Pesticide Exposure Risk Calculator
What this pesticide exposure calculator does
This tool provides a screening-level estimate of your daily oral exposure to a single pesticide from two main sources: drinking water and food. It converts concentrations (how much pesticide is in water or food) and your typical consumption into an intake per kilogram of body weight. It then compares that intake to an example oral reference dose (RfD) to generate a hazard quotient (HQ).
The hazard quotient is a simple ratio that helps you see whether your estimated exposure is well below, near, or above a benchmark level used in many environmental health assessments. It is not a diagnosis or a regulatory determination, but it can help you understand your situation and prepare better questions for health or environmental professionals.
Underlying equation and variables
The calculator uses a standard intake equation from environmental risk assessment. It assumes that exposure comes from drinking water and food on a typical day and that your body weight is constant.
The total daily intake from water and food is summed and then normalized by body weight:
- Cw: concentration in drinking water (mg/L, milligrams per liter)
- V: volume of water consumed per day (L/day)
- Cf: residue concentration in food (mg/kg, milligrams per kilogram of food)
- F: mass of food eaten per day (kg/day)
- BW: body weight (kg)
- D: estimated daily intake (mg/kg-day)
To put this intake into context, the calculator divides D by an example oral reference dose (RfD):
In this tool, the RfD is set to 0.003 mg/kg-day as a generic illustrative value similar to some chronic oral RfDs used for certain pesticides. Actual regulatory values vary by chemical and by agency.
Interpreting the hazard quotient (HQ)
The hazard quotient compares your estimated exposure to a benchmark dose. It does not estimate the actual probability of getting sick, but it can indicate whether your exposure is low or high relative to a reference level.
| Hazard quotient (HQ) | Qualitative category | Typical next steps |
|---|---|---|
| < 1 | Below reference dose | Exposure is estimated to be below the illustrative RfD. Maintain good hygiene practices (washing produce, following local water guidance) and keep records of how you chose your input values. |
| 1 to 3 | Near or modestly above reference dose | Consider reducing intake where practical, for example by using filtered water, varying your diet, or choosing products with lower residue levels. If you are pregnant, have a chronic illness, or are assessing a child, discuss your concerns with a qualified health professional. |
| > 3 | Well above reference dose (screening concern) | Treat the result as a signal to act. Seek ways to quickly reduce exposure (alternative water sources, different food sources) and contact your local public health authority, physician, or a toxicologist for personalized advice and proper testing. |
These bands are meant for screening and prioritization, not as hard thresholds for safety or harm. People differ in their sensitivity, and RfDs already include uncertainty factors to protect more vulnerable groups.
Worked example
To see how the calculation works, consider the following scenario:
- Water concentration, Cw: 0.001 mg/L
- Water intake, V: 2 L/day
- Food residue, Cf: 0.02 mg/kg
- Food consumed, F: 0.5 kg/day
- Body weight, BW: 70 kg
First, calculate the total pesticide amount taken in each day:
- From water: 0.001 mg/L × 2 L/day = 0.002 mg/day
- From food: 0.02 mg/kg × 0.5 kg/day = 0.01 mg/day
Total daily intake (mass basis): 0.002 + 0.01 = 0.012 mg/day.
Now normalize by body weight:
D = 0.012 mg/day ÷ 70 kg ≈ 0.000171 mg/kg-day
Next, compute the hazard quotient using the illustrative RfD of 0.003 mg/kg-day:
HQ = 0.000171 ÷ 0.003 ≈ 0.057
This HQ is well below 1, so in this example the estimated exposure would be below the benchmark reference dose used in the calculator.
Comparison of key quantities
| Quantity | What it represents | Typical unit |
|---|---|---|
| Concentration in water (Cw) | Amount of pesticide per liter of drinking water | mg/L (milligrams per liter) |
| Concentration in food (Cf) | Residue level per kilogram of food | mg/kg (milligrams per kilogram) |
| Daily intake (D) | Total mass of pesticide per kilogram of body weight per day | mg/kg-day |
| Reference dose (RfD) | Benchmark daily exposure considered unlikely to cause appreciable risk over a lifetime, including safety factors | mg/kg-day |
| Hazard quotient (HQ) | Ratio of estimated intake to the RfD (screening indicator) | unitless |
Assumptions and limitations
This calculator is designed as an educational, screening-level tool. When you use or interpret the results, keep these key assumptions and limitations in mind:
- Single chemical only: The equation assumes all exposure comes from one pesticide. Real-world diets can involve mixtures of chemicals that may act differently.
- Oral route only: Only ingestion from drinking water and food is considered. Inhalation and dermal (skin) exposure are not included.
- Constant daily intake: The model assumes that your water intake, food intake, and residue levels are similar from day to day. Short-term peaks or seasonal variations are not modeled.
- Body weight is fixed: BW is treated as a constant; changes over time, growth in children, or weight loss/gain are not captured.
- Generic reference dose: The RfD used here (0.003 mg/kg-day) is an example value. Actual RfDs are chemical-specific, based on toxicological data, and can change as new evidence becomes available.
- Does not account for individual vulnerability: Children, pregnant people, older adults, and individuals with certain medical conditions may be more sensitive than the average person assumed in standard risk assessments.
Because of these limitations, an elevated HQ should be considered a signal to seek further information, not a definitive statement about health effects or legal compliance.
Safety information and disclaimer
The results from this calculator are for information and education only. They are not medical advice, toxicological advice, or a regulatory decision. Do not start, stop, or change any treatment, and do not ignore professional guidance, based solely on this tool.
If your estimated HQ is elevated or if you have symptoms or concerns related to chemical exposure, consult a qualified professional such as your physician, a clinical toxicologist, or your local or national public health authority.
Further reading and data sources
For more detailed and chemical-specific information on pesticide risks and reference doses, you may wish to consult reputable organizations such as:
- World Health Organization (WHO) guidelines on drinking-water quality and pesticide residues
- United States Environmental Protection Agency (EPA) Integrated Risk Information System (IRIS) and pesticide fact sheets
- European Food Safety Authority (EFSA) assessments of pesticide active substances
- National or regional food safety agencies and public health authorities
These sources can provide up-to-date RfDs, acceptable daily intakes, and monitoring data that are tailored to specific chemicals and local regulations.