Pesticides include insecticides, herbicides, fungicides, rodenticides and antimicrobials. For the purposes of this post, we’ll look at the effects of the most ubiquitous – the insecticides and herbicides – which contain both active and inert ingredients.
Active ingredients are there to kill the pest(s) and plants and the inert ingredients are there to help the active ingredients to work more effectively. Inert ingredients, which don’t have to appear on the labelling, can include solvents that may be toxic if inhaled or absorbed by the skin.
Pesticide exposure can cause a range of neurological health effects; symptoms are often very subtle and may not be recognised by doctors for what they are. Effects range from short-term impacts such as headaches and nausea to chronic impacts like cancer, reproductive harm, and endocrine disruption.
Acute impacts include nerve, skin and eye irritation and damage, headaches, dizziness, nausea, fatigue, and systemic poisoning. Acute poisoning can sometimes be fatal.
Adverse health effects include memory loss, loss of coordination, reduced speed of response to stimuli, reduced visual ability, altered or uncontrollable mood and general behaviour, reduced motor skills, asthma, allergies, and hypersensitivity, cancer, hormone disruption, and problems with reproduction and foetal development.
Animal studies link many of these conditions with prenatal exposure to hormone disrupting substances:
- Reproductive cancers
- Hypospadias, undescended testes and other birth defects
- Precocious puberty in girls
- Reduced sperm counts and other fertility problems
Children and pesticide exposure
Children are at greater risk from exposure to pesticides because of their small size: relative to their size, children eat, drink, and breathe more than adults. Even very low levels of exposure during development may have adverse health effects, such as ill health and autism spectrum disorders (ASD). Children’s bodies and organs are growing rapidly, which also makes them more susceptible; in fact, children may be exposed to pesticides even while in utero. Later, playing in the grass and on carpets, putting objects into their mouth, etc, means their exposure to toxic pesticides carries on.
Multiple Chemical Sensitivity (MCS) or Environmental Illness
MCS/Environmental Illness is a medical condition characterised by the body’s inability to tolerate relatively low exposure to chemicals; exposure to pesticides is a common way for individuals to develop MCS. Once the condition is present, symptoms, including cardiovascular problems, depression, muscle and joint pains and more, are easily started off again. Over time, individuals suffering from MCS will begin to react adversely to substances that formerly did not affect them.
Pesticides and cancers
Pesticides can cause many types of cancer in humans. Some of the most prevalent forms include leukaemia, non-Hodgkin’s lymphoma, brain, bone, breast, ovarian, prostate, testicular and liver cancers.
Studies show worrying trends. For example:
- Children who live in homes where their parents use pesticides are twice as likely to develop brain cancer than those where no pesticides are used
- American farmers, who in most respects are healthier than the population at large, showed worrying incidences of leukaemia, Hodgkin’s disease, non-Hodgkin’s lymphoma, and many other forms of cancer
Insecticides and their effects
Organochlorides: Acute ingestion of organochlorine insecticides can cause a loss of sensation around the mouth, hypersensitivity to light, sound and touch, dizziness, tremors, nausea, vomiting, nervousness, and confusion.
Organophosphates and carbamates: Acute exposure causes signs and symptoms of excess acetylcholine, such as increased salivation and perspiration, narrowing of the pupils, nausea, diarrhoea, decrease in blood pressure, muscle weakness and fatigue. (These symptoms usually decline within days after exposure ends as acetylcholine levels return to normal.) Some organophosphates also have a delayed neurological reaction characterised by muscle weakness in the legs and arms.
Pyrethroids: Pyrethroids are organic compounds similar to the natural pyrethrins produced by the flowers of pyrethrums. Pyrethroids now constitute the majority of commercial household insecticides as they were found to be a ‘safer’ alternative to organophosphates. However, they can cause hyper-excitation, aggressiveness, lack of coordination, whole-body tremors, and seizures for up to 24 hours. Pyrethroids can cause an allergic skin response, and some may cause cancer or affect reproduction, development, and the endocrine system.
Herbicides and their effects
Herbicides are generally less toxic to mammals than insecticides as most herbicides are systemic, interfering with plant hormones, enzymes and cells. However, some herbicides may cause cancer, reproductive and developmental problems, or affect the endocrine system.
The worst herbicides (banned now, but still around) are those containing dioxin (TCDD) exposure to which can give rise to birth defects, cancers, liver disease, and other illness.
Only certain herbicides are allowed to be used near water because they break down and do not negatively affect the ecosystem, but soil erosion can cause herbicides to run off into water bodies, where the herbicide ends up in the human water supply and may also affect wildlife.
Roundup, one of the most common herbicides, contains atrazine; this has been found to interfere with enzyme production and steroid synthesis. It has been implicated in inhibiting the development of human placenta cells, causing miscarriage. Atrazine can also cause abnormal birth rate, which has caused Europe to ban the herbicide.
Picture by Austin Valley