters from corn currently on the market, and that the genetically modified corn does not raise issues that would require premarket review or approval by FDA.” www.cfsan.fda.gov/~acrobat2/bnfL034.pdf

These two sentences found in all 80 safety consultation letters FDA does not require premarket safety assessment and does not state

its own opinion about the safety of the GE crop

Bt crops

Engineered with endotoxins produced by the soil bacterium Bacillus thuringiensis

Endotoxins are called Cry proteins and there are many of them

Bt crops on market include corn, potato, cotton, poplars; many are in testing phase, including Bt rice, Bt brinjal, Bt soy

Concern over allergenicity and immunological impacts on the gut

Joint FAO/WHO Expert Consultation on Allergenicity of Foods Derived from

Biotechnology, January, 2001

http://www.fao.org/es/ESN/food/risk_biotech_allergen_es.stm

Conclusions

2. The Consultation emphasized that all foods derived from biotechnology must be assessed for allergenic potential

Joint FAO/WHO Expert Consultation on Allergenicity of Foods Derived from Biotechnology,

January, 2001

7. The Consultation was of the opinion that an evaluation of proteins for sequence homology with sufficient sensitivity and specificity to detect potential cross-reactivity is an important part of the process for the assessment of the allergenicity of the expressed protein.


January, 2001 “6.1. Sequence Homology as Derived from Allergen Databases The commonly used protein databases (PIR, SwissProt and TrEMBL)

contain the amino acid sequence of most allergens for which this information is known. However, these databases are currently not fully up-to-date. A specialized allergen database is under construction.

Cross-reactivity between the expressed protein and a known allergen (as can be found in the protein databases) has to be considered where there is: 1) more than 35% identity in the amino acid sequence of the expressed protein (i.e. without the leader sequence, if any), using a window of 80 amino acids and a suitable gap penalty (using Clustal-type alignment programs or equivalent alignment programs) or: 2) identity of 6 contiguous amino acids.

If any of the identity scores equals or exceeds 35%, this is considered to indicate significant homology within the context of this assessment approach. The use of amino acid sequence homologies to identify prospective cross-reacting allergens in genetically-modified foods has been discussed in more detail elsewhere (Gendel, 1998a, Gendel, 1998b).


January, 2001

Recommendations:

1. The Consultation recommends that the FAO/WHO 2001 decision tree be used for determining allergenicity of foods derived from biotechnology

Kleter, G.A. and A.C.M Peijnenburg. 2002. Screening of transgenic proteins expressed in transgenic food crops for the

presence of short amino acid sequences identical to potential, IgE-binding linear epitopes of allergens. BMC Structural Biology, 2: 8.

www.biomedcentral.com/1472-6807/2/8

Compare transgenic protein from GE/GM crop with known allergen, looking for identical stretches of at least 6 amino acids

Screen positives further with: Epitope database Antigenicity prediction algorithm


presence of short amino acid sequences identical to potential, IgE-binding linear epitopes of allergens. BMC

Structural Biology, 2: 8.

Kleter, G.A. and A.C.M Peijnenburg. 2002. Screening of transgenic proteins expressed in transgenic food crops for the presence of short amino acid sequences

identical to potential, IgE-binding linear epitopes of allergens. BMC Structural Biology, 2: 8.

Kleter, G.A. and A.A.C.M Peijnenburg. 2002. Screening of transgenic proteins expressed in transgenic food crops for the


“Only a limited number of identical stretches shared by transgenic proteins (papaya ringspot virus coat protein, acetolactate synthase GH50, and glyphosate oxioreductase) and allergenic proteins could be identified as (part of) potential linear epitopes. . . The positive outcomes of this approach warrant further clinical testing for potential allergenicity.”

Gendel, S.M. 1998b. The use of amino acid sequence alignments to assess potential allergenicity of proteins used in genetically

modified foods. Advances in Food and Nutrition Research, 42: 44-61.

“although it is clear that some amino acid residues are critical for specific binding, some conservative substitutions may not affect allergenicity. Therefore, it may be prudent to treat sequence matches with a high degree of identity that occur within regions of similarity as significant even if the identity does not extend for eight or more amino acids. For example, the similarity between Cry1A(b) and vitellogenin might be sufficient to warrant additional evaluation” (Gendel, 1998b: 60).

Fares, NH & AK El-Sayed. 1998. Fine structural changes in the ileum of mice fed on delta-endotoxin-treated potatoes and transgenic potatoes. Natural

Toxins 6: 219-233.

Bt-potatoes and Bt-toxin (Cry 1) caused disruption, multinucleation, swelling, increased degradation of ileal (gut) surface cells in rats. Effect worse with Bt-toxin

These effects demonstrate that Bt-toxin survives digestion in functionally and immunologically active form

Fares, NH & AK El-Sayed. 1998. Fine structural changes in the ileum of mice fed on delta-endotoxin-treated potatoes and transgenic potatoes. Natural

Toxins 6: 219-233.

“These changes may suggest that delta-endotoxin-treated potatoes resulted in the development of hyperplastic cells in the mice ileum. Although mild changes are reported in the structural configuration of the ileum of mice fed on transgenic potatoes, nevertheless, thorough tests of these new types of genetically engineered crops must be made to avoid the risks before marketing.” (Fares and Sayed, 1998: 219)

Vazquez-Padron, R.I., Moreno-Fierros, L., Neri-Bazan, L., de la Riva, G.A. and R. Lopez-Revilla. 1999b. Bacillus thuringiensis

Cry1Ac protoxin is a potent systemic and mucosal adjuvant. Scandinavian Journal of Immunology 49: 578-584

“We conclude that Cry1Ac is a mucosal and systemic adjuvant as potent as CT [cholera toxin] which enhances mostly serum and intestinal IgG antibody responses” (Vazquez-Padron et al., 1999b: pg. 578).

Cry1Ac is potent stimulator of immune system

Cry1Ac survives digestion

Vazquez-Padron, R.I., et al. 2000b. Cry1Ac protoxin from Bacillus thuringiensis sp. kurstaki HD73 binds to surface proteins in the mouse small intestine. Biochemical and Biophysical Research

Communications 271, pp. 54-58

“we demonstrated that Cry1Ac protoxin (pCry1Ac) binds to the mucosal surface of the mouse small intestine . . . six pCry1Ac-binding polypeptides present in brush border membrane vesicles isolated from the small intestine. Moreover, this protein induced in situ temporal changes in the electrophysiological properties of the mouse jejunum. The data obtained indicate a possible interaction in vivo of Cry proteins with the animal bowel which could induce changes in the physiological status of the intestine” (Vazquez-Padron et al., 2000b: 54).

Vazquez-Padron, R.I., et al. 2000b. Cry1Ac protoxin from Bacillus thuringiensis sp. kurstaki HD73 binds to surface proteins in the mouse small intestine. Biochemical and Biophysical Research

Communications 271, pp. 54-58

“We think that previous to commercialization of food elaborated with self-insecticide transgenic plants it is necessary to perform toxicological tests to demonstrate the safety of Cry1A proteins for the mucosal tissue and for the immunological system of animals” (Vazquez-Padron et al., 2000b: 58).

Bernstein, et al. 1999. Immune responses in farm workers after exposure to Bacillus thuringiensis

pesticides. Environmental Health Perspectives, 107(7): 575-582

Scientists did study on farm workers in onion fields in Ohio, US that were exposed to Bt sprays

“reactivity [IgE antibodies] to the Btk pro-delta-endotoxin was encountered in 2 of 123 workers sensitized by the respiratory route . . . future clinical assessment of this possibility is now feasible because of the availability of reliable Bt skin and serologic reagents developed during the course of this investigation” (Bernstein et al., 1999: pg. 581).

Bernstein, et al. 2003. Clinical and laboratory investigation of allergy to genetically modified foods.

Environmental Health Perspectives, 111(8): 1114-1121.

“Workers in agricultural and food preparation facilities have potential inhalation exposure to plant dusts and flours. In 1999, researchers found that migrant health workers can become sensitized to certain Bt spore extracts after exposure to Bt spraying. Thus, the potential for occupational and consumer risks needs to be assessed.”

Impact of Bt cotton on farmers’ health (in Barwani and Dhar District of Madhya Pradesh) –Dr. Ashish Gupta et al.

Investigation Report Oct. – Dec. 2005www.gmwatch.org/print-archive2.asp?arcid=6265

Surveyed 5 villages, talked to people with symptoms and exposure to Bt cotton N = 23

All had skin symptoms, primarily itching (23), redness (19), or eruptions (20). The symptoms tended to occur on face (17), hands (15), feet (11)

Almost half (11) had eye symptoms—itching, redness and/or swelling

About 40% (9) had upper respiratory tract symptoms runny nose and/or excessive sneezing

Almost 90% had moderate (10) or severe symptoms (10)

Impact of Bt cotton on farmers’ health (in Barwani and Dhar District of Madhya Pradesh –Dr. Ashish Gupta et al.


Symptoms overwhelmingly on exposed parts of body (face, hand, feet, neck, eyes and respiratory tract). Only 1 of 23 had symptoms only on covered parts of body (14 exposed body parts only, 8 both)

Almost 80% (18) exposed in cotton field, 4 exposed at home Almost 74% (17) directly involved in picking cotton People that symptoms increased in severity when they continued to

work in fields and decreased when they stopped work Symptoms started within last two years, when Bt cotton was

introduced

Impact of Bt cotton on farmers’ health (in Barwani and Dhar District of Madhya Pradesh –Dr. Ashish Gupta et al.


Ginning factory Owner noted that “most of the farmers and labourers

were having skin related problems due to Bt cotton”

Detailed interview with 6 workers in different ginning factories found all had itching problems on exposed parts of body (hands, legs, face), and 2 were having eruptions on body

Workers had been in factory from 2 – 7 years, but symptoms only began last year, with introduction of Bt cotton

MON 863

MON 863—Monsanto Bt maize for corn rootworm (with Cry3Bb1)

Approved in US and in EU Monsanto submission revealed significant

effects on organs and blood parameters (Séralini et al. 2007. New analysis of a rat feeding study with a genetically modified maize reveals signs of hepatorenal toxicity. Arch Environ Contam Toxicol, 52: 596-602.)

Increased: basophils, lymphocytes and white blood cells. Decreased reticulocytes

Decreased kidney weight Increased blood sugar

Vendômois, JS, Roullier, F, Cellier, D and GE Séralini. 2009. A comparison of the effects of three GM corn varieties on

mammalian health. International Journal of Biological Sciences, 5(7): 706-726.

Study obtained Monsanto’s submission to EU for 3 GE corn varieties (NK 603, MON 810, MON 863) and reanalyzed all the data

“Approximately 60 different biochemical parameters were classified per organ and measured in serum and urine after 5 and 14 weeks of feeding.”

Vendômois, JS, Roullier, F, Cellier, D and GE Séralini. 2009. A comparison of the effects of three GM corn varieties on

mammalian health. International Journal of Biological Sciences, 5(7): 706-726.

“Our analysis clearly reveals for the 3 GMOs new side effects linked with GM maize consumption, which were sex- and often dose-dependent. Effects were mostly associated with the kidney and liver, the dietary detoxifying organs, although different between the 3 GMOs. Other effects were also noticed in the heart, adrenal glands, spleen and haematopoietic system. We conclude that these data highlight signs of hepatorenal toxicity, possibly due to the new pesticides specific to each GM corn. In addition, unintended direct and indirect metabolic consequences of the genetic modification cannot be excluded.”

Zolla, L. et al. 2008. Proteomics as a Complementary Tool for Identifying Unintended

Side Effects Occurring in Transgenic Maize Seeds As a Result of Genetic Modifications. Journal of

Proteome Research, 7: 1850-1861.

Proteomics is the study of expressed proteins. This is good way to detect unintended effects associated with GE, particularly the disruptive effects due to the random insertion of transgene

Superior study design: GE maize (MON810) and near isoline grown side-by-side in growth chamber, to control for environmental effects

Zolla, L. et al. 2008. Proteomics as a Complementary Tool for Identifying Unintended

Side Effects Occurring in Transgenic Maize Seeds As a Result of Genetic Modifications. Journal of

Proteome Research, 7: 1850-1861.

Results: “43 proteins resulted up- or down-regulated in transgenic seeds with respect to their controls (T06 vs WT06), which could be specifically related to the insertion of a single gene into a maize genome by particle bombardment.” (pg. 1850). Of these 43 proteins, 14 were down-regulated, 13 up-regulated, 9 shut off and 7 newly expressed.

“Interestingly, a newly expressed spot (SSP 6711) corresponding to 50 kDa gamma zein, a well-known allergenic protein, has been detected. Moreover, as a major concern, a number of seed storage proteins (such as globulins and vicilin-like embryo storage proteins) exhibited truncated forms having molecular masses significantly lower than the native ones.” (pg. 1855)

Finamore, A et al. 2008. Intestinal and Peripheral Immune Response to MON810 Maize

Ingestion in Weaning and Old Mice. Journal of Agricultural and Food Chemistry

Well designed study: MON810 and near isoline grown simultaneously in neighboring fields in Landriano, Italy, to control for environmental effects

“This study evaluated the gut and peripheral immune response to genetically modified (GM) maize in mice in vulnerable conditions. Weaning and old mice were fed a diet containing MON810 or its parental control maize . . . for 30 and 90 days. . . As compared to control maize, MON810 maize induced alterations in the percentage of T and B cells and of CD4+, CD8+, γδT, and RT subpopulations of weaning and old mice fed for 30 or 90 days, respectively, at the gut and peripheral sites. An increase of serum IL-6, IL-13, IL-12p70, and MIP-1 [cytokines involved in allergenic and inflammatory response] after MON810 feeding was also found. These results suggest the importance of the gut and peripheral immune response to GM crop ingestion as well as the age of the consumer in the GMO safety evaluation.”

Velirimov et al. 2008. Biological effects of transgenic maize NK603xMON810 fed in long term reproduction studies in

mice. Very carefully designed Austrian long-term feeding

study. The non-GE maize control was a near isogenic line. Both control and GE maize were grown in adjacent fields in Canada in the same year (2005, 2007), to control for environmental effects. Large sample sizes were used to detect more subtle adverse effects.

Major result: statistically significant adverse reproductive effects shown in the reproductive assessment by continuous breeding (RACB) study. RACB is a feeding study whereby a pair of mice are fed GM maize for 140 days, during which time the female is bred so that she delivers 4 litters. RACB puts mice under stress making it easier to detect adverse effects.

Velirimov et al. 2008. Biological effects of transgenic maize NK603xMON810 fed in long term reproduction studies in

mice.

“From 24 pairs assigned to the ISO and GM group, all females of the ISO group (100%) delivered 4 litters. In the GM group the number of deliveries declined with time. In the 4th litter only 20 deliveries occurred (p=0.055). The average number of pups born was always lower in the GM group but not significant before the 3rd delivery. There were significantly fewer pups born in the GM group in the 3rd (p= 0.011) and 4th (p=0.010) delivery and weaned in the 4th litter (p=0.025). Regarding all deliveries per group more pups were born in the ISO than in the GM group (1035 versus 844). Furthermore females of the GM group always had smaller litters (n < 8) as compared to females of the ISO group.”

Benbrook, C. 2004. Genetically engineered crops and pesticide use in the United States: The first nine years.

At: http://www.biotech-info.net/Full_version_first_nine.pdf

Benbrook, C. 2009. Genetically engineered crops and pesticide use in the United States:

The first thirteen years.

During first 9 years, pesticide use on genetically engineered crops was increased by a total of 122 million pounds.

Update on the Benbrook’s 2004 paper: “Bt corn and cotton has reduced insecticide use by 56 million pounds, but herbicide tolerant crops have increased pesticide use by 383 million pounds, for an overall 327 million pounds increase over the 13 years.”

So, for 1996-2004, 122 million pounds more pesticide was used on GE compared to non-GE crops. For 2005-2008, an additional 205 million extra pounds were applied.

Wang, S., Just, D.R. and P. Pinstrup-Andersen. Tarnishing Silver Bullets: Bt technology adoption, bounded rationality and the outbreak

of secondary pest infestations in China. Paper presented at American Ag. Econ. Assoc. annual meeting, Long Beach,

CA, 22-26 July, 2006

Household survey of 481 farmers, 20 villages, 5 provinces: Hebei, Shandong, Henan, Anhui, Hubei

Results for 2004: Average expenditure on pesticides was same ( US$101/ha)

between Bt and non-BT farmers Bt farmers spend 46% less on bollworm pesticide, but spend 40%

more on pesticides for secondary pest(s), compared to non-Bt farmers

Main secondary pest – mirids GM cotton seeds cost 3 times more than non-Bt cotton, so Bt

farmers make less money than non-Bt farmers Results markedly different from data from 1999, 2000, 2001



CA, 22-26 July, 2006

Wang, S., Just, D.R. and P. Pinstrup-Andersen. Tarnishing Silver Bullets: Bt technology adoption, bounded rationality and the outbreak of

secondary pest infestations in China. Paper presented at American Ag. Econ. Assoc. annual meeting,

Long Beach, CA, 22-26 July, 2006



CA, 22-26 July, 2006

Do GE crops reduce pesticide use?

“farmers have rotated RR crops, usually soya and maize, to the point that the weeds themselves are now Roundup resistant, which has resulted in much higher applications of Roundup along with a host of other chemicals.” Nathalie Moll, EuropaBio. In “GM crops: Biotech agriculture—Time to take GM seriously”, Ethical Corporation, February 7, 2008 At: www.ethicalcorp.com/content.asp?ContentID=5684

Richard, S. et al. 2005. Differential effects of glyphosate and Roundup on human placental cells and aromatase. Environmental Health

Perspectives, 113(6): 716-720.

Exposure of male farmers in Ontario, Canada to glyphosate-based herbicides was associated with increase in miscarriage and premature birth in farm families (Savitz et al. 1997. Male pesticide exposure and pregnancy outcome. Am

J Epidemiology, 146: 1025-1036.) this study tried to look at possible mechanisms.

Design: incubated human placental JEG3 cells with various concentrations of Roundup (up to 2%) or equivalent concentrations of glyphosate. Cell viability was measured after 18, 24, and 48 hours. Aromatase (which regulates estrogen synthesis) levels were measured after 1 hour and 18 hours.

Results: 2% Roundup and an equivalent concentration of glyphosate killed 90% of the JEG3 cells after 18 hours incubation. Median lethal dose for Roundup (0.7%) was approximately 1.8 times lower than for glyphosate. Viability of cells exposed to glyphosate was considerably reduced when just 0.1% Roundup was added.

Richard, S. et al. 2005. Differential effects of glyphosate and Roundup on human placental cells and aromatase. Environmental Health

Perspectives, 113(6): 716-720. Cont’d

Results: After 1 hour incubation with Roundup, aromatase activity increased by 40%. After 18 hours, synthesis was inhibited, with a median inhibiting concentration (IC50) of 0.04%, perhaps reflecting an effect on aromatase gene expression. No effect was seen with glyphosate alone.

In sum, study showed that effect of Roundup on cell viability increased with time and was obtained with concentrations of Roundup 10 times lower than those recommended for agricultural use. Roundup also disrupted aromatase activity at concentrations 100 times lower than those used in agriculture.

Eriksson, S., Hardell, L et al. 2008. Pesticide exposure as risk factor for non-Hodgkin lymphoma including histopathological subgroup analysis.

Int. J. of Cancer, 123: 1657-1663.

Design: Population based case-control study. 910 NHL cases (male and female age 18-74 years, living in Sweden, from December 1, 1999, to April 30, 2002) and 1016 controls.

Results: Exposure to phenoxyacetic acids yielded odds ration (OR) 2.04 (95% confidence interval [CI 1.18-2.51]). Exposure to glyphosate gave OR of 2.02, 95% CI 1.10-3.71 and with >10 years latency period OR was 2.26, 95% CI 1.16-4.40.

Previous study involving pooled analysis of 2 Swedish case-control studies showed OR for glyphosate of 3.04 (95% CI 1.08-8.52). (Hardell, L., Eriksson, M and M. Nordstrom. 2002. Exposure to pesticides as risk factor for non-Hodgkin’s lymphoma and hairy cell leukemia: pooled analysis of two Swedish case-control studies. Leukemia Lympoma, 1043-

1049) Conclusion: “our study confirmed an association between exposure to

phenoxyacetic acids and NHL and the association with glyphosate was considerably strengthened.”

Conclusion

1. US FDA does not require preapproval safety assessments

2. The endotoxins in Bt crops raise issues of allergenicity andimmunogenicity

3. Feeding studies have found unexpected adverse effects

4. Between 1995-2009, GE crops in US have increased use of herbicides, particularly glyphosate, by 383 million

pounds and decreased insecticide use by 56 million pounds

5. Roundup appears to be an endocrine disruptor and has been linked to increased risk of Non-Hodgkin’s lymphoma

efectos potenciales a la salud por transgenicos y pesticidas

Health & Medicine

allergenicity of foods

bt corn

modified foods

premarket safety assessment

bt crops

sequence homology

human safety testing

voluntary safety consultations