Pesticide fumigation is employed to protect against insects, fungi or weeds. Many chemicals that are used target the nervous system of insects. Such pesticides may also be neurotoxic to the human brain. Therefore, there have been concerns regarding the adverse effects of fumigation to fetal brain development (Bjørling-Poulsen et al., 2008).
Fumigating with pesticide sprays during pregnancy is not safe. Insecticides contain chemicals that attack the nervous system of insects that cause them to die. They can also attack non-target species, including humans, and can lead to neurotoxicity. Any pesticide exposure in the womb, when the fetal nervous system is rapidly developing, should be avoided.Jesmarie Macapagal, RN, MD, DPPS
This article will talk about what fumigation is, followed by the concerns about fumigating while pregnant. Next, it will discuss the evidences regarding the risks of fumigation and pesticide use during pregnancy. It will also touch on the subject of natural insecticides. Lastly, ways to minimize exposure to unavoidable fumigation will be given.
What is Fumigation?
Fumigation is the application of gas or smoke for the purpose of disinfection. It is a technique where a fumigant (chemical) is used at a specific temperature and pressure to exist in a gaseous state.
Fumigation is also a method of pest control that fills an area with gaseous insecticides to poison the pests. This process may be utilized to control pests in agriculture, in buildings, or at home to get rid of infestations by insects like termites or cockroaches.
The length of time for the fumigation process varies depending on the size of the area to be fumigated, the type of pests to be removed, as well as the extent of the infestation – Meaning, removal of rodents like squirrels involves entirely different fumigant than termites and cockroaches. After fumigating for the designated amount of time, the chemicals are then allowed to escape. The process of fumigation can be hazardous to the people living near or working in the area.
Concerns Regarding Fumigation During Pregnancy
Pesticides are widely used in agriculture, to increase yields and maintain the crops, as well as in homes and gardens (Bjørling-Poulsen et al., 2008). There is widespread residential pesticide use in the United States (Whyatt et al., 2002) and general pesticide use in the world (Mostafalou & Abdollahi, 2013).
In 2002, Whyatt et al. investigated 72 women during their third trimester of pregnancy to determine their exposure to household pesticides. 85 percent of the respondents reported that pest control measures were used in their homes, with 35 percent using fumigation techniques, and 45 percent using fumigation more than once a month.
All of the women in the study had detectable levels of exposure to organophosphate, chlorpyrifos and carbamate insecticides, as well as the fungicide o-phenylphenol. Also detected at lower concentrations were exposure to other insecticides, including pyrethroids, pyrethrins, organochlorines, and chlordane. 30 percent of the women had detectable levels of all of the eight mentioned pesticides (Whyatt et al., 2002).
Experimental studies suggest that many of the pesticides currently used, including organophosphates, carbamates, pyrethroids, carbamates, and chlorophenoxy herbicides, can all cause neurodevelopmental toxicity (Bjørling-Poulsen et al., 2008).
Pyrethroid pesticides are the most widely used in the household due to their relatively low toxicity to mammals (Soderlund et al., 2002). Methyl bromide is a fungicide used in fumigation often in strawberry cultivation areas. It is of concern for residents who live near these agricultural sites because of the pesticide’s toxicity and potential for drift (Gemmill et al., 2013).
There is extensive research done in relation to pesticide exposure and increased rates of chronic diseases, including different kinds of cancers, neurodegenerative disorders, birth defects and reproductive disorders (Mostafalou & Abdollahi, 2013). Despite the advantages of pesticide application, such as protection of crops and against diseases brought about by insect vectors, there are also pressing concerns about the potential toxic effects of pesticides to humans (Richardson et al., 2019), specifically to babies in the womb.
Given that the molecular targets of pesticides are often shared between their target pests as well as non-target species, they have been suspected of causing neurotoxicity to humans (Richardson et al., 2019). The negative effects posed by pesticide fumigation on brain development can be severe and irreversible. The consequences of any inhibition or delay in proper neurologic development during the prenatal period cannot be repaired later in life, and thus, may become permanent (Bjørling-Poulsen et al., 2008).
Prevention of exposure should be a priority during pregnancy. Precautionary action should be undertaken to protect fetal brain development and prevent neurodevelopmental disorders. These include “learning disabilities, attention deficit hyperactivity disorder (ADHD), autism spectrum disorders, developmental delays, and emotional and behavioral problems” (Bjørling-Poulsen et al., 2008).
Therefore, it is advisable that women avoid pesticide exposure throughout the duration of pregnancy (Greenop et al., 2013).
Risks of Pesticide Exposure During Pregnancy
Lower Birth Weight
Two studies both reported a significant reduction in birth weight associated with prenatal exposure to pyrethroid insecticides (Ding et al., 2015) and maternal exposure during the first or second trimester of pregnancy (Hanke et al., 2003).
In 2013, Gemmill et al. concluded that residential proximity within 5 kilometers to agricultural methyl bromide fumigation use during the second trimester of pregnancy was associated with restricted fetal growth, in terms of reductions in birth weight, birth length and head circumference.
Meanwhile, in 2020, Matsuki et al. noted significant associations between fumigation with insecticides and decreased birth weight, and exposure to pyrethroid pesticides (mosquito coils or mats) and decreased neonatal length.
However, the potential effect of insecticides on fetal growth remains unclear, as there are also some studies that found no association between maternal exposure to pesticides and birth weight in babies (Matsuki et al., 2020).
In spite of this fact, those studies that failed to support an association with birth weight found instead a link between pesticide exposure and the following:
- A slight decrease in the duration of pregnancy, with exposed women giving birth half a week earlier on average (Dabrowski et al., 2003)
- Decreased head circumference, which could be predictive of reduced cognitive ability (Berkowitz et al., 2004)
In 2005, Young et al. observed a significant association between exposure with organophosphate pesticide in utero and an increase in the number of abnormal reflexes in infants. Similarly, in 2007, Engel et al. noted a 2.24-fold increase in the number of abnormal reflexes in newborns who were exposed prenatally with organophosphate pesticides. These abnormal primitive reflexes could be a vital marker of compromised neurologic integrity.
In 2006, Rauh et al. investigated the effect on neurodevelopment and behavior in children exposed to chlorpyrifos during pregnancy. This study revealed that children who were highly exposed to chlorpyrifos prenatally scored lower on the Bayley Psychomotor Development Index (PDI) and the Bayley Mental Development Index (MDI) at 3 years old by 6.5 and 3.3 points, respectively.
In addition, children exposed to higher levels of chlorpyrifos were found to be more likely to experience problems with attention, attention deficit hyperactivity disorder (ADHD), and pervasive developmental disorder at 3 years of age, as well as PDI and MDI delays. The proportion of children with delays in the high-exposure group, were 5 times greater for the PDI and 2.4 times greater for the MDI, compared to those in the low-exposure group (Rauh et al., 2006).
In 2017, Gunier et al. observed an association between maternal exposure to chloropicrin fumigation within 3 kilometers and reduced processing speed in their children 7 years of age, while methyl bromide fumigation within 3 kilometers during pregnancy was associated with both lower processing speed and lower full-scale intelligence quotient (IQ) in their children of the same age group.
Childhood Cancer Development
Prenatal exposure to pesticides may also be associated with the development of cancer. Household pesticide exposures were examined in the Northern California Childhood Leukemia Study and their findings suggest that exposure to insecticides early in life was a significant risk factor for the development of childhood leukemia, with the highest risk being exposure during pregnancy. In addition, a more frequent exposure was also seen to lead to greater risk (Ma et al., 2002).
In 2013, Greenop et al. documented elevated risks for low- and high-grade gliomas in children who had a history of prenatal home pesticide exposure. Also in 2013, Ferreira et al. demonstrated that the use of pesticides during pregnancy was associated with the development of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) in children less than 2 years of age. Maternal exposure to permethrin was found to have higher risk estimates for children aged 0 to 11 months.
Findings from the case-control studies in the Childhood Leukemia International Consortium (CLIC) showed that increased odds of both ALL and AML were observed among children who had exposure to any type of pesticide during their mothers’ pregnancy (Bailey et al, 2015).
In 2018, Hyland et al. observed that maternal insecticide use in the home during pregnancy was associated with higher odds of development of ALL among boys, with an increased frequency of insecticide use also increasing the odds of ALL among boys and girls combined. Even pesticide use on farms or companies near the home during pregnancy was also associated with the development of ALL in their offspring.
The majority of the toxins used in pesticides are compounds that are naturally occurring in plants. Though natural insecticides might sound safer, even natural chemicals still have the potential to cause harm to humans, especially to a developing baby.
Natural insecticides, such as pyrethrins, azadirachtin, rotenone, spinosad, and abamectin, contain chemical, mineral and biological materials, including pyrethrum, neem, spinosad, rotenone, abamectin, Bacillus thuringiensis, garlic, cinnamon, pepper, and essential oil products. These can “induce hepatotoxicity, renal toxicity, hematotoxicity, reproductive toxicity, neurotoxicity, and oxidative stress. It can induce mutagenicity, genotoxicity, and carcinogenicity in mammals” (Mossa et al., 2018).
Therefore, there is no natural insecticide that is absolutely free from health risks. The term “natural” does not equate to being “safe” (Mossa et al., 2018). Some natural compounds may be toxic and can cause adverse effects to humans.
Ways to Decrease Exposure from Fumigation
If you are pregnant, and fumigation cannot be helped and is needed for your home, pet, or garden, follow these steps to decrease your risk of exposure:
- Let someone else do the fumigation.
- Leave the area for the time specified in the insecticide package.
- Take all the food, dishes and utensils away from the area before fumigating.
- After fumigation, wash all areas where food is prepared.
- Open the windows and allow good ventilation after fumigation.
- When gardening, pregnant women must wear protective clothing to avoid contact with plants that might have pesticides on them.
Fumigating during pregnancy is not safe. Given the evidences of risks of neurotoxicity and increased likelihood of developing cancers in children exposed in utero, pregnant women should avoid the use of and exposure to pesticides whenever possible.
Even those considered as natural insecticides may not be entirely safe. Precautionary avoidance is the best way to ensure the safety of pregnant women and their unborn babies.
Talk to your most trusted physician to know more information.