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PROBLEMS WITH MICROCHIP IMPLANTATION: AND WHY THEY MATTER

Since their introduction in the late 1980s, implantable microchips have become the industry standard for identifying mice and rats used in laboratory research. Animal shelters and veterinarians now routinely inject microchips into dogs and cats. More recently, there has been a push to implant microchips into people for security and building access, to manage medical records, and to identify elderly patients.

American workers at the now-defunct CityWatcher surveillance company (VeriChip Corp., 2006) and officials with the Mexican Attorney General’s office (Applied Digital Solutions, 2004) have been microchipped. Concern that the practice could spread has raised the specter of Big Brother and prompted lawmakers in three states to pass laws preventing the forced or coerced implantation of microchips in human beings. California, Wisconsin, and North Dakota have all passed laws banning forced or coerced microchip implantation in human beings. See: California SB 362 (2007), Wisconsin AB 290 (2005), and North Dakota SB 2415 (2007).

There is now an ongoing debate regarding the safety of the chips. As a result of lobby pressure combined with heavy advertising by Schering Plough for its HomeAgain pet recovery system, close to 5% of the United States’ estimated 164 million dogs and cats have now been chipped (Banfield the Pet Hospital, 2005). Animal shelters around the United States are routinely chipping dogs and cats before releasing them for adoption, and governments, including those of Portugal, Singapore, Bangkok, Los Angeles County, and El Paso, Texas, have passed ordinances requiring that all dogs under their jurisdiction be microchipped. El Paso has extended the chipping mandate to cats and ferrets.

In addition, horses around the nation are also being chipped, and the USDA recently approved the use of equine radio-frequency identification (RFID) injectable transponders as part of the National Animal Identification System (NAIS). The National Animal Identification System (NAIS) is a national premises registration, animal identification, and animal tracing program for owners of livestock. NAIS is a national program run by the United States Department of Agriculture (USDA), but is being implemented primarily at the state level.

As for human beings, an estimated 300 Americans and 2,000 people worldwide have been implanted with microchip transponders. This chipping apparently proceeded with the full consent of the implantees until early 2007, when the VeriChip Corporation began implanting Alzheimer’s patients and their caregivers with microchips as part of a research study. These patients have reduced mental capacity and are unlikely to understand what is being done to them.

It appears that few people undergoing microchip implantation have been told about the potential health risks associated with the device. In fact, up until September 2007, almost three years after FDA approval, no mention had been made by the company or the FDA in relation to the well-established, though generally under-reported, finding that the microchip caused cancer in laboratory mice and rats.

Microchip-Induced Cancer in Mice and Rats

In at least six studies published in toxicology and pathology journals between 1996 and 2006, researchers found a causal link between implanted microchip transponders and cancer in laboratory mice and rats. The tumors were typically sarcomas, including fibrosarcomas. Other cancers found included rhabdomyosarcoma, leiomyosarcoma, malignant fibrous histiocytoma, mammary gland adenocarcinoma, malignant schwannoma, anaplastic sarcoma, and histiocytic sarcoma.

In almost all cases, the tumors arose at the site of the implants and grew to surround and fully encase the devices. In several cases the tumors also metastasized or spread to other parts of the animals, including the lungs, liver, stomach, pancreas, thymus, heart, spleen, lymph nodes, and musculature of the foreleg.

The tumors generally occurred in the second year of the studies, or after half a lifetime’s exposure to the implant. At the typical time of tumor onset the animals were in middle to advancing age. The exception to this was the Blanchard (1999) study, in which genetically modified mice developed fast-growing cancers well before six months.

The percentage of mice and rats developing microchip-induced tumors in the six studies reviewed ranged from 0.8% to 10.2%. Several researchers, including Elcock et al. (2001), Le Calvez et al. (2006), and Tillmann et al. (1997) suggest that the actual rate of tumor formation may have been higher than was reported in their studies, since they examined only visible lesions and thus may have missed microscopic changes that signaled the onset of additional tumors around the implants.

Elcock et al. (2001) write, “It should be noted … that these tumor incidences only approximated the potential incidence of microchip-induced tumors for these studies. The original intent of the studies was to characterize the toxicological profile of the chemical test substance in question, therefore tissue surrounding the animal-identification microchips was not examined microscopically unless there was a gross lesion. Thus, small pre-neoplastic or neoplastic lesions may have been missed” (p. 488).

A similar observation was made by Le Calvez et al. (2006). In their study 4.1% of animals developed visibly detectable tumors. However, researchers suspected the actual incidence of cancer may have been higher, had they looked at tissue samples. Tillmann et al. (1997) also write that “only implantation areas with macroscopic findings have been examined microscopically, so that possible pre-neoplastic lesions could have been missed” (p. 200).

Microchip-Induced Cancer in Dogs

In addition to the six studies that identified cancer in rodents, two studies evaluated cancerous tumors (fibrosarcoma and liposarcoma) that developed in dogs at the site of microchip implants. In one case, the tumor was attached to the implant. In the other case, the tumor completely encased the microchip.

Microchip Studies in Which No Cancer Was Found

Included in this review are three studies, one involving dogs, one involving rats, and one involving mice, in which none of the animals developed cancer from the microchip implant. Though these studies were originally presented as evidence that implantable microchip devices were safe, they suffer from methodological limitations that call their statistical validity into question. These limitations include the small number of animals used and the short duration of the studies. Those issues are discussed at further length in this document.

Overall Cancer Incidence

Tables 1 and 2 summarize the results of the 11 studies reviewed in this Chapter. Table 1 lists the cancer incidence from eight studies where cancer was found in connection with a microchip implant. Table 2 lists details from the three studies in which no cancer was found.

Animals Used in the Research

Toxicology and carcinogenicity researchers rely on laboratory animals to help determine which substances are safe and which are potentially harmful. Since most substances that cause cancer in humans also cause cancer in mice and rats, these animals can serve as an early indicator that a substance may not be safe for use in humans.

Several different strains of laboratory mice and rats were evaluated in the rodent studies reviewed in this report and several breeds of dog were included in the dog studies reviewed. A listing of the animals involved in each research study has been provided in Table 3.

Animals in the first group of prior studies developed microchip-induced tumors. Animals in the second group did not develop tumors. The third group of studies pertain to dogs that developed cancer around or attached to microchip implants.

Rodents used in laboratory studies are specially bred for uniformity and hardiness. They are utilized in cancer studies for their ability to respond to carcinogenic substances while remaining relatively free from spontaneous tumors that are unrelated to carcinogenic test substances.

The B6C3F1 mouse was the most commonly used mouse in these studies, appearing in four of the eight rodent studies. The Handbook of Carcinogen Testing (Milman & Weisburger, 1994) states that National Toxicology Program studies use the B6C3F1 mouse almost exclusively for cancer research because of its desirable characteristics. The Handbook describes the mouse as “hardy, easy to breed, disease resistant, and [having] a low spontaneous tumor incidence at most sites” (p. 353).

The p53+/- mouse contains a genetic mutation in the p53 gene which normally sends protein to help repair damaged cells. In these mice, one allele, or portion of the gene has been deleted, thus increasing their susceptibility to cancer caused by genotoxins, or substances that damage genetic material. p53+/- mice are not known to develop spontaneous cancers in the first six months of life and are expected to only develop cancer in the presence of genotoxins. The high rate of cancer development around the microchip implant in p53+/- mice at less than six months suggests that the implant may have genotoxic attributes.

The CBA/J mouse is an inbred strain that is widely used as a general purpose laboratory animal. It suffers from hereditary blindness, making it of interest to vision researchers, and it is often selected for other studies because of its low incidence of mammary tumors (The Jackson Laboratory). The CD-1 (albino) mouse is described as a “general multipurpose model [for] safety and efficacy testing, aging, surgical model, [and] pseudopregnancy” (Charles River Laboratory, 2007, p. 15).

The Sprague-Dawley rat is described as “a general model for the study of human health and disease” and an “excellent model for toxicology, reproduction, pharmacology, and behavioral research areas.” They have a life span of 2.5 – 3.5 years (Ace Animals, Inc., 2007).

The Fischer 344 rat is described as the “most widely used inbred rat strain, particularly for toxicology and teratology” studies (Simonsen Laboratories, 2007).

Microchips Used in the Research

The glass used to encapsulate the microchip is known as “bioglass,” a material widely used in animal studies due to its insolubility and apparent biocompatibility (Vascellari et al., 2004). Bioglass is comprised primarily of “silicon, sodium, calcium, potassium, magnesium, iron, and aluminum” and has been classified in the silicon sodium group (Vascellari et al, 2004, p. 188; citing Jansen et al., 1999).

The microchip transponder comes prepackaged in a sterile 12-gauge injection needle attached to an implantation device supplied by the manufacturer. Once the transponder is embedded in the body, it can be interrogated by a reader device that emits radio-frequency energy. This energy stimulates the embedded transponder, causing it to emit a signal that is captured by the scanner and translated into an identification code.

The microchips used in these studies were obtained from several distributors, including BioMedic Data Systems, Inc., Destron Fearing, and Merial, as indicated in Table 4.

REVIEW OF STUDIES: MICROCHIP-INDUCED CANCER IN LABORATORY RODENTS AND DOGS: EIGHT STUDIES FROM 1996 TO 2006

Le Calvez et al., 2006

Subcutaneous microchip-associated tumours in B6C3F1 mice: A retrospective study to attempt to determine their histogenesis. -Experimental and Toxicologic Pathology. 2006; 57:255–265.

Most of the animals with microchip-associated tumors died prematurely … due to the size of the masses [or] the deaths were spontaneous and attributed to the masses. (p. 258)

One of the most potentially serious disadvantages of the microchip implantation is the possibility that foreign-body-induced tumours may develop … (p. 256)

Summary

Microchips were implanted into 1,260 experimental mice for identification purposes. Two years later, 4.1% of the mice had developed malignant (cancerous) tumors at the site of the microchip implantation (Table 5). The cancers were directly attributed to the microchips. In one subgroup, the cancer rate among the chipped mice was 6.2%.

Study Design and Key Findings

1,260 mice were separated into groups for use in three oral carcinogenicity studies. The first study involved 550 mice, 110 of which received only a microchip implant. The other 440 received a microchip implant along with a low, medium, or high dose of a chemical test substance in their feed.

Two years later, 34 of the mice (6.2%) had developed malignant (cancerous) tumors around or adjacent to the microchip. These tumors occurred across groups, appearing in control mice as well as mice that had received the ingested chemical. Researchers plainly identified the microchip as the cause of the tumors.

The second study involved 600 mice. 120 received only a microchip, while the other 480 received a microchip combined with varying doses of a chemical compound in their feed. Two years later, 14 out of the 600 mice (2.3%) had developed cancerous tumors related to the microchip. For the test group of 480 mice, these tumors were determined to be unrelated to the ingested compound.In the third study, 110 mice were implanted with a microchip and received no other intervention. Four of these animals (3.6%) developed a tumor around the microchip.

The researchers suggest the actual cancer rate may have been higher than reported, as they tested for cancer only when visible abnormalities were seen in the mice. Smaller tumors in the early stages of development that were not yet visible to the naked eye may have been missed. According to the authors, “as these were only sampled and examined histologically when gross abnormalities were noted, it is possible that early reaction could have been missed. These incidences may therefore slightly underestimate the true occurrence” (p. 258).

Additional Findings

• • All the cancerous masses found either contained the microchip or were adjacent to it. An empty capsule where the microchip had been was frequently identified as the origin of the tumor. The researchers wrote:

All sarcomas were characterized by a poorly delineated, non-encapsulated, densely cellular mass, located in the subcutis but frequently infiltrating the panniculus muscle and various layers of the skin with occasional ulcerations. A round-to-oval empty space of 2 mm diameter corresponding to the cast of the microchip was frequently seen and associated with a vestigial fibrous capsule and/or a focus of necrosis. (p. 261)

• • Tumors were initially identified by morphology as fibrosarcoma (17 cases), rhabdomyosarcoma (12 cases), leiomyosarcoma (2 cases), malignant fibrous histiocytoma (3 cases), mammary gland adenocarcinoma (2 cases), and other sarcomas (16 cases). Researchers later redefined the tumors as “sarcomas not otherwise specified (NOS) with a large myofibroblastic component” (p. 255) after additional testing. A sarcoma is a malignant tumor of soft tissue that connects, supports or surrounds other structures and organs of the body.
  
• • Once initiated, the tumors grew rapidly. Most of the animals that developed microchip-associated tumors died prematurely as a result of the tumors.
  
• • Four microchip-related cancers metastasized (spread) to the lungs, liver, stomach or pancreas.
  
• • Many of the implants migrated from the original implantation site on the back of the mice to cause cancer at other locations in the body. Nineteen percent of the cancers found involved microchips that had migrated from the back to the limbs, abdomen, or head of the mice.
  
• • A test procedure known as desmin staining found that the tumors often infiltrated nearby muscle tissue and that there was “an extensive cavernous network of capillaries within the tumour, especially around the hole left by the microchip.” (p. 261)

Study Details

• • The study was conducted at MDS Pharma Services in L’Arbresle, France.
  
• • Animals used in the study were B6C3F1 mice from Charles River Laboratory.
  
• • Microchip implants were from BioMedic Data Systems Inc. and were described as “hermetically sealed in a cylindrical inert glass capsule measuring 12 mm in length and 2 mm in diameter and partially covered on a length of 5 mm by a porous polypropylene polymer sheath as an antimigration measure.” (p. 255)

Vascellari, Melchiotti, and Mutinelli, 2006

Fibrosarcoma with typical features of postinjection sarcoma at site of microchip implant in a dog: Histologic and immunohistochemical study. -Veterinary Pathology. 2006; 43:545–548

Reports on adverse reactions to vaccination and microchips are strongly encouraged to deepen the current knowledge on their possible role in tumorigenesis . . . the cause and effect relationship between exposure (injection) and outcome (sarcoma) is still to be defined and is a matter of discussion for experts. (p. 547)

Summary

A 9-year-old bulldog developed a cancerous tumor (fibrosarcoma) adjacent to a microchip implant approximately seven months after being implanted with the device (Table 6). Researchers attributed the tumor to either the microchip or to vaccinations at the site, and called for better reporting of adverse reactions to microchip implants and vaccinations.

Overview

In September 2003, Leon, a 9-year-old male French bulldog was implanted with a microchip for identification purposes. In April 2004 (8 months later) Leon’s owner detected a lump measuring 3 cm x 3 cm (1.2 x 1.2 inches) in the implant area. The mass was surgically removed and subjected to laboratory analysis whereby it was identified as a high-grade infiltrative fibrosarcoma – a malignant and fast-growing form of cancer. It was found attached to the microchip. Leon later died from complications that his owner attributes to the cancer.

The microchip is implanted into dogs through an injection procedure involving a 12-gauge needle. The researchers suggest the tumor may be a form of post-injection sarcoma, involving an inflammatory reaction around an injection site that predisposes the tissues to tumor development. The researchers note that “irritation, inflammation, and/or wounds [promote] tumor development. Virtually anything that causes a local inflammatory reaction may potentially be responsible for neoplastic initiation [i.e., abnormal proliferation of cells]” (p. 546).

The authors attributed the cancer to either the microchip or to vaccinations the dog had received at the same site. They wrote: “It is difficult to establish which was the primary cause of the neoplastic growth, because the dog had received several rabies vaccines and the microchip was detected close to but not included in the mass” (p. 547).

The investigators conclude by stating that “reports on adverse reactions to vaccination and microchips are strongly encouraged to deepen the current knowledge on their possible role in tumorigenesis [causing tumors],” calling it “a matter of discussion for experts” (p. 547).

It should be noted that a complete physical exam found nothing other than the detected lump to indicate that Leon had developed cancer. No evidence of inflammation or sepsis were found at the site of the implant. Had Leon’s owner not insisted on a microscopic evaluation of the unusual growth, his cancer might never have been detected.

Study Details

• • The evaluation was conducted by Dr. Marta Vascellari of the Instituto Zooprofilattico Sperimentale delle Venezie at Viale dell’Universita in Legnaro, Italy, with associates Erica Melchiotti and Franco Mutinelli.
  
• • The microchip was manufactured by Digital Angel, the parent company of the VeriChip Corporation, and distributed by Merial under the Indexel® brand, through Lyon, France. Digital Angel’s website states: “Digital Angel manufactures implantable RFID chips used in pets around the world … In Europe, our product is distributed by Merial in some countries under the Indexel® brand. For more information, visit merial.com.” (Source: http://www.digitalangelcorp.com/dac_pets.asp. Accessed July 23, 2007.)
  
• • Merial’s website states: “Merial is a world-leading animal health company. We are a forward-looking company with a proven track record, producing pharmaceutical products and vaccines for livestock, pets and wildlife.” (Source: http://www.merial.com/our_company/index.asp. Accessed July 23, 2007.)

Vascellari et al., 2004

Liposarcoma at the site of an implanted microchip in a dog. -The Veterinary Journal. 2004; 168:188–190

The intact microchip was found completely embedded within the mass . . . [and] a diagnosis of low-grade liposarcoma was made. (p.188)

Veterinary surgeons are . . . encouraged to check the microchips that have been implanted in pets at least annually, such as when they come in for vaccinations, and report any adverse reaction. (p. 190)

Summary

An 11-year-old dog developed a cancerous tumor (liposarcoma) around a microchip that had been implanted approximately 19 months earlier. The tumor was removed and the dog recovered (Table 7).

Overview

In April 2000, a male mixed-breed dog was implanted with a microchip for identification purposes. In November 2001 (19 months later) the dog’s owner detected a firm, painless lump at the implant site measuring 10 x 6 cm (approximately 4 x 2.5 inches). The lump was examined by a veterinarian who determined that the microchip was completely embedded within the mass.

In April 2003, the tumor was surgically removed under general anesthesia. Upon microscopic examination, it was identified as a malignant liposarcoma, an aggressive and invasive type of cancer that can metastasize to the lungs, liver, and bone. The researchers note that liposarcoma is uncommon in dogs.Prior to the surgery, the dog had shown no visible signs of cancer other than the unusual lump. Blood tests run on the dog, including a complete pre-operative blood count and serum biochemistry analysis, did not detect that the mass was malignant. Thoracic radiographs (chest X-rays) were also normal. Had there not been a microscopic evaluation of the unusual growth, the cancer might not have been detected.

Study Details

• • The evaluation was conducted by Dr. Marta Vascellari and Franco Mutinelli of the Instituto Zooprofilattico Sperimentale delle Venezie, Histopathology Department, in Legnaro, Italy, together with veterinary surgeons Romina Cossettini and Emanuela Altinier of Porcia, Italy.
  
• • The microchip was manufactured by Digital Angel, the parent company of the VeriChip Corporation. It is distributed by Merial under the Indexel® brand. Researchers state that the implant “consists of a sealed glass capsule containing a chip and a coil . . . [and is] equipped with an anti-migrational capsule, located in the anterior part of the microchip.”

Elcock et al., 2001

Tumors in long-term rt studies associated with microchip animal identification devices. -Experimental and Toxicologic Pathology. 2001; 52:483–491

Electronic microchip technology as a means of animal identification may affect animal moribundity and mortality [i.e., illness and death rates], due to the large size and rapid growth of microchip-induced tumors as well as the occurrence of metastases. (p. 491)

Most tumors arising from foreign bodies are malignant . . . and have a rapid growth rate, killing the animal in a matter of weeks. (p. 491)

Summary

Microchips were implanted into 1,040 rats for identification purposes. After two years, just under 1% of the rats developed malignant tumors (malignant schwannoma, fibrosarcoma, anaplastic sarcoma, and histiocytic sarcoma) surrounding the implants. The researchers attributed the tumors to the presence of the microchip, and referred to them as “microchip-induced” (Table 8).

Study Design and Key Findings

A group of 1,040 rats was implanted with microchip transponders and then divided into two random groups. Half were exposed to an ingested chemical compound at high, medium, and low doses; the other half received no compound. By the end of the second year, eight of the rats that received the compound, or 0.77%, had developed malignant tumors at the site of the microchip implant.

Though the affected rats had all been dosed with a test substance, the tumor incidence was distributed across dose groups and showed no test-substance-related trends. Stated slightly differently, higher levels of chemical compounds in the animals’ feed did not correspond to higher tumor rates.

Further clarifying that the tumors had arisen in response to the microchips, not the test compound, the investigators wrote: “the process of differentiating microchip-induced tumors from suspected compound-related tumors was fairly easy in the cases described here, for all contained the embedded microchip device” (p. 491).

Additional Findings

• • The microchip-induced tumors were identified as malignant schwannoma, fibrosarcoma, anaplastic sarcoma, and histiocytic sarcoma. All diagnoses were confirmed with immunohistochemistry.
  
• • All masses were confined to the area of microchip implantation and contained embedded microchips.
  
• • Some masses were extremely fast-growing, enlarging as much as 1 cm per week. Several tumors metastasized to regions including the lungs, thymus, heart, lymph nodes, and musculature.
  
• • Five of the eight affected animals died as a direct result of the microchips.
  
• • All tumors occurred in the second year of the study. The average age at tumor onset was 585 days, or approximately one year and seven months. (The average life span of a rat is two to three years.)
  
• • The researchers write that: “Although the resulting tumor rate was observed to be low, the overall health of the affected rats was compromised due to tumor size and the occurrence of metastases, leading to early sacrifice” (p. 484). In other words, the animals’ health was so poor due to large, malignant tumors spreading through their bodies that researchers were forced to kill them prematurely.

Study Details

• • The study was conducted by Laura E. Elcock of Bayer Corporation in Stilwell, Kansas. Other investigators were Barry Stuart, Bradley Wahle, Herbert Hiss, Kerry Crabb, Donna Millard, Robert Mueller, Thomas Hastings and Stephen Lake. The results were peer-reviewed by an independent pathologist.
  
• • Animals used were Fischer 344 laboratory rats.
  
• • Microchip implants were from BioMedic Data Systems Inc.

Blanchard et al., 1999

Transponder-induced sarcoma in the heterozygous p53+/- mouse. -Toxicologic Pathology. 1999;27(5):519 -527

There was an unequivocal association between the [microchip implant] transponder and sarcoma that was unrelated to drug treatment. (p. 526)

The presence of the foreign body [microchip transponder] may elicit tissue reactions capable of generating genotoxic byproducts. (p. 526)

Summary

177 genetically modified mice were implanted with microchips for identification purposes as part of a chemical compound study. After six months, 18 of the mice (10.2%) had developed malignant tumors (“undifferentiated sarcomas”) around the microchip (Table 9). The tumors occurred in both experimental and control animals. The researchers reported an “unequivocal association” between the implants and the cancer.

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