The hazards of synthetic (anthropogenic) chemicals

Currently, there is a highly politicized debate on the comparative risks of naturally occurring and synthetic chemicals. Since humans are often exposed to complex mixtures of both classes of chemicals, the real-world value of this debate is unclear. However, in any such comparison, it is important to realize that some naturally occurring substances - such as lead or tobacco - have been so altered or disturbed by human activity that they are best considered as products of human activity, or anthropogenic. Reasons for concern over synthetic and anthropogenic chemicals include: persistence and propensity for long-term storage in biota and the environment; structural similarity to endogenous biomolecules; and additivity to natural hazards.