Del. Code tit. 19 § 2342
Unless the employer during the continuance of the employment has actual knowledge that the employee has contracted a compensable occupational disease or unless the employee, or someone in the employee's behalf, or some of the employee's dependents, or someone on their behalf, gives the employer written notice or claim that the employee has contracted one of the compensable occupational diseases, which notice to be effective shall be given within a period of 6 months after the date on which the employee first acquired such knowledge that the disability was, could have been caused or had resulted from the employee's employment, no compensation shall be payable on account of the death or disability by occupational disease of such employee.
19 Del. C. § 2342