Science in Society Archive

More Illnesses Linked to Bt Crops

Further evidence has emerged on the link between common transgenic proteins and serious allergic reactions while regulators turn a deaf ear and approve yet more planting. Dr. Mae-Wan Ho

The same transgenic proteins implicated in two different GM crops

We recently reported illnesses and deaths among villagers of south Mindanao in the Philippines that are suspected of being linked to the genetically modified ‘Bt’ maize with an insecticidal protein from the soil bacterium Bacillus thuringiensis  [1] (“GM ban long overdue, five deaths and dozens ill in the Philippines”, SiS 29).

Since then, similar illnesses are reported to have occurred in Madhya Pradesh, central India, as a result of exposure to ‘Bt’ cotton genetically modified with the same or similar insecticidal protein(s).

India began commercial planting of Bt cotton in 2002/03 with 38 038 ha (0.78 percent of hybrid area), increasing to 6.4 percent and 11.65 percent respectively in 2003/4 and 2004/5. Currently, nearly 9 million ha of cotton is grown in India, 2.8 million hybrid cotton.

Madhya Pradesh is India’s fifth largest cotton producing state, with Malwa and Nimad the main cotton growing regions. The Bt cotton varieties planted were developed by Monsanto, and carry the insecticidal Cry1Ac protein (Bollgard) or both Cry1Ac and Cry1Ab proteins (Bollgard II), according to an article on the industry’s website [2].

Farmers from the Nimad region in Western Madhya Pradesh began complaining of health hazards after Bt cotton was planted. This prompted a three-member team representing a coalition of non-government organisations to carry out a preliminary survey in six villages in Nimad region between October and December 2005.

Similar symptoms

The team interviewed 23 of the farm and factory workers who fell ill after having handled Bt cotton. All had itching skin, 20 had eruptions on the body, and 13 had swollen faces.  In some cases, the itching was so bad that they had to discontinue work, or take anti-allergy medicine in order to be able to work.

The survey resulted in a report which concluded [3]: “All the evidence gathered during the investigation shows that Bt has been causing skin, upper respiratory tract and eye allergy among persons exposed to cotton... The allergy is not restricted to farm labourers involved in picking cotton but has affected labourers involved in loading and unloading Bt from villages to market, those involved in its weighing, labourers working in ginning factories, people who carried out other operations in the field of Bt cotton, or farmers who stored cotton in their homes etc.”

The team consisted of Dr. Ashish Gupta of Jan Swasthya Abhiyan (People’s Health Movement, India); Ashish Mandloi, a graduate of Barwani College working with Narmada Bachao Anolan (Save Narmada River Movement) and associate of the National Alliance of Peoples’ Movements; and Amulya Nidhi, a health activist working in Maharastra and Madhya Pradesh specializing in Urban and Rural community Development, and associated with Shilpi Trust and Jan Swasthya Abhiyan.

The survey covered 6 villages in the Barwani and Dhar districts of Nimad region in Madhya Pradesh, interviewing various groups of people involved in handling cotton - women picking cotton, labourers loading-unloading cotton, ginning factory workers - as well as a local doctor and an agricultural scientist.

Allergy symptoms in farm workers and other workers handling Bt cotton

The team found allergy symptoms in people in direct contact with Bt cotton on their hands, feet, face, in their eyes and nose, with some becoming “very severely ill.”

The skin was the most common site of allergy: itching, redness, eruptions and swelling. Typically, after the first 4-5 hours of exposure, most people complained of itching on the face and the hand. Soon, the itching increased and by the time they finish the day’s work, they had redness on the hands and face and swelling of the face. After continued exposure of one to two days, small white eruptions would appear, most often on the face. The symptoms began to subside after varying periods from four to five days up to five to six months, but black discolouration would show on the skin.

The people affected did not have previous history of allergies even though they were involved in picking cotton earlier.

Those who had more severe symptoms of the skin tend also to have associated allergies of eyes and respiratory tract. Eye irritation, involving itching, redness, swelling and watery eyes affected 11 of the 23 individuals; 9 had upper respiratory symptoms of watering from the nose and excessive sneezing. Three had mild symptoms, while 10 each had severe and moderate symptoms respectively.

One woman had to be removed from the fields and taken to Barwani District Hospital where she remained for 9 days.

Cotton fibre appeared to be causing the allergy. (In the case of the Bt maize in the Philippines, the pollen was suspected to be the main culprit.) The owner of the ginning factory Mr. Sunil Patidar said that symptoms like itching, redness of eyes, watering of eyes and cough were found in labourers in his factory. Most of the labourers were having problems, and the year before, it was even more prevalent. He said that was why labourers were not ready to unload the cotton-loaded truck from Maharastra.

The labourers working in different ginning factories said itching of the whole body was very common, and only when they took Tab. Avil (a common anti-allergy medicine) every day were they able to work.

Kalibai of Kothra said she has been working for 20 years picking cotton and never had any symptoms until 2004, when she suffered very bad allergy from picking Bt cotton.

Dr. Ramesh Jar of Saigaon, Ayurvedic doctor, has been practicing in Aawli, Tal Thikri in District Barwani. He said he has already received around 150 cases of allergy from two villages of Aawli and Saigaon in 2005. In 2004, he had around 100 cases. He is prescribing Dexona injection and Levocetrigen for skin and anti allergic drops for eyes.

Dr. Debashish Baner, an agricultural scientist, thinks that Bt cotton produces Bt toxin in all tissues including cotton fibres.

The team is demanding a government enquiry; but that seems to have fallen on deaf ears so far.

Bt bacteria and spores were previously linked to allergic reactions

Bt toxins come from the soil bacterium Bacilllus thuringiensis (Bt), common strains of which produce a large family of insecticide Cry proteins each targeting a different range of insect pests. Strains of Bt have been used as sprays to control insect pests in the United States for many years before transgenic Bt crops were created.

A study published in 1999 funded by the US Environment Protection Agency found that exposure to the Bt sprays “may lead to allergic skin sensitisation and induction of IgE and IgG antibodies or both” [5].

Farm workers who picked vegetables that required Bt spraying were evaluated before and after exposure to Bt spray, and one and four months afterwards. Two groups of low, and medium exposure workers not directly exposed to Bt spray, but working at different distances from the sprayed fields were also assessed. Investigations included questionnaires, nasal/mouth lavages, assessment of ventilatory function, and skin tests. To authenticate exposure to the organism present in the commercial preparation, bacteria isolated from lavage specimens were tested for Bt genes by DNA-DNA hybridisation. Blood immunoglobulin G and IgE responses to spore and vegetative Bt extracts were assayed.

Positive skin-prick tests to several spore extracts were seen chiefly in exposed workers. In particular, there was a significant increase in the number of positive skin tests to spore extracts one and four months after exposure to Bt spray. The number of positive skin test responses was also significantly greater in high- than in low- or medium-exposure group of workers. The majority of nasal lavage cultures from exposed workers was positive for the commercial Bt organism as demonstrated by specific molecular genetic probes. Specific IgE antibodies were present in more workers from the high-exposure group than from low- and medium-exposure groups. Specific IgG antibodies also occurred more frequently in the high- than in the low-exposure group.

In a previous public health survey of a large number of individuals exposed to a massive Bt pesticide spraying programme [6], some of the symptoms recorded include rash and deep swelling. One worker developed inflammation of the skin, itching, swelling and reddening of the skin with redness of the eyes. Bt was cultured from the red eyes.

In 1992, Bt was used in an Asian gypsy moth control programme, and was found to be associated with classical allergic rhinitis (inflammation of the nasal mucosa) symptoms, exacerbations of asthma, and skin reactions among exposed individuals reporting possible health effects after the spraying operations [7]. Similar findings occurred during another Bt spraying in the spring of 1994 [8].

Allergens trigger 75 percent of asthma cases

Allergenicity is of particular concern because approximately 75 percent of asthma cases are triggered by allergens [9] and illnesses and deaths due to asthma have rocketed in recent years. Asthma deaths tripled in the United States from 1 674 in 1977 to 5 438 in 1998. The costs of asthma doubled from $6.2 billion in 1990 to $12.7 billion in 2000 [10].

Bt crops were first introduced in the United States in 1996, and have expanded substantially in acreage since, with little or no further research on the toxicity or allergenicity of the Cry proteins released in greater and greater abundance into the environment. Limited studies carried out by a research team in Cuba showed that Cry1Ac is a powerful immunogen, and when fed to mice, induced antibody responses similar to those obtained with the cholera toxin. Furthermore, Cry1Ac actively binds to the inner surface of the mouse small intestine, especially to the ‘brush border’ membranes on the cells lining the small intestine [11].

It has also been shown that all the Cry proteins in Bt crops have amino acid sequence similarities to known allergens [12-14], and are hence potential allergens.

Regulators are guilty of gross negligence

Meanwhile, the biotech industry has been aggressively promoting GM crops worldwide, especially those with Bt biopesticide and in developing countries like India and the Philippines. The latest survey carried out by the industry-funded group ISAAA claims that the global area given over to GM crops has increased from 81 million ha in 2004 to 90 million ha in 2005 [15]. Bt crops now comprise 29 percent of the total (18 percent Bt, and 11 percent stacked Bt and herbicide tolerance).

Regulators continue to approve Bt crops, despite the fact that successive surveys carried out both by scientists and by non-government organisations have demonstrated that Bt crops have failed to match the performance of local varieties [16] and farmers who bought into the aggressive propaganda have ended up in debt, and worse, suicide [17-18], so much so that an “agrarian crisis” was declared in Maharastra.

The latest evidence of serious health impacts linked to Bt crops comes in corroboration of previous findings dating back to the 1980s that should have halted the development and approval of Bt crops then.

By now, it is simply gross negligence not to impose a ban on further releases of Bt crops until they have been proven safe by a thoroughly independent enquiry.

Article first published 18/04/06


  1. Ho MW. GM ban long overdue, dozens ill & five deaths in the Philippines. Science in Society 2006, 29, 26-27,
  2. Manjunath TM. Safety of Bt-cotton: facts allay fear. AgBioWorld, 2005,
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  12. Kleter GA and Peijnenburg Ad ACM. 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 2002, 2:8
  13. Fiers MWEJ, Kleter GA, Nijland H, Peijnenburg Ad ACM, Nap JP and van Ham R CHJ. Allermatch TM, a webtool for the prediction of potential allergenicity according to current FAO/WHO Codex alimentarius guidelines. BMC Bioinformatics 2004, 5:133
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  15. Clive James, Global Status of Commercialized Biotech/GM Crops: 2005. ISAAA 10 Jan. 2006,
  16. Ho MW. Scientists confirm failures of Bt-crops. Science in Society 2006, 28, 22-24,
  17. Gala R. Indian cotton farmers betrayed. Science in Society 2006, 29, 35-37,
  18.  “Monsanto’s Bt cotton has failed in India: gene campaign”, Suman Sahai and Veena Pachhapur,
  19. “Vidharbha agrarian crisis worsen as 33 farmers commit suicide in last 10 days taking total toll to 405. Farmers are innocent victims of govt. policies”, Kishor Tiwari, Vidarbha Jan Andolan Samiti, 28 March 2006, Press Notice,

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