Vector-borne disease vs chemicals in bug spray: Weighing the risks

By Michelle M. Forman, senior media specialist, APHL

Vector-borne disease vs chemicals in bug spray: Weighing the risks | www.aphl.orgWith hot and humid weather comes news of diseases spread by mosquitos and ticks, while we also hear of concerns around the bug sprays we’re supposed to use to protect ourselves. What exactly are people supposed to do? Which pieces of information should you believe? How are you to decide the best way to protect yourself and our family from bites, disease AND harmful chemicals all at the same time? At this point, locking yourself inside until winter might seem like the only option.

Not to worry. The important thing is to consider whether the risks associated with each vector-borne disease are more or less worrisome than the risks associated with the chemicals found in bug sprays. Here is our breakdown of those risks.

While vector-borne diseases refer to illnesses transmitted by many tours of insects, we’re going to focus on mosquitoes and ticks here.

Note the severity of each vector-borne disease and impacts of applications described below may differ based on individual conditions such as age, predetermined health status, access to healthcare, etc. If you have any questions or concerns, please speak with your physician.

Mosquito-Borne Diseases

West Nile virus (WNV)WNV is found in all 48 contiguous states. The number of cases annually varies. 2012 was the deadliest year with 286 deaths.

  • The bad news: Those who show symptoms will typically have headache, body aches, joint pain, vomiting, diarrhea and/or rash within about a week of the infectious bite. In some cases, fatigue and weakness can last for months. In more severe cases, people can even develop neurologic conditions like encephalitis or meningitis. About 10% of those people will die. There are no medications or treatments for WNV aside from pain medication to reduce fever or relieve some of the symptoms. Those experiencing the most severe symptoms may be hospitalized.
  • The good news: Not every person bitten by an infected mosquito will show symptoms.

Eastern equine encephalitis virus (EEEV) – In the United States, an average of six human cases of EEE are reported annually. Cases mostly occur in the Atlantic and Gulf Coast states, although there have been some cases in the Great Lakes region as well.

  • The bad news:  EEE can be very serious. Severe cases will experience headache, high fever, chills and vomiting which could progress into disorientation, seizures, encephalitis and coma. Approximately one-third of patients who develop EEE die, and many of those who survive have mild to severe brain damage. Some of the long-term effects can cause death years later. There is no specific antiviral treatment for EEE; people showing symptoms should see their healthcare provider who can determine if supportive treatment is necessary and available.
  • The good news: Most cases will not show any symptoms, and only about 4-5% of EEEV cases become EEE.

Chikungunya – While there have only been four reported cases of locally acquired chikungunya in the US, experts are concerned because the disease spreads so rapidly. Chikungunya first reached the Caribbean in December 2013 and by March 2014 there were 15,000 reported cases.Chikungunya has now been identified in nearly 40 countries in Asia, Africa, Europe and, most recently, the Americas.

  • The bad news:  Nearly everyone who is bitten by an infected mosquito will develop fever and joint pain; other symptoms may also include headache, muscle pain, joint swelling or rash. The joint pain is often very debilitating, but usually lasts for a few days or possibly weeks. In some cases joint pain may continue for months or years. There have been some reports of lasting gastrointestinal, eye, neurological and heart complications. There is no treatment for chikungunya aside from over the counter pain medication to reduce discomfort.
  • The good news: Most people fully recover.

Dengue virus – According to CDC, there are over 100 million cases of dengue worldwide each year. It is a leading cause of death in many tropical areas of the world. While it is not typically found in the continental US, dengue is endemic in Puerto Rico and many parts of Latin America, Southeast Asia and the Pacific Islands where Americans vacation.

  • The bad news: Typical symptoms include high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding (e.g., nose or gums bleed, easy bruising). Dengue hemorrhagic fever, a more severe form of dengue virus, is characterized by a fever that lasts from 2 to 7 days. It can be fatal if unrecognized and not properly treated in a timely manner.
  • The good news: Early detection and treatment will lower the rate of fatality to below 1%.

Tick-Borne Diseases

Lyme – According to CDC, Lyme disease is the most commonly reported vector-borne illness in the United States with over 20,000 cases annually. However it does not occur nationwide, but tends to be heavily concentrated in the northeast and upper Midwest.

  • The bad news: Bulls-eye rash occurs in 70-80% of infected people. Other symptoms include fatigue, chills, fever, headache, muscle and joint aches, and swollen lymph nodes. 10-20% of cases treated with antibiotics have muscle and joint pains, cognitive defects, sleep disturbance, or fatigue that lasts months or even years. In extremely rare cases (1% of cases), Lyme disease bacteria can enter the heart tissue causing Lyme carditis which can be fatal.
  • The good news: Patients can be treated with antibiotics and the prognosis is best when treatment begins early.

Rocky Mountain Spotted Fever – Spread through the bite of an infected tick, Rocky Mountain Spotted Fever occurs throughout the US.

  • The bad news: Symptoms typically begin with a sudden fever and headache, but many patients will eventually develop a rash, stomach pain, nausea, fatigue or muscle aches. (Not all cases develop every symptom.)  Severe cases can lead to life-long complications such as neurological problems and internal organ damage.  In extremely rare cases (less than 1% of cases), Rocky Mountain Spotted Fever can be fatal. Diagnosis can be difficult as the symptoms can resemble other conditions, and diagnostic tests looking for antibodies are often negative within the first 7-10 days. Treatment is most successful if started in the first five days.
  • The good news: While the number of cases has been higher than usual, the fatality rate is at an all-time low.

Bug Spray – These chemicals have been determined to be the most effective in preventing mosquito and tick bites:

DEET

  • The bad news: DEET has been linked to various health risks such as skin irritation, eye irritation and even neurological damage. But those cases are very rare, and many studies have found the connection between DEET and serious health risks to be inconclusive.
  • The good news: DEET is widely regarded as the most effective chemical in personal bug repellant. The stuff works! Better yet, using DEET with caution appears to significantly limit any serve risks; in fact, many now feel that DEET is safer than once believed. By using lower concentrations (10-30% for children), only using when it is necessary and following the instructions on the label the benefits of DEET far outweigh any risks.

Picaridin

  • The bad news: Picaridin has not been as effective for as long a period of time as DEET in some studies. It also does not protect against all species of mosquitoes. Picaridin is also a relative new kid on the block, so surveillance data is still lacking.
  • The good news: Picaridin is structurally made from the chemicals in pepper, so it is more natural than DEET. It is less likely to irritate skin, doesn’t have the same strong odor as DEET and seems to have a safer profile than DEET.

IR3535

  • The bad news: Concentrations of less than 10% were considered ineffective. IR3535 can be very irritating to the eyes, and has been shown to damage plastics.
  • The good news: IR3535 has been used in Europe for over 20 years. It has a safer profile than its competitors.

Oil of lemon eucalyptus and para-menthane-diol (PMD – synthetic concentration of lemon eucalyptus oil)

  • The bad news: Oil of lemon eucalyptus enhanced with PMD is not recommended for children under the age of 3. It can be irritating to the lungs and cause possible allergic reactions. Protection time seems to be less than DEET.
  • The good news: Higher concentrations seem to be as effective as 15-20% DEET. While lower concentrations will reduce the risk of allergic reaction and lung irritation, they are considerably less effective in repelling mosquitoes and ticks. For those insisting on a botanical bug spray, this is considered the best option.

So what’s the answer to our initial questions? Well, it isn’t really that easy. There is no one right answer for every person in every situation. Vector-borne diseases present a serious health risk that should be avoided. DEET is the most effective chemical for repelling insects available, and studies have shown that risk is low and effectiveness is still high when using concentrations under 30%. The other chemicals listed above may also be reasonable options for you and your family.

Our recommendation: The benefits associated with the chemicals far outweigh the risks. Wearing long pants and sleeves, wearing a hat and eliminating standing water will also help decrease the risk of mosquitoes and ticks. But the best way to avoid vector-borne diseases is to use bug spray when you are in an area with a high number of mosquitoes and ticks.

Measuring Household Dust for Potentially Dangerous Chemicals

This blog post is part of a biomonitoring series.

Can analyzing our household or workplace dust help scientists predict the levels of potentially dangerous chemicals inside our bodies?

In a world where furniture, carpets, curtains and electronics are treated with potent flame-retardant chemicals, we are exposed continuously to novel chemical substances upon which little research has been conducted. The use of flame retardants has become necessary due to changing types of materials used in our household goods.

Measuring Household Dust for Potentially Dangerous Chemicals | www.aphlblog.org

“Think of your living room and all the synthetic materials used in the furnishings and curtains,” said Myrto Petreas, PhD, MPH, from the California Department of Toxic Substances Control. “Now compare that to what was in your grandmother’s living room. Her furniture was probably made with horsehair and wool, and was inherently not prone to fire. With synthetic fabric, there is more fire danger.”

The concern about flame retardants, she said, is that very little is known about these chemicals or what levels, if any, are safe for humans.

Around the time polychlorinated biphenyls, more commonly known as PCBs, were banned in 1979 due to human carcinogenic effects, chemists began creating new flame-retardant chemicals. Fifteen years ago, Petreas and her staff encountered one of the newer ones for the first time. “We were measuring chemicals in a study of breast cancer and looking at the body fat, levels of PCBs, etc. I went to a meeting in Sweden in 1998, where a researcher presented on these new chemicals, PBDEs (polybrominated diphenyl ethers), found in high levels in human breast milk. Back at the lab, I wondered, ‘Can we see it here?’ The levels were so high, I thought it was a mistake.”

Pausing, Petreas added, “The levels are 30 times higher in California now than they were in Sweden then.”

While researchers do not know for sure that the brominated flame retardants, especially the PBDEs, are carcinogens, they are structurally similar to the banned PCBs. They also assimilate into our fat. PCBs, although banned 35 years ago, are still found commonly in people, said Petreas, “because they are in the food web now.” Banning a chemical cannot eradicate it from the population, she explained, but “PBDEs are placed on purpose in our products. We are exposed through dust more than diet. After they are banned, 20 years from now, those PBDEs will be in the food web too, in birds and cows. They stay a long time in the body.”

PBDEs are endocrine disruptors that compete with the thyroid’s hormones, potentially affecting development and cognitive abilities. “In animals,” said Petreas, “they are carcinogens; in humans, we can now look and see but do not have the answers yet.”

The question about whether chemical levels found in dust can help predict the levels in our bodies is an interesting one to biomonitoring scientists who study chemical levels in the human body. “What you see in the dust takes many steps to reach your body,” said Petreas. Just because the chemical is in the air or dust does not mean that your body will absorb it. Also, it is possible that chemicals may be dangerous in combinations rather than alone. Genetics also likely influence susceptibility. Biomonitoring is a sufficiently new science that many questions remain unanswered.

However, it is feasible that scientists could get a good idea of exposure merely by studying the contents of a household’s vacuum cleaner.

Petreas’ lab has worked on two dust studies. One, the California Childhood Leukemia Study, with UC Berkeley, is looking for correlations between childhood leukemia and chemical exposures found in the home. The study is not complete but after looking at the dust samples, Petreas said, “we have seen differences among homes and geography. There is a socio-economic factor: there are higher levels of PBDEs in house dust among lower income households and people of color.”

They also found a high correlation in results from dust tests repeated 3-8 years apart on the same home, showing that the chemical levels were not declining much over time.

The second study, the Firehouse Dust Study that compared levels of pollutants in the blood of firefighters and in the dust of the firehouses, was a side-study of the Firefighters’ Occupational Exposures (FOX) study, conducted by Biomonitoring California with UC Irvine.

“In this pilot study, we tested the blood and urine of 99 men and 2 women,” said Petreas. “We had questionnaires about their work: do they work with forest fires or structural fires? What kind of protective gear do they have and is it used? Later, we wanted to combine the environmental measure with this earlier biological measure. We took samples of dust from the station’s vacuum cleaners. This gives an overall integrated measurement to what the firefighters have been exposed to over time in the firehouse.”

They discovered, perhaps unsurprisingly, that firefighters did have much higher levels of flame retardants in their blood than an average person. Researchers are still trying to identify the main sources of exposure.

Actually, PBDE levels in Californians are higher than in most Americans, largely because of the state’s unique flammability requirements. Petreas pointed out that because the California market is so large, many corporations are designing products to meet the state’s stringent flammability standards and then selling them across North America. As a result, PBDE levels in North Americans are much higher than in Europeans or Asians.

“[Researchers] are always a few levels behind the marketplace,” said Petreas. “We measure the PBDEs now, but already there are different chemicals being used and we don’t know what they are. We can see these chemicals in our samples, but we haven’t studied them yet.”

An important factor in launching these studies has been the creation of Biomonitoring California, a legislatively mandated program that aims to determine baseline levels of environmental contaminants in Californians, study chemical trends over time, and advise regulatory programs. Biomonitoring California is a collaborative effort between the California Department of Public Health, the Office of Environmental Health Hazard Assessment, and the Department of Toxic Substances Control.

“What else is out there that we don’t know about and haven’t looked for?” Petreas asked, echoing a concern that led to the creation of Biomonitoring California.

To reduce exposure to potentially dangerous chemicals, whether from dust or other sources, Petreas said, “Wash your hands before you eat. Just like your mother told you. Never eat at your computer. Leave your shoes outside. These things help with most public health concerns, whether avian flu or chemicals.”

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Without biomonitoring, public health practitioners face challenges in understanding whether environmental contaminants are actually being absorbed into people’s bodies. Given improvements in technology, the capabilities and expertise that exist in public health laboratories, and the increasing demand from the public for more information about chemical exposures, biomonitoring is poised to become an integral component of public health practice.

To learn more about biomonitoring, check out some of APHL’s Biomonitoring Resources:

Stay tuned for our soon-to-be-unveiled Meeting Community Needs page and of course, let us know if you have any feedback or suggestions.