Most of the labeled uses of DDT (dichlorodiphenyltrichloroethane) in the U.S. were cancelled in 1972 by the newly created U.S. Environmental Protection Agency. DDT was one of the first, if not the first, pesticide that was cancelled for environmental reasons. Research showed that the fat-soluble breakdown products of DDT were stored for long periods of time in the fat of animals. Most animals do not easily release this fat, so the DDT products release only slowly, if at all, and usually do not seriously affect the physiology of the animal. However, when the animal is eaten by a predator or scavenger, these DDT products concentrate in a process called biomagnification. Top-level predators can accumulate comparatively high levels in their fat.
An exception to the fat retention process in animals occurs in birds. When a female bird enters her reproductive phase, almost all of the fat is consumed by her body to produce eggs. In top-level predatory birds, such as the bald eagle, osprey, peregrine falcon, and brown pelican, enough DDT products are released at once to cause dead embryos and thin eggshells that break easily, killing the chick. During one year several decades ago when DDT residues were still very high, it was determined that only two brown pelican chicks were raised along the California coast. Inspection of hundreds of nests revealed prematurely broken eggs and dead embryos in unhatched eggs. On November 17, 2009, the brown pelican on the Pacific coast of North America was delisted from the Endangered Species List. It has been determined that the species has recovered sufficiently to no longer require the protection of the Endangered Species Act.
The peregrine falcon was delisted due to recovery from the Endangered Species List in 1999, and the bald eagle in the lower 48 states was similarly delisted in 2007. Although habitat recovery and other factors helped these species recover to healthy population numbers, the degrading DDT residues are also considered to be a major contributing factor.
Today, many people are of the opinion that DDT is very toxic to humans. However, among insecticides, DDT is relatively low in toxicity. There has been some research indicating DDT residue as a possible human endocrine disruptor; however, further research has not substantiated these findings. Although DDT residues continue to be found in human mothers' milk, the levels continue to fall and are not considered to be important compared to the value of the milk to infants.
The following was written by Andrew Thostenson, the Pesticide Program Specialist for North Dakota State University. It provides important insight into the history of DDT usage. An interesting sidelight to the following is that part of the reason we are having bed bug problems today is cross-resistance to pyrethroid insecticides from DDT and other organo-chlorine insecticide resistance developed by bed bugs decades ago.
"Veterans of my pesticide trainings will recall that I often play video clips from the late 1940s and early 1950s showing widespread and seemingly indiscriminate use of DDT insecticide, especially in urban settings. I was trying to make the point about why we don't do things like we used to. While this helped me drive home the point as to why we should take more precautions, I always was bothered about why they sprayed so much of that stuff back then.
"One of my hobbies is history, so I went on a hunt to understand what they were trying to do. First, you have to understand that before World War II, living with flies, mosquitoes, bed bugs, lice and fleas was more or less the facts of life. So also was polio, malaria, yellow fever, typhus, itching after a hotel stay, plagues and other unpleasant facts of life (and even premature death). This was simply the way it was in the "good old days."
"That all changed with the introduction of DDT during the war. For the first time, soldiers did not die from these maladies because their uniforms were impregnated with DDT, they dusted their bodies in DDT, and the Army Air Corps and Navy bombed friendly bases and even entire cities from the air with DDT. All of this was done to kill insects that spread diseases to allied troops or civilian populations. The results were astonishing and, by 1945, word spread back to the civilian population in the U.S. that this miracle powder was being used. Soon basement laboratories were set up to synthesize DDT so it could be sold on the black market (wartime rationing prevented it from being marketed over the counter). After the war, late in 1945, surplus Army/Navy DDT was being sold legally at prices that were next to nothing.
"By 1946, public health districts, state health departments and federal health agencies began to think in terms of wiping out certain insect-borne diseases with DDT. Yellow fever, a disease that killed tens of thousands of people annually in the U.S. and nearly prevented the Panama Canal from being completed, was eradicated. Malaria, though a tougher nut to crack, was eliminated by about 1950. In 2009, imagining what this meant to people living in that time is difficult. But for them, the elimination of these diseases must have been incredible, miraculous, a godsend – the adjectives and adverbs can go on and on.
"The success in the eradication of malaria from the U.S. soon led the Rockefeller Foundation to propose a worldwide crusade to rid the world of malaria. In developed nations, the crusade largely was successful, but the world is a pretty big place and, by 1962, the foundation abandoned the idea of worldwide eradication mostly due to cost.
"DDT's success at controlling insect-transmitted diseases led to other applications, some of them were logical and realistic, such as protecting crops. But on the other hand, some proposed uses were almost fantastic or even crazy. Take the plan by the Iowa Department of Agriculture in 1947. The department decided to wipe out flies. Department officials thought they could do it in spite of the fact that Iowa's livestock industry produced manure, which the flies thrived upon, by the billions of tons. In a Time magazine article, they reported:
'The program, headed by the state's agricultural and health authorities, will take on all the trappings of a civic crusade. Local chambers of commerce, boards of health, Rotary and Kiwanis Clubs will march on the flies in close ranks. In northern Iowa a mechanized column of 40 former G.I.'s is training with pressure spray outfits. They plan to hit Mason City on June 9, DDT-ing the whole town fly-less in two hours by the clock. Toxic ammo of the anti-fly movement is good new DDT, which will be sprayed on cattle, barns, downtown restaurants, garbage pails, old-fashioned outhouses.'
"While the Iowa anti-fly campaign seems farcical by today's standards, the folks dealing with polio outbreaks in the late '40s and '50s were desperate. Polio was killing and maiming tens of thousands of Americans per year and the doctors could not tell people how to protect themselves. When word got out that the polio virus has been found on the hairs of the common housefly, people turned to DDT.
"An example of this is the Texas town of San Angelo with a population of just less than 60,000 people. In 1949, the city fathers acted to stop the summer polio epidemic by wiping out house flies. In a 2005 thesis by J.C. Lee, written for his master of arts degree at Texas State University, he described the following: 'The most drastic measure was the repeated spraying of the entire city with DDT, which at the time was considered a completely viable health measure for controlling polio.
That same summer San Antonio authorities regularly used helicopters and planes from the Texas Air National Guard to fumigate the entire city with insecticide. Though many of the citizens wanted it, San Angelo decided not to use airplanes. Their concern was not that people might have allergic reactions to the insecticide, but that it would cost the city upwards of $38,000 dollars, and that much of the spray would probably blow away.
Officials also argued that air spraying would waste DDT, since it would not get down into trash piles and alleyways where it needed to go. Airborne spraying, they reasoned, would only waste the insecticide on roofs and treetops. Instead, the city opted to use a pair of foggers on the ground. One was borrowed from Abilene, and another was bought brand new. They were towed behind pickup trucks and boasted a hundred-gallon tank that lasted for eight hours. Throughout the summer the entire city was sprayed several times by the foggers.'
"People were so desperate to protect their children from polio that they lined up by the thousands at hardware stores to fill their jars with DDT purchased by the city and the March of Dimes Foundation. Afterwards they went home and sprayed their outhouse and garbage cans, and they literally bathed themselves and washed their clothes with the miracle powder. While the benefits of using DDT to suppress polio were marginal at best, Lee talks about people feeling "comforted" because at least they were doing something.
"So after a summer of reading, I found my answer as to why they sprayed DDT on such a massive scale. Sure, they used it out of fear and because it seemed like it would be nice to not have flies during an Iowa summer. But mostly they did it because it made sense. DDT saved lives and it helped feed a war-ravaged world. Makes sense to me. But I wonder if in our smug world of environmental impact statements, endangered species protections, Clean Water Act permits and pesticide reregistration eligibility decisions, do we ever think about what going back to the "good old days" would be like?"
(Phil Nixon, Andrew Thostenson)
A Utah family hired a certified applicator to control voles in their yard. Shortly after, both of their daughters, a four-year old and 15-month-old, died – three days apart. The entire family was hospitalized for flu-like symptoms. The older child died on the first day, but the others were released the next day. However, the younger child fell ill again later that day. Authorities suspect that the applied phosphine is to blame.
About 1 ½ pounds of Fumitoxin (aluminum phosphide) pellets were dropped in burrows along the sidewalk leading to the front porch. The sidewalk application was within seven feet of the front door and within three feet of the garage. However, the label requires a 15-foot distance from any structure that may be occupied by people or animals, especially homes.
The authorities are speculating that the phosphine collected in an open space under the stairs to the porch and seeped into the house. A hazardous materials cleanup team from the Utah National Guard was called to the scene. Crews found elevated levels of phosphine in the entryway, the garage, and in what appeared to be a child's bedroom.
In the summer of 2007, Phostoxin killed a two-year-old when a Texas family was trying to kill the cockroaches in their home. They applied pellets that were for use only in large grain bins. Please see the September/October 2007 issue of IPR for the article.
Sometimes when we apply pesticides, we think that those pages and pages of "minor" details listed on the label won't matter in the grand scheme. What could go wrong? Aren't the manufacturers being a little too precautious with their required setback restrictions? Not so. Those label warnings are there for a reason and it's in everyone's best interest to abide by them. One person's mistake can affect the lives of many. As a mother of two toddlers, this is an unfortunate tragedy I won't forget anytime soon.
(Submitted by Michelle Wiesbrook. Sources: The Salt Lake Tribune, 2/10/2010 and Pesticide Reports, March 2010, Oklahoma Cooperative Extension Service.)
EPA has released a policy paper to update and strengthen risk assessments and include risks to agricultural workers and children of workers in agricultural fields. The assessment will also include risks from non-food uses of the products.
The risk assessment techniques that were developed for the Food Quality Protection Act of 1996 (FQPA) will be used for any pesticide risk assessment, even if it does not fall under FQPA. This would include:
• Reporting potential risks for individuals who had not been explicitly considered; specifically workers aged 12 to 17 and children taken into agricultural fields while their parents work.
• Considering cumulative effects that may occur from exposure to multiple pesticides with a common mechanism of toxicity.
• Considering aggregate exposures to pesticides from multiple sources.
• Using an additional safety/uncertainty factor to protect children.
The comment period ends on April 12, 2010. More information is available at: http://www.epa.gov/pesticides/health/worker-rsk-assmnt.html. At this link is the 10-page policy paper that discusses the issue in detail.
Some highlights include:
• EPA contends that the state of the science since FQPA has advanced to the point that it is now possible to consider aggregate risks from the same pesticide used in agricultural, commercial, and/or residential settings; cumulative risks from exposure to pesticides with common mechanisms of toxicity; and the unique risks posed to infants and children due to their potentially increased sensitivity to pesticides.
• The principal group that has not been addressed using advanced risk assessment techniques is agricultural workers and their children who may accompany them to work.
• EPA's commitment to environmental justice compels it to act expeditiously to incorporate the risk assessment techniques developed in the implementation of the FQPA in assessing pesticide risks under FIFRA.
• Since the passage of FQPA, EPA has not (under FIFRA) assumed an additional 10X uncertainty factor to protect infants and children in assessing worker risks. This includes child workers and non-working children brought to the agricultural workplace by their parents. Yet a March 2000 GAO report (GAO/RCED-00-40 Pesticides: Improvements Needed to Ensure the Safety of Farmworkers and Their Children http://www.gao.gov/new.items/rc00040.pdf) states that at least 129,000 14- to 17-year-olds (workers under age 14 were not surveyed) were being hired to work in crop production in the United States, and that a significant percentage of farm workers with children age 5 and under occasionally took their children with them when they worked in the field (generally due to the absence of day care options).
• To provide a more comprehensive and consistent evaluation of potential risks of food use pesticides, non-food use pesticides and occupationally-related exposures, EPA intends to apply risk assessment techniques developed in the implementation of the FQPA to any pesticide risk assessment, whether falling under the FQPA or not.
• EPA intends to use safety factors in FIFRA risk assessments (e.g., including risk assessments pertaining to workers and non-food use pesticides) to address child risks where the use of safety factors is scientifically appropriate given the adequacy and results of toxicity and exposure data.
(Source: PEP-Talk, February, 2010, Pesticide Safety Education Program, Ohio State University Extension. Policy paper highlights compiled by Michelle Wiesbrook.)
This article is part 3 of a series of articles on fungicide toxicity. Please refer to the November/December 2009 and January/February 2010 issues for parts 1 and 2. If you use fungicides, this safety information will be of particular interest to you. Information on human poisoning reports was current when the source article referenced at the end of this article was printed. There could have been reports of human poisoning from these products since that time. The best way to avoid pesticide poisoning is to carefully read and follow all label directions. In the event of a poisoning, call 911 or the Illinois Poison Center at 800-222-1222.
Ethylene bis dithiocarbamates
Maneb and zineb are sold as wettable and flowable powders. Mancozeb, which is maneb with a zinc ion attached, is sold as a dust and as a wettable or liquid flowable powder. These products do NOT inhibit cholinesterase or acetaldehyde dehydrogenase. These fungicides can irritate the skin, respiratory tract, and the eyes. Possibly due to sensitivity, maneb and zineb seem to be associated with some chronic skin diseases in occupationally exposed workers.
Maneb is moderately water soluble and may be more likely to cause skin irritation. Zineb and mancozeb are basically water insoluble. Thus absorption of these two fungicides through the skin or through mucus membranes is very limited. There has been one report of zineb poisoning where the injured party already had another health problem. There have been two reported cases of maneb poisoning (one involved the eyes), but both recovered with treatment. There have been no reported cases of mancozeb poisoning. Since there are no tests for these fungicides or their breakdown products, proving zineb, maneb and mancozeb poisoning is difficult.
Captan and Folpet are moderate skin, eye, and respiratory irritants. Using test animals, folpet has been shown to cause cancer. There is strong evidence that captan can also cause cancer. No systemic poisoning has been reported with these fungicides. Captan metabolizes rapidly in the body and the resulting two metabolites can be measured in the urine.
There are many copper fungicides. Some are water soluble (including mineral oil base); some are insoluble and sold as powders and dusts. These dust and powders are irritating to the skin, the respiratory tract, and especially to the eyes, resulting in frequent reports of irritant effects to occupational workers. Since many of the copper compounds have limited solubility and absorption, there is in general a low systemic toxicity. Livestock seem to be vulnerable to copper products. Most known mammalian toxicity is based on veterinarian reports and from deliberate ingestion of copper sulfate and drinking/eating food that has been contaminated by using copper containers.
Early symptoms include a metallic taste, nausea, and pain in the upper middle area of the abdomen. More severe symptoms include vomiting blood or having bloody stools. An enlarged liver and jaundice are common. Rupturing of the red blood cells can result in collapse of the circulatory system and shock. The incidence of red blood cells that can no longer bind with oxygen, resulting in a bluish skin color, is frequently reported with the collapse of the circulatory system. Shock, renal failure, and hepatic failure are the main causes of death.
For skin contamination, wash immediately. For oral ingestion, drink a quart of milk or water and seek medical help immediately. Additional treatment for oral ingestion depends on the copper compound swallowed. If systemic symptoms appear, blood and other necessary fluids and electrolytes may need to be administered intravenously. Other health measures may be required too.
Miscellaneous Organic Fungicides
Iprodione is used on berries, grapes, fruit, vegetables, grasses, ornamentals and as a seed protectant. Low acute skin and oral toxicity is exhibited in laboratory animals. There have been no human poisoning reports.
Metalaxyl is used on soilborne fungal pathogens that attack fruit, cotton, hops, soybeans, grasses, and ornamentals. It is also used as a seed protectant. Low acute skin and oral toxicity is exhibited in laboratory animals. There have been no human poisoning reports.
Etridiazole is used on soilborne fungal pathogens and as a nitrification inhibitor. It may cause skin and eye irritation. Systemic toxicity is low. There have been no human poisoning reports.
Thiabendazole is a widely used fungicide and is used also to treat intestinal parasites. When used medicinally, it is administered at a much higher rate than is likely to be absorbed through the skin. The body rapidly metabolizes it and excretes it via urine.
After ingestion, one might have one or more of the following symptoms: dizziness, nausea, vomiting, diarrhea, fever, flushing, chills, rash, local edema, headache, hypotension, upper abdominal pain, lethargy, hearing noise in the ear when there is no noise, a sensation of tingling, pricking, or numbness of a person's skin, and liver injury (blood tests can indicate if there is liver damage). People with liver or kidney disease are more vulnerable to the toxic effects. However, there have been no adverse effects reported when thiabendazole is used at labeled rates.
Triadimefon is used on a wide range of plants including food crops. It is absorbed across the skin, but skin irritation is low. Triadimefon does cause eye irritation. Overexposure can result in hyperactivity followed by sedation.
There are no generally available laboratory tests for the miscellaneous organic fungicides or their metabolites in body fluids.
(The above material has been edited from Recognition and Management of Pesticide Poisonings, 5th Edition (1999) by James E. Schuster.)
The National Institute of Occupational Safety and Health (NIOSH) has initiated a project to learn more about barriers to effective use of personal protective equipment (PPE) (i.e. gloves, respirators, safety glasses/goggles, chemical resistant clothing, etc) among pesticide handlers and their employers. NIOSH is the federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness.
As a part of the project, NIOSH would like to be able to make direct contact with individuals who are mixing, loading, applying pesticides or who employ individuals that do. NIOSH would also be interested in speaking with family members who work on farms and assist with any of these activities.
Specifically, NIOSH is interested in hearing from individuals working to produce food, feed, and fiber plants; trees; turfgrass; flowers, shrubs; ornamentals; and seedlings.
Specific occupations include agriculture production crops; soil preparation services; crop services; farm labor and management services; landscape and horticultural services; and forestry, as well as agriculture production livestock and animal specialties; veterinary services; and fishing, hunting, and trapping. Individuals who are using fumigants in crop production and/or grain handling facilities are also included.
Information learned from this project will be used to bring attention to the barriers to PPE use and may potentially bring funding and other resources to states to help address PPE issues.
You can help by providing NIOSH with your concerns related to PPE for pesticide handlers. Perhaps you have concerns about the following that you would like to share:
• Difficulty selecting PPE for pesticides
• Understanding the term "chemical resistant"
• Identifying a "signal word"
• Matching appropriate equipment for different equipment and times of exposures
• Ability to access and acquire the proper PPE
• Understanding laws that govern PPE
• Comfort level of the PPE
• PPE effectiveness
• Function of PPE
• How easily the PPE is damaged
• PPE suitability to working activities
• Multi-tasking between activities and the need for changing or removing PPE
If you are an individual who uses pesticides, employs someone else to use pesticides, or if you provide training or support to individuals who use pesticides, please consider assisting NIOSH with this important project.
Please contact the NIOSH project director to assist; her contact information is:
Kim Faulkner PhD MPH,
National Personal Protective Technology Laboratory
P.O. Box 18070
Pittsburgh, PA 15236-0070
To learn more about both past and current projects of NIOSH, visit their website at: http://www.cdc.gov/niosh/about.html.(Michelle Wiesbrook, adapted from a North Carolina Agromedicine Institute email, 2/26/10.)
Spot-on flea and tick products have greatly increased the effectiveness of flea and tick control. These products are typically applied to bare skin between the shoulders of the pet. The hair is parted to expose the skin and the pesticide applied in a thin line or series of drops. Oral application of some of these materials is also available.
Originally provided through veterinarians, these products have been available over-the-counter in recent years in pet shops, feed stores, and similar outlets. This has reduced the cost to the consumer, but increased the likelihood for overdosing and similar problems. These products are relatively expensive, and many recent flea and tick infestations have resulted from pet owners' unwillingness to pay for these products or increasing the time between applications to the point that their effectiveness is reduced.
Generally, these pesticides are absorbed by the oil glands in the skin of the pet and released over time. Treatments are typically made monthly during flea and tick season. These pesticides provide a much higher level of flea and tick control on the pet than powders and dips. Due to their effectiveness and the attraction of fleas to the pet over humans, treated pets can even rid premises of flea infestations if allowed free access.
Cats tend to be more sensitive to some insecticides than dogs, resulting in pet species specific labeling. However, products separately labeled for cats are commonly sold in packages that are very similar in size, appearance, and labeling to those for dogs, making mistakes common. In addition, products for different sized dogs, containing different doses are also sold in similar packaging. These practices increase the likelihood of mistakes in product purchase and application.
Due to a significant increase in adverse incidents in 2008, the U.S. Environmental Protection Agency is taking a series of actions to increase the safety of spot-on pesticide products for flea and tick control on cats and dogs. EPA will begin reviewing labels to determine which ones need stronger and clearer labeling statements. EPA will also develop more stringent testing and evaluation requirements for both existing and new products. EPA expects that these steps will help prevent adverse reactions in dogs and cats including skin irritation and redness, vomiting, diarrhea, trembling, appearing depressed, or seizures.
New restrictions will be placed on these products, and pet owners need to carefully read and follow all labeling before exposing their pet to one of these pesticides. These changes are the result of an intensive evaluation of these products.
EPA will consider the following associated with spot-on flea and tick products:
• Requiring manufacturers of spot-on pesticide products to improve labeling, making instructions clearer to prevent product misuse.
• Requiring more precise label instructions to ensure proper dosage per pet weight.
• Requiring clear markings to differentiate between dog and cat products, and disallowing similar brand names for dog and cat products. Similar names may have led to misuse.
• Requiring additional changes for specific products, as needed, based on product-specific evaluations.
• Granting only conditional, time-limited registrations when new products are registered to allow for post-marketing product surveillance. If there are incidents of concern associated with the product, EPA will take appropriate regulatory action.
• Restricting the use of certain inert ingredients that EPA finds may contribute to the incidents.
• Launching a consumer information campaign to explain new label directions and to help users avoid making medication errors.
In addition, to improve the regulatory oversight of pet products, EPA will require more standardized post-market surveillance reporting on adverse effects, require submission of more sales information so the agency can better evaluate incident rates, and bring up to date the scientific data requirements on pre- and post-market testing so they are more in line with the Food and Drug Administration's requirements.
Flea and tick products can be appropriate treatments for protecting pets and public health because fleas and ticks can transmit disease to animals and humans. While most people use the products with no harm to their pets, the agency's analysis determined that smaller dogs tend to be disproportionately affected by some products and that the exposure of cats to some dog products is a concern.
People should carefully follow label directions and monitor their pets for any signs of an adverse reaction after application, particularly when using these products for the first time. Negative reactions in dogs and cats can include drooling, burns, tremors, seizures, or even death.
EPA recommends that owners consult a veterinarian about the best way to protect their pets from fleas and ticks or whether pesticides are needed, especially before using any product on weak, aged, medicated, sick, pregnant or nursing pets, or on pets that have previously shown signs of sensitivity to pesticide products.
EPA is coordinating these actions with Health Canada as Canada also identified similar concerns about the use of spot-on flea and tick products last year, and with the Food and Drug Administration's Center for Veterinary Medicine.
The agency is inviting public comment on how best to implement these new measures. A Federal Register notice announcing the opening of a docket will be published on March 19, 2010. The docket number is EPA-HQ-OPP-2010-0229.
EPA's report on the evaluation of products and incidents is available at: http://www.epa.gov/pesticides/health/petproductseval.html. EPA recommends that veterinarians use the National Pesticide Information Center's Veterinary Pesticide Adverse Effects Portal to report incidents: http://npic.orst.edu/vet.
(Phil Nixon, slightly modified EPA news release; the first four paragraphs of this article were not part of the news release).