Editing Pesticide (section)

==== Measuring exposure to pesticides ====
There are multiple approaches to measuring a person's exposure to pesticides, each of which provides an estimate of an individual's internal dose. Two broad approaches include measuring biomarkers and markers of biological effect.<ref name=":03">{{Cite journal |vauthors=He F |date=1999-09-05 |title=Biological monitoring of exposure to pesticides: current issues |journal=Toxicology Letters |volume=108 |issue=2–3 |pages=277–283 |doi=10.1016/S0378-4274(99)00099-5 |pmid=10511272}}</ref> The former involves taking direct measurement of the parent compound or its metabolites in various types of media: urine, blood, serum. Biomarkers may include a direct measurement of the compound in the body before it's been biotransformed during metabolism. Other suitable biomarkers may include the metabolites of the parent compound after they've been biotransformed during metabolism.<ref name=":03" /> Toxicokinetic data can provide more detailed information on how quickly the compound is metabolized and eliminated from the body, and provide insights into the timing of exposure.

Markers of biological effect provide an estimation of exposure based on cellular activities related to the mechanism of action. For example, many studies investigating exposure to pesticides often involve the quantification of the acetylcholinesterase enzyme at the neural synapse to determine the magnitude of the inhibitory effect of organophosphate and carbamate pesticides.<ref name=":13"/><ref name=":33"/><ref name=":23"/><ref name=":03"/>

Another method of quantifying exposure involves measuring, at the molecular level, the amount of pesticide interacting with the site of action. These methods are more commonly used for occupational exposures where the mechanism of action is better understood, as described by WHO guidelines published in "Biological Monitoring of Chemical Exposure in the Workplace".<ref>{{Cite book |author=((World Health Organization. Office of Occupational Health.)) |title=Biological monitoring of chemical exposure in the workplace: guidelines |date=1996 |publisher=World Health Organization |isbn=978-951-802-158-5 |language=en |url=https://apps.who.int/iris/handle/10665/41856 |hdl=10665/41856}}</ref> Better understanding of how pesticides elicit their toxic effects is needed before this method of exposure assessment can be applied to occupational exposure of agricultural workers.

Alternative methods to assess exposure include questionnaires to discern from participants whether they are experiencing symptoms associated with pesticide poisoning. Self-reported symptoms may include headaches, dizziness, nausea, joint pain, or respiratory symptoms.<ref name=":33"/>

===== Challenges in assessing pesticide exposure =====
Multiple challenges exist in assessing exposure to pesticides in the general population, and many others that are specific to occupational exposures of agricultural workers. Beyond farm workers, estimating exposure to family members and children presents additional challenges, and may occur through "take-home" exposure from pesticide residues collected on clothing or equipment belonging to parent farm workers and inadvertently brought into the home. Children may also be exposed to pesticides prenatally from mothers who are exposed to pesticides during pregnancy.<ref name=":32"/> Characterizing children's exposure resulting from drift of airborne and spray application of pesticides is similarly challenging, yet well documented in developing countries.<ref>{{Cite journal |last1=Wesseling |first1=Catharina |last2=De Joode |first2=Berna Van Wendel |last3=Ruepert |first3=Clemens |last4=León |first4=Catalina |last5=Monge |first5=Patricia |last6=Hermosillo |first6=Hernán |last7=Partanen |first7=Limo J. |date=October 2001|title=Paraquat in Developing Countries |journal=International Journal of Occupational and Environmental Health |volume=7 |issue=4 |pages=275–286 |url=http://www.maneyonline.com/doi/abs/10.1179/oeh.2001.7.4.275 |doi=10.1179/oeh.2001.7.4.275 |pmid=11783857 |issn=1077-3525 |language=en}}</ref> Because of critical development periods of the fetus and newborn children, these non-working populations are more vulnerable to the effects of pesticides, and may be at increased risk of developing neurocognitive effects and impaired development.<ref name=":32"/><ref name=":022"/>

While measuring biomarkers or markers of biological effects may provide more accurate estimates of exposure, collecting these data in the field is often impractical and many methods are not sensitive enough to detect low-level concentrations. Rapid cholinesterase test kits exist to collect blood samples in the field. Conducting large scale assessments of agricultural workers in remote regions of developing countries makes the implementation of these kits a challenge.<ref name=":03"/> The cholinesterase assay is a useful clinical tool to assess individual exposure and acute toxicity. Considerable variability in baseline enzyme activity among individuals makes it difficult to compare field measurements of cholinesterase activity to a [[reference dose]] to determine health risk associated with exposure.<ref name=":03"/> Another challenge in deriving a reference dose is identifying health endpoints that are relevant to exposure. More epidemiological research is needed to identify critical health endpoints, particularly among populations who are occupationally exposed.