Many pesticides achieve their intended use of killing pests by disrupting the nervous system. Due to similarities in brain biochemistry among many different organisms, there is much speculation that these chemicals can have a negative impact on humans as well. Children are especially vulnerable to exposure to pesticides, especially at critical windows of development.  Infants and children consume higher amounts of food relative to their body-weight, and have a more permeable blood–brain barrier, all of which can contribute to increased risks from exposure to pesticide residues. However in 2008 the OECD report that the existing guideline represents the best available science for assessing the potential for developmental neurotoxicity in human health risk assessment.