Longitudinal assessment of occupational exposures to the organophosphorous insecticides chlorpyrifos and profenofos in Egyptian cotton field workers

Abstract

Chlorpyrifos (CPF) and profenofos (PFF) are organophosphorus (OP) insecticides that are applied seasonally in Egypt to cotton fields. Urinary trichloro-2-pyridinol (TCPy), a specific CPF metabolite, and 4-bromo-2-chlorophenol (BCP), a specific PFF metabolite, are biomarkers of exposure, while inhibition of blood butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) activities are effect biomarkers that may be associated with neurotoxicity. Urinary TCPy and BCP and blood BChE and AChE activities were measured in 37 adult Egyptian Ministry of Agriculture workers during and after 9-17 consecutive days of CPF application followed by an application of PFF (9-11 days), and a second CPF application (5 days) in 2008. During the OP applications, urinary TCPy and BCP levels were significantly higher than baseline levels, remained elevated following the application periods, and were associated with an exposure related inhibition of blood BChE and AChE. Analysis of blood AChE levels before and after the PFF application period suggests that individual workers with peak BCP levels greater than 1000 μg/g creatinine exhibited further inhibition of blood AChE with PFF application, demonstrating that PFF exposure had a negative impact on AChE activity in this highly exposed worker population. While large interindividual differences in exposure were observed throughout this longitudinal study (peak urinary BCP and peak TCPy levels for individuals ranging from 13.4 to 8,052 and 16.4 to 30,107 μg/g creatinine, respectively), these urinary biomarkers were highly correlated within workers (r= 0.75, p<0.001). This suggests that the relative exposures to CPF and PFF were highly correlated for a given worker. The variable exposures between job classification and work site suggest that job title and work location should not be used as the sole basis for categorizing OP exposures when assessing neurobehavioral and other health outcomes in Egyptian cotton field workers. Together, these findings will be important in educating the Egyptian insecticide application workers in order to encourage the development and implementation of work practices and personal protective equipment to reduce their exposure to CPF and PFF.

Spatial learning impairment in prepubertal guinea pigs prenatally exposed to the organophosphorus pesticide chlorpyrifos: Toxicological implications

“…At any time workers enrolled in these programs present RBC AChE activity at or below 70% of their baselines, they are removed from OP pesticide handling until their RBC AChE activity is within 20% of their personal baseline. However, this is not common practice within the U.S. or worldwide and evidence exists that RBC AChE activity can be reduced by as much as 40–80% from baseline in workers who otherwise present no overt clinical sign or symptom of OP intoxication (Ames et al, 1989; Farahat et al, 2011; Singleton et al, 2015). Thus, based on measurements of RBC AChE, the CPF dose regimen the guinea pigs were subjected to in the present study translates to levels relevant to occupational exposure of people who handle OP pesticides throughout the world.…”

Environmental Health Research in Africa: Important Progress and Promising Opportunities

“…Pesticide applicators and farm workers (including adolescent and child workers) exposed to these compounds exhibit neurological/ neurobehavioral symptoms, deficits in neurobehavior performance tests, and neuromuscular disorders. These symptoms are often associated with greater inhibition of serum BChE and acetylcholinesterase activity, effect biomarkers often associated with neurotoxicity and cumulative TCPy, which is a biomarker of the organophosphorus pesticide chlorpyrifos (Sosan et al, 2010;Khan et al, 2014;Rohlman et al, 2014;Singleton et al, 2015;Manyilizu et al, 2016;Rohlman et al, 2016;Ismail et al, 2017b;Negatu et al, 2018). Some evidence for possible neurodevelopmental effects related to DDT in children has also been suggested (Osunkentan and Evans, 2015).…”

“…Many of the reviewed studies evaluated chronic pesticide exposure and alteration in serum enzymes associated with detoxification of pesticides, particularly inhibition of butyryl cholinesterase activity (Araoud et al, 2010;Araoud et al, 2011;Araoud et al, 2012). Biomarkers of exposures to the organophosphorus pesticides, chlorpyrifos (CPF) and Profenofos (PFF), were evaluated in some studies by measuring urinary levels of 3,5,6-trichloro-2-pyridinol (TCPy), a specific CPF metabolite and 4-bromo-2-chlorophenol (BCP), a specific PFF metabolite (Singleton et al, 2015). Inhibition of blood butyryl cholinesterase (BChE) and acetylcholinesterase (AChE) activities are effect biomarkers that were also evaluated in several of the reviewed studies Khan et al, 2014;Rohlman et al, 2014;Singleton et al, 2015;Rohlman et al, 2016;Ismail et al, 2017a;Ismail et al, 2017b).…”

Perceptions, Practices, and Mother’s Willingness to Provide Meconium for Use in the Assessment of Environmental Exposures among Children in Mukono and Pallisa Districts, Uganda

“…Among the human tissues are blood [1,2], urine [3,4], breast milk [5,6], and meconium [7][8][9]. Meconium testing provides a more sensitive matrix to measure fetal exposure to toxicants, due to its ability to cover a longer period of exposure than other matrices such as infant hair and cord blood [10].…”