Human Safety

To be able to ensure human safety, we first need to understand what the potential risks to human health are when exposed to pesticides. To assess the potential risks, we evaluate both hazard and exposure.

To understand the potential risk of using a specific crop protection product, we need to understand at what exposure level (dose) the chemical can be hazardous (toxicity).

All chemicals can be toxic if the exposure is high enough. Too much sugar can cause nausea, excitation, and an increase in heart rate and too much salt can cause dehydration, elevated blood pressure, and irregular heartbeats. We call this acute or direct toxicity.

The period of time you get exposed to a product also matters. If you eat a lot of sugar each day it might not harm you directly but could cause diseases like diabetes or obesity in the long run. We call this chronic toxicity.

In the same way, it is important to know how and when people might become exposed to pesticides, and in what quantity. We also need to know what effects can be caused by high exposures.

For human safety, pesticides are required by law to undergo more than 50 laboratory studies to assess their toxicity.

Effect Level Testing

Toxicity is assessed by looking at:

• different routes of exposure (oral, skin, and inhalation);
• different lengths of time (1-7 days (acute); 14-90 days (subchronic) and 1-2 years (chronic — the lifespan of test species); and
• different exposure levels 

All studies are designed to look at effects found at different doses (exposure levels). Most studies have a control (no exposure), low, medium, and high doses. The low dose is typically 100 or more times higher than real exposures people may experience from the use of pesticides according to the label instructions, and often shows no effects. This helps us determine a safe level for risk assessment, i.e., the level of exposure (dose) where there will be no adverse effects. 

In order to complete our assessment of risk to human safety, we not only need the hazard (toxicity) information, but we also need to understand human exposure. Humans can be exposed to pesticides through:

• use (mixing/loading and applying pesticides) on the farm, in the garden, or in the home;
• possible residues in drinking water and food or
• from medical use for fungal infections (e.g. athlete’s foot or toenail infections) and pests (e.g. head lice or scabies)

Studies are conducted that monitor exposure to farmworkers, residents, bystanders, and consumers, as well as residues on treated crops, soil, air, and ground or surface water. In addition, many countries monitor food in grocery stores and imported from other countries in efforts to enforce good agricultural practices.

If the predicted concentrations show a potential risk, mitigation measures are mandatory to reduce the exposure. In such a case, models are used to predict the reduction of exposure through changes in labels, requirements in protective equipment, and other stewardship actions. You can learn more about mitigation a few paragraphs below.

Based on the knowledge derived from the toxicology, metabolism, and exposure studies, we derive reference values (e.g. Acceptable Operator Exposure Level (AOEL), Acute Reference Dose (ARfD) and Acceptable Daily Intake (ADI) that are used to conduct human health risk assessments for our products to determine how they can be used safely.

In our assessments, we compare toxicity study information about exposure levels that may cause effects (dose-response) and predicted concentrations people may be exposed to from all possible sources (food, water, air, direct contact during handling of the product). The combination of hazard and exposure informs us about potential risk (remember the shark — the shark is in the deep water, but if you are onshore or in shallow water, your risk of harm is small).

Risk assessment approaches based on regulations can vary from country to country, but at Bayer, we base our assessments on the most robust science-based methods that meet or exceed these standards. All Bayer products must pass our safety standards before we submit them for registration, even in countries where no such regulations are in place. For older products that may have been registered for a long time, we systematically assess over time and mitigate any use that does not meet our current standards. As we continually evolve and improve our standards based on the state of the art of available science, our assessments are part of the lifecycle management of our portfolio of products. 

Two main risk assessments are conducted in human safety to account for people’s most significant routes of exposure: dietary (1) and operator exposure (2). 

If a product passes the human safety assessment, it can be used without unacceptable risk. However, this does not mean it can be used in any possible way - the human safety assessment also indicates the conditions of safe use. Typical conditions would be that the product must only be applied at certain times (e.g. minimum days before harvest), only at certain maximum rates, or only in a certain agricultural context. Therefore, after completion of the safety assessment, there are several more steps to define these use conditions and to make sure that they are fulfilled in practice.