* Dose Makes the Poison: The saying "the dose makes the poison" is true. Even water, essential for life, can be toxic in high doses.

* Individual Sensitivity: People react differently to substances based on factors like age, health, genetics, and even body size. What might be harmless for one person could be toxic to another.

* Context is Key: The environment, route of exposure (ingestion, inhalation, skin contact), and other factors influence a substance's toxicity.

* Long-Term Effects: Some substances may have delayed or long-term effects, making it challenging to determine their true toxicity.

However, we can talk about "relatively non-toxic" substances:

* Substances with Low Toxicity: Some substances have a very high threshold for toxicity. For example, water, salt, and sugar are relatively non-toxic in normal amounts.

* Substances with Specific Uses: Some substances, like cleaning products, are designed to be toxic to certain organisms (like bacteria or mold) but relatively safe for humans in proper use.

* Substances with Unknown Toxicity: There are many substances we haven't fully studied or understand their potential long-term effects.

It's crucial to remember:

* Safety Precautions: Always follow instructions and safety guidelines for handling any substance, even those considered "non-toxic."

* Environmental Impact: Even substances considered safe for humans can have negative impacts on the environment.

* Continuous Research: Scientists are constantly learning more about the toxicity of substances, and our understanding of what's safe may change over time.

In essence, it's more accurate to think about substances on a spectrum of toxicity rather than in absolute terms.