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Welcome to Consultox, Limited, a toxicology consulting firm established in 1985. Dr. Richard A. Parent, Principal and Consulting Toxicologist, is a doubly Board Certified Toxicologist with a firm foundation in chemistry and over 30 years of practice in the field of Toxicology. Consultox is a full service toxicology consulting firm providing support to litigants as an Expert Witness in Toxicology and to industry as an Independent Toxicology Consultant for projects involving product safety, drug impurities, risk assessment, and various agency product registration processes.

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Expert Witness Toxicologist

Richard A. Parent, PhD, DABT, FATS, RAC, ERT, is certified by the American Board of Toxicology and the Academy of Toxicological Sciences as well as the Regulatory Affairs Certification Board. He is a recognized Expert in Toxicology in France and the European Community. Dr. Parent has over 35 years of experience in Toxicology and Chemistry and has directed two toxicology laboratories, the combination of such affords him insights that go far beyond his fields of dual expertise. Read More

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Ranitidine, sold under the name of Zantac, is a medication that decreases stomach acid production. Zantac has recently been found to contain nitroso-dimethylamine (NDMA), a well-known carcinogen. The fact that NDMA causes cancer has been known since the 1950s, and its presence in Zantac is alarming. Nitrosamines in general were thought to increase the risk of cancer based on several animal studies. Early on, the International Agency for Research on Cancer (IARC) classified nitrosamines as probable human carcinogens, as has the EPA. NDMA is found at low concentrations in some foods such as cured meats, tobacco, and in some household products. The US FDA has suggested a limited daily exposure to NDMA of 96 nanograms (a nanogram is one billionth of a gram). One study reported an NDMA content in Zantac in excess of 2 million nanograms per tablet, while another study using simulated stomach acid containing Zantac reported an NDMA content of 300,000 nanograms per Zantac tablet which is still 3000 times the FDA's recommended daily intake limit.

There is some evidence that the active ingredient in Zantac, ranitidine, imported from India and China, included NDMA as a contaminant. There are still other reports that ranitidine, the major component of Zantac, may breakdown forming NDMA on its own. One study reported a significant concentration of NDMA in urine after ingesting ranitidine. Both sources of NDMA may be appropriate to consider, but its presence in such high levels in Zantac tablets puts the users of this medication at high risk of developing cancer.

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Dr. Richard A. Parent has given testimony in courts in the United States and Canada nearly 30 times, and he has been deposed over 120 in support of both plaintiff and defense. Cases cover a wide range of subjects: dramshop, diacetyl (popcorn lung), wrongful death related to methadone and carbon monoxide, personal injury involving ozone, carbon monoxide, benzene, sulfur dioxide, chlorine, 1,4-dioxane, alcohol, arsenic, and others. Dr. Parent has lectured on the requirements for the establishment of causation and the structuring of expert reports. Many redacted reports are included on this website for review. Read More


Dr. Richard Parent has assisted clients in areas of product safety relating to toys, cosmetics, household products, pesticides, OTC drugs, art supplies, and food additives (GRAS).  He has worked with appropriate agencies to meet requirements for labeling and warnings as well as creating material safety data sheets (MSDS) for various industrial products.  He has been involved in assessing risk in occupational situations where potentially hazardous substances are involved and preparing submissions in support of food additives in accordance with the GRAS procedures.  Of particular interest is Dr. Parent’s area of specialization in Inhalation Toxicology and his significant contribution to the field through the publication of his book, “Comparative Biology of the Normal Lung”, a well respected source of normal parameters related to lungs of various animal species, including man.

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