The website calculates a value called the Acute Heath Effects Index for each ingredient of the products you use.† The Acute Health Effects Index depends on three things:
∑ the types and amounts of cleansers and pesticides that are used during an application,
∑ the types and amounts of toxic chemicals in the pesticides and cleansers that are used, and
∑ the degree of toxicity of the toxic chemicals contained in the pesticides and cleansers.
In contrast to chronic toxicity, acute toxicity is a response to a single dose of a chemical.† That is why the amount of product used per application is used when calculating the Acute Health Effects Index.
Acute toxicity varies widely from one chemical to the next, so the specific ingredients that are in the pesticides and cleansers that are used are important for the Acute Health Effects Index.† The concentration of each chemical is important as well.†
There is no single consistently evaluated and accepted measure of acute toxicity for chemicals. †The values chosen for calculating the Acute Health Effects Index are the oral LD50 and the 4-hr LC50.†
The oral LD50 is one measure of a chemicalís acute toxicity.† This is the amount of chemical which, when eaten, causes 50% of a population to die.† LD50s are usually given in units of milligram of chemical per kilogram of body weight.
A measure for a compoundís acute inhalation toxicity is its 4-hr LC50.† This is the concentration in air which causes 50% of a population to die after four hours of exposure.† LC50s are usually given in units of milligram of chemical per cubic meter of air.
Other measures of acute toxicity include dermal LD50s, LD100s, and several others, but the oral LD50 and the 4-hr LC50 are the most widely available values and were chosen for this reason.† The tier of sources for obtaining these values is
2) the National Toxicology Program (NTP) database, and
3) other (see references in data table).
Acute toxicity values are frequently available for a variety of animal species.† For calculating the Acute Health Effects Index, the oral LD50 and 4-hr LC50 for the most sensitive species of rodent are used. These values are converted to grams of chemical that would correspond to a 70 kg individual who breathes 20 cubic meters of air per day.
For example, if the oral LD50 for a chemical is 490 mg/kg, while the 4-hr LC50 is 100 mg/m3, then the corresponding oral dose for a 70 kg individual is
The corresponding inhalation dose for an individual who breathes 20 m3/d of air (the typical amount for a 70 kg individual) is
The Overall Acute Dose for a chemical is the least of the Acute Oral Ingestion Dose and the Acute Inhalation Dose.† The smaller of these two values is chosen so that the Acute Health Effects Index reflects the most sensitive exposure pathway.† For this example
Often, only one of these values (inhalation or oral) is available.
The Acute Health Effects Index for each chemical is the mass of the product used during an application, multiplied by the concentration of the chemical in the product, divided by the Overall Acute Dose for that chemical, divided by 1000, or
If the Acute Health Effects Index is greater than one, a window will pop up while the survey is being completed.† This window reminds visitors to the website to follow labeled instructions for product application carefully.