Pesticides tend to be a problem more so within the growing of food crops, which have often been genetically modified to withstand the effects of herbicides and have been bred for features such as heavy crops, fast growth and optimum storage conditions, and not for resilience within a natural environment.  Herbs, on the other hand, tend to not be subject to this kind of selection. However, in recent times, use of pesticides, herbicides, insecticides and fungicides has become so widespread and prolific, that pollution into surrounding water and land has become an ever-increasing issue. This means the impact of these chemicals is detectable far beyond the boundaries of the fields on which they were applied. This has major implications for the environment. The intensification of agriculture and in particular the recurrent use of chemical fertilizers and pesticides is the primary driver for the loss of biodiversity of birds, insects, mammals and aquatic organisms in streams. With the current trends, it is estimated that we will lose 40% of the world’s insect species over the next few decades (2).

The contamination with pesticides through these indirect sources is called non-point contamination, a phenomenon, which is more and more detectable within culinary and medicinal herbs commonly harvested from non-organic as well as organic sources (3,4,5,6). Although organically cultivated crops show far less residues (4), and generally must be tested for pesticide residues, to maintain their organic certification. While some medicinal herbs tend to be sourced from cultivation, many herbs are exclusively wild harvested. However, wild harvest does not guarantee that the final product will be free from pesticides. Often, wild-collection sites are close to agricultural areas and pesticides find their ways into the local ecosystem. One study compared samples from cultivation and wild-collection and found that the wild-collection sources had higher levels of contaminants (3). 

One study analysed 47 different ginseng products including both Asian ginseng (Panax ginseng) and American ginseng (P. quinquefolius) to determine the content of pesticides and toxic heavy metals (5). They found that 24 samples (80%) contained pesticides above the detection limit and 13 samples (43%) did not comply with the maximum residue limits (MRL) for various pesticides imposed for botanical extracts. The levels were up to 55 times their maximum residue limits — set up to limit exposure to harmful rates of pesticides (5). Within Europe, Poland is perhaps the country with the largest amount of herbal cultivation. Around 20,000 farms, on ca. 30,000 hectares, produce around 50,000 tonnes of herbs from crops and 10,000 tonnes of herbs from wild collection. Here too pesticide levels have been detected within samples taken from herbs, raising concern for our medicinal herbs (6). 

While the presence of these chemicals might not indicate that pesticides were used in their production (as they are more often used in the production of food crops, surrounding the areas where the herbs grow) it is still concerning regarding the environmental impact this pollution has. But it should also concern herbalists, who wish to prescribe medicinal products, from a healthcare perspective. Insecticides, fungicides, herbicides may all affect our health in various ways. And while individual safety levels have been set for the environment, food and drink products, they do not consider the “cocktail” effect, that happens, through the combination of multiple pesticides. Various pesticide combinations can have additive effects, the various chemicals may interact with one another and lead to synergistic negative effects on human health (7).

Pesticides can affect our health through altering our gut microbiota composition and their metabolites and impact the intestinal mucosa and cell lining. All these changes can further negatively impact the health of those consuming these pesticides (8,9,10). Various health conditions are linked to increase exposure of pesticides, including Alzheimer’s, Parkinson’s disease, breast, bladder, colon, liver and brain cancer, asthma, diabetes, allergic reactions and leukaemia (11). Additionally, pesticides can cross the placental barrier (12), and prenatal exposure to pesticides has been linked to increase in birth defects as well as cognitive effects such as lowered IQ, perceptual reasoning and poorer memory (11). 

While some companies may test for artificial pesticide residue on herbs on a voluntary basis, all organically certified herbs must be tested for any contamination, giving a greater reassurance of herbs with minimal pesticide levels (a maximum of 0.01mg/kg). Choosing organic herbs means a lower risk of contamination with artificial pesticides for the herbs. But it also means that the land on which the herbs grow on will be protected from direct exposure to artificial pesticides, protecting the wildlife in that area. This applies to wild-harvested, as well as cultivated sources. To protect the health of the ecosystem is to protect the health of those in relationship with the ecosystem, no matter how far away these may be. 

A caveat: While artificial pesticides are banned with organic certified crops, some organic pesticides are allowed, to make things more complicated, there are various organic standards, some more or less rigorous. It is best to familiarise oneself with the different relevant standards. However, to do this here, would go beyond the scope of this article. Overall, it is evident that organic production relies on less pesticide use and organic products are less likely to contain concerning levels of pesticides. Both beneficial to environment and humans alike.