Limitations in Toxicity Studies:
Toxicology is a scientific discipline that studies the adverse effects of chemical substances on living organisms. Toxicology overlaps with biology, chemistry, pharmacology, and medicine, with roots that date back to Mathieu Orfila in 1813. Toxicologists work with companies and government agencies, attempting to identify potential dangers to public (human) health posed by chemical additives in food and cosmetics, safety testing of new drugs, and workplace safety concerns. The latter was a key area of study for Dr. Bradford Hill
Because tens of thousands of chemical formulations are used in workplaces, most are accompanied by Material Safety Data Sheets (MSDS). These are required documents in the workplace, assuming that workers actually read and fully understand them. You can see a typical example here. This particular one is an insecticide in the neonicotinoid family approved for use in most countries by regulatory agencies. Unfortunately the birds and bees are not equipped to read and understand such documents. Neither are people who are downwind, downsteam, or disadvantaged in their employment.
Many toxicity studies are carried out on animals, particularly if there is planned inference by extention to human toxicity. But in addition, toxicity studies can be directed toward non-target organisms. For example, a cry-protein toxin used to target mosquitos could be applied in lab studies to see if it impacts a species of frog. Such studies generally report results in terms of LD or lethal dose. So if a toxin is applied at a given concentration to a group of frogs, the LD50 would be the concentration at which 50% of the frogs in the study die. So referring back to the MSDS linked above, on page 5 is the following information:
LD50 Oral 175 mg/kg (rat)
LD50 Dermal > 5,000 mg/kg (rabbit)
LD50 Inhalation > 2.32mg/L 4 hr (rat)
The lethal dose (LD) methodology is lab-based and not long term. No confounding varaibles are present, as they would be in the real world. So no interaction effects. No effects on offspring. No bioaccumulation or biomagnification effects.
If bioaccumulation and biomagnification effect are ingnored in safety research, safety is far from guaranteed. This is a factor in a large body of research carried out by or accepted by regulatory agencies.
This is a very serious problem when we depend on lab toxicity studies for decision making.