Gulf War syndrome, an umbrella term for a batch of neurological disorders experienced by nearly a quarter of the 700,000 veterans of the 1991 war, is attributable to “neurotoxic exposures,” a scientific panel told Congress on Monday. The report specifically points to a pesticide and anti-nerve-gas drug commonly used by the soldiers. The federal government has maintained for nearly two decades that syndrome symptoms are a result of post-traumatic stress.