In 2012 genetically engineered (GE) crops were grown by 17. scientific
In 2012 genetically engineered (GE) crops were grown by 17. scientific weight of evidence from these hundreds of studies have not revealed unique risks associated with GE feed some groups are calling for more animal feeding studies including long-term rodent studies and studies in target livestock species for the approval of GE crops. It is an opportune time to review the results of such studies as have been done to date to evaluate the value of the additional information obtained. Requiring long-term and target animal feeding studies would sharply increase regulatory compliance costs and prolong the regulatory process associated with the commercialization of GE crops. Such costs may impede the development of feed crops with AP24534 enhanced nutritional characteristics and durability particularly in the local varieties in small and poor developing countries. More generally it is time for regulatory evaluations to more explicitly consider both the reasonable and unique risks and benefits associated with the use of both GE plants and animals in agricultural systems and weigh them against those associated with existing systems and those of regulatory inaction. This would represent a shift away from a GE evaluation process that currently focuses only on risk assessment and identifying ever diminishing marginal hazards to a regulatory approach that more objectively evaluates and communicates the likely impact of approving a new GE herb or animal on agricultural production systems. and analyses. Further the need to evaluate both the risks and benefits in regulatory evaluations is discussed given the weight of scientific evidence on the safety and performance of GE crops that have been commercialized to date. Short-term rodent feeding studies The protocols for 90-d rodent studies were adapted from those for toxicological studies  and are intended to assess feed safety. This protocol recommends 10 animals per sex and per group with three doses of the test material and a control group. It was developed to test the toxicology of a chemically defined molecule (e.g. a drug) not complex materials like GE feed. It becomes somewhat AP24534 problematic to appropriately “dose” the GE feed because diets must be balanced to meet the nutritional requirements of the rodents. Too much of a single crop or species in the diet may result in deleterious nutritional effects and associated phenotypes independent of the GE status of the crop. GE feeding studies typically incorporate 33% GE animal feed in the AP24534 test diet. Ideally the GE line is compared to its near isogenic counterpart produced in the same location and environment and possibly also a non-GE line (conventional comparator) considered to be safe. The latter is included to estimate the natural variability of analytes seen within the crop species. Several studies have revealed that environmental factors (such as field location planting sampling time crop management practices) and genetic factors like line/breed and mutagenesis can result in more AP24534 variability in gene expression between samples than is observed resulting from GE [10-12]. The failure of many researchers to appropriately match their experimental GE diets to appropriate isogenic and nutritionally comparative control diets has resulted in some of the most controversial and highly criticized GE feed safety studies. Long-term and multigenerational animal feeding studies Ninety-day rodent toxicology feeding studies are AP24534 not designed to measure effects on reproduction or development. Likewise they are not designed NBN to detect long term effects in animals or the effect that eating a GE-based diet has on the next generation. This has resulted in a call for more long term and multigenerational animal feeding studies. Although it should be noted that analyses of available data indicate that for a wide range of substances reproductive and developmental effects are not potentially more sensitive endpoints than those examined in subchronic toxicity assessments . Several review papers that summarize the results of long-term and multigenerational feeding studies in a variety AP24534 of species have been published recently [2 14 The duration of published long-term feeding studies using a GE-based diet ranged from 110 d [17-19] to 728 d . The longest multigenerational study involved ten generations of quail fed up.