Session 3: Modelling Cumulative Exposures

Cumulative Exposure: What we know and what we need to know
Arpad Szarka: Syngenta Crop Protection

Arpad Szarka


Syngenta Crop Protection


We are well aware that we are exposed to not just one, but many chemicals at a time.

This is known as cumulative exposure: simultaneous exposure to multiple chemicals.

However, our capacity to estimate cumulative exposure is still being developed. Consistent with RISK21 principles, exposure assessment is a critical early step in understanding human health risks.

However, the variability in exposure estimates can range from one order of magnitude in data-rich situations or several orders of magnitude where there is a lack of data or only rudimentary data availability.

Furthermore, most data is collected on single chemicals and co-exposure is not necessarily considered. Recognizing that our reality is that we are exposed to many chemicals at a time, we need become better at estimating the cumulative exposures to various chemicals.

Lessons can be learned from agricultural risk assessments, which are typically data rich. Individual pesticide exposures to workers and individuals in residential scenarios are well documented in, for example, databases developed by the Agricultural Reentry Task Force (ARTF), the Outdoor Residential Exposure Task Force (ORETF), and Agricultural Handlers Exposure Task Force (AHETF).

Other databases, such as USDA’s Pesticide Data Program (PDP) and the Residential Joint Venture (REJV) contain information on simultaneous exposures to multiple pesticides.

Computer models such as CARES and SHEDS will be briefly described. These software tools utilize these databases to reduce uncertainty in exposure estimation and give us a better capacity to estimate cumulative exposures.