Thursday, August 16, 2018

Research Shows DDT Causes Increased Risk of Autism

New research published August 16, 2018 shows elevated levels of a dichlorodiphenyltrichloroethane (DDT) metabolite called p,p′-dichlorodiphenyl dichloroethylene (p,p'-DDE) in pregnant women, as the first biomarker implicated in autism in children. This research shows  a significant increased risk for autism when a pregnant mother is exposed to DDT. The odds of autism were nearly one third higher among offspring of mother's with DDE levels that were in the highest 75th percentile, after adjusting for maternal age, prior offspring, and history of psychiatric disorders. The research writers said, the findings "provide the first biomarker-based evidence that maternal exposure to insecticides is associated with autism among offspring." The scientists controlled for many other risk factors and had a large group of 1500 women.

Although banned in many countries DDT is still present in the environment and found in blood and tissues.  It persists in tissues and pregnant women pass it along to their baby.

DDT was banned in the United States, but there are sites contaminated with this pollutant that pregnant woman may be living in proximity to. Additionally, there are countries still using it in agriculture and to kill vectors of disease such as mosquitoes. It has a 1/2 life of 15 years. This means as much as 50% can remain in the soil 15 years after application. DDT can concentrate in the food chain. It persists in the environment and accumulates in fatty tissues. Its metabolite DDE is found  in the blood, semen, bones, brains, fat tissue and fatty organs, and other organs of the body. It has been found in the Arctic air, Arctic water and Arctic organisms. It has been linked to the development of breast cancer, Alzheimers, infertility, sperm abnormalities, impairment of neurodevelopment in children, and even obesity. The countries that have banned DDT include Argentina, Australia, Bulgaria, Canada, Colombia,Cyprus, Ethiopia, Finland, Hong Kong, Japan, Lebanon, Mozambique, Norway, Switzerland, and the USA. Countries that have severely restricted its use include Belize, Ecuador, the EU, India, Israel, Kenya, Mexico, Panama, and Thailand. In 2004, the Stockholm Convention on Persistent Organic Pollutants restricted the use of DDT. 170 countries ratified the convention.

Why are we still using it? In 2015 there were over 200 million new cases of malaria in India, with over 400,000 registered deaths. Most of these cases occur in the rural areas. Today, India and sub-Saharan African countries account for over 80% of the malaria cases globally.  Although many countries had restricted the use of DDT, in 2006, the World Health Organization (WHO) supported the indoor use of DDT in African countries where malaria remained a major challenge. WHO stated that the benefits of the pesticides to African countries outweighed the adverse effects it had on the environment. India and North Korea have continued the use of the pesticides for agricultural use despite the agricultural ban. DDT and its metabolites have been detected in food from all over the world and this route is likely the greatest source of exposure for the general population.  

Approximately 4,000 tons of DDT are produced annually to control vectors of disease - largely mosquitoes. It is legal to manufacture DDT in the U.S., though it can only be exported for use in foreign nations. DDT can only be used in the U.S. for public health emergencies, such as controlling mosquito born disease. Today, DDT is manufactured in North Korea, India, and China. India remains the largest consumer of the product for vector (mostly mosquito) control and agricultural use. China produces 4,500 metric tons of the product of which 80–90% is used to produce Dicofol, an acaricide (kills arachnids - ticks and mites mostly). African countries do not use the product for agricultural purposes but countries such as Ethiopia, South Africa, Uganda, and Swaziland use it to control malaria. If you eat non-organic food from a country that still uses DDT, you could be ingesting it. Some people have reported it being sprayed on planes in India also.

More data on DDT can be found at EWG 

Additional notes:

There are other insecticides and herbicides that may be implicated in autism.  Certainly there appears to be a correlation between the increased use of glyphosate (RoundUp®) since the 1990's and the increased rates of autism that we see in the United States. I would like to see thorough research on the possible relationship between glyphosate and autism.

The research showed no association between total maternal levels of polychlorinated biphenyls (PCBs) and autism. 


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