From a judgment of the district court denying claimant-appellant’s claims for herself as the widow and on behalf of the dependent child of an employee covered by Wyoming’s Occupational Disease Law, § 27-288, et seq., as amended, (repealed, § 4, Ch. 149, S.L.Wyo. 1975), arising out of the death of her husband, allegedly by malignancy caused by radiation, she appeals. We will affirm.
Section 27-290, of the Occupational Disease Law, stated in pertinent part:
“(a) The list of authorized compensable occupational diseases shall include:
* # # * * #
“(xxii) ionizing radiation, radiation poisoning or malignancy caused thereby. # * *))
Section 27-293 provided:
“When an employee has suffered a com-pensable occupational disease covered by this act, the employer’s account in whose employment said employee was last injuriously exposed to the hazards of the disease at the time of exposure shall alone be liable therefore, without right to contribution from any prior employer.”
Section 27-297(a) covered burden of proof:
“The burden in contested cases shall be upon the employee to make proper proof of his claim by a preponderance of the evidence, and to likewise prove by competent medical authority that this claim arose out of and in the course of his employment by showing by a preponderance of such evidence that:
“(i) there is a direct causal connection between the condition under which the work is performed and the occupational disease,
“(ii) the disease can be seen to have followed as a natural incident of the work as a result of the exposure occasioned by the nature of the employment,
“(iii) the disease can be fairly traced to the employment as the proximate cause,
“(iv) the disease does not come from a hazard to which workmen would have been equally exposed outside of the employment,
“(v) and the disease is incidental to the character of the business and not independent of the relation of employer and employee.”
The claimant’s husband had been employed as an underground uranium miner, as follows:
Jan. 8,1968-Feb. 27,1970 Continental Uranium Co.
Mar. 4,1970-Sept. 10,1970 Federal American Partners
Oct. 11,1970-Jan. 16,1971 Continental Uranium Co.
Jan. 18,1971-Dec. 29,1971 Federal American Partners
The appellee-employer was Olson’s last employer. While in that employment, he became ill and on May 23, 1973, died of lung cancer. The claimant at the trial asserted that her husband died of a lung cancer induced by occupational radiation exposure arising out of his last employment. The last employer denied liability, claiming that *712Olson had not been subjected to injurious radiation exposure during his employment by it, so there was no causal connection between the employment with it and the lung cancer and, additionally, that there was no certainty that his cancer developed in his employment as a uranium miner. It was admitted that the deceased was an habitual cigarette smoker, having smoked daily at least a package to a package and a half from 1949 until 1971. The record evidence indicates he may have smoked even more.
The court’s findings were:
“1. That it is unable to find that the Claimant has established by competent medical authority by a preponderance of the evidence that the disease of the decedent, Ralph R. Olson, did not come from a hazard to which the workman would have been equally exposed outside of his employment.
“2. That it is unable to find on the evidence in this case that the Claimant has established by the prescribed burden of proof that the disease in this case is not independent of the relation of Employer and employee.
“3. That it is unable to find that the Claimant has established that the disease is not independent of the relation of this particular Employer and this particular employee involved in these proceedings. “4. That it is unable to find from the evidence that this Employer is the one in which the last injurious exposure occurred, neither is it able to make a contrary finding, and so that portion of the resolution of this case against the Claimant is made on the failure of the Claimant to carry the burden of proof prescribed by statute.”
We see the only issue to be whether the trial judge erred in holding that the claimant failed in her statutory burden of proof.
Since the case is fact-oriented for disposition, the case has been predominantly studied and decided, having in mind the appellate rule that we will examine the evidence in the light most favorable to the prevailing party. P & M Cattle Company v. Holler, Wyo.1977, 559 P.2d 1019. Strangely enough here, the evidence most persuasive in support of the trial court’s position came from the claimant’s own expert witness. The employer’s expert witness, a medical doctor, with a considerable experience in the study and treatment of cancer in uranium miners, was not in substantial disagreement. The record discloses that the trial judge was tempted to allow the employer’s motion to dismiss at the close of claimant’s presentation in chief, but wisely determined to hear the evidence of the employer, in order that there be a complete record of all evidence on both sides and avoid a remand because of the risk involved in an improvident early dismissal and piecemeal trial. Furthermore, as noted by the district court, the statute invoked considerations upon which this court has not previously ruled in its technical aspects, peculiar to uranium mining.
There is some similarity between Workmen’s Compensation cases1 and this one under the since repealed Occupational Disease Law but the former type case does not have the specially applicable statutory sections we must here take into account. This court has considered, however, a similar case of failure of proof under the Occupational Disease Law but involving a different lung ailment. Hammond v. Hitching Post Inn, Wyo.1974, 523 P.2d 482. The claimant must conform to the burden imposed.
Dr. Victor E. Archer, a nationally recognized expert in the field of cancer induced by radiation, associated with the mining of uranium, testified for the claimant. He was commendably frank in his appraisal of the dead miner’s disease and its connotations.
*713It was Dr. Archer s testimony that there is a high incidence of lung cancer amongst uranium miners. In order to determine the amount of radiation to which decedent had been exposed in his lifetime, his body was disinterred and parts, particularly bones, removed for testing. The results of inhaling air laden with an inert gas, radon, a decay product of radiation, ends up as a further radiation decay product in the bones of a human being as lead-210. The amount of that end product in the bones can be measured and with adjustments for periods of nonexposure or noninjurious exposure will reveal with accuracy the amount of radon gas taken into the lungs during a lifetime of uranium mining.
As previously indicated, Olson had been employed by Continental Uranium Company upon his entry into his occupation as a miner in 1958 and worked for that company continuously until 1970, a period of about 12 years. He was with his last employer here intermittently for a total period of about 18 months. Clinical appearance of the cancer developed after 13 years of uranium mining. There is what is known as an induction-latent period, a length of time between when a man first starts uranium mining, and the advent of cancer. This period is usually around 15 years though the cancer may appear at any time after five years, here 13 years.
According to Dr. Archer, tobacco use to the extent engaged in by Olson can either be the cause of the cancer here involved or it may promote the development of cancer induced by radiation. The latter is referred to as a synergizing effect. Tobacco use also leaves lead-210 in the body. Dr. Archer explained that the incidence of lung cancer amongst uranium miners is greater to a definite extent among smoking miners than nonsmoking miners.
While the trial judge may have been able, at the most, to find that the cancer of which decedent died might have been induced by radiation from uranium mining in the first employer, the proof completely breaks down as far as “injurious exposure” with the last employer, with whom we are concerned, is involved. There was no proof that the working level of radiation in the Federal American Partners mine was not within practical prescribed limits of safety.2 The evidence in that regard fails also to show that Olson was even working in areas of the mine where radiation at any level was present. There was no proof that Olson was “injuriously exposed” to the hazards of radiation-induced cancer with the employer here.
The clincher, however, was when the following question and answer by Dr. Archer went into the record:
“Q. Can you tell from your records with medical certainty that the death of Mr. Olson occurred or was caused solely by radiation exposure?
“A. No. I don’t think we could be that certain about it.”3
Dr. Archer specifically testified that if the working level exposure of Olson was within the United States Government permissible limits, there would not be injurious exposure; it would not contribute to or promote a cancer induced several years earlier with a different company but not discovered until later. The proof of the employer was that the exposure was within the safe lim*714its. The claimant furnished no acceptable proof to the contrary.
If there is any reasonable basis for the findings of the trial judge as the fact finder, we must affirm. The outline we have just undertaken demonstrates the correctness of the district court and we likewise, as did the district court, hold there to have been a failure of proof under the applicable statutes, §§ 27-293 and 27-297, then in effect. For a similar case, see Garner v. Hecla Mining Company, 1967, 19 Utah 2d 367, 431 P.2d 794. For a case where there was a proven injurious exposure for a short period, see Climax Uranium Company v. Smith's Claimant, 1974, 33 Colo.App. 337, 522 P.2d 134.
We have considered that in the usual Workmen’s Compensation case, the law should be liberally construed in favor of an award. However, such a policy does not give us carte blanche authority to ignore clear statutory provisions and under the guise of construction extend the beneficent purpose of the law to a disease or injury that does not fall reasonably within the reach of legislative language. Pease v. Pacific Power & Light Company, Wyo.1969, 453 P.2d 887, 888; In re Hardison, Wyo. 1967, 429 P.2d 320, 322. As said in the latter case, the rule of liberality is not to be related to the evidence offered. 429 P.2d at 322. It is the burden of the employee to show the actual time of disability and cause under the statute then in effect. Bemis v. Texaco, Inc., Wyo.1965, 400 P.2d 529, reh. den., 401 P.2d 708. In this burden, the claimant has failed.
We need not consider the pertinence of the statute of limitations, § 27-308, an issue raised by the employer, making the Occupational Disease Law inapplicable when the last injurious exposure occurred before its effective date.
Affirmed.
. See Plummer v. Gladstone Hotel, 1958, 78 Wyo. 427, 328 P.2d 1118, where the appeal of a denied Workmen’s Compensation claim was based on an asserted erroneous determination of facts. Our duty in such cases is simply to search the record to ascertain the presence or absence of substantial evidence to support the district court.
. The standard of measurement is “Working Level Months” (abbreviated “WLM”), a term incorporating a particular fixed quantity of radiation exposure over a work period of one month. The federal government standard of maximum exposure at the time in issue was four “Working Level Months” per year. The only acceptable proof of exposure with the employer party here was a total of around three WLM (.76 in 1970 and 2.31 in 1971) over a period of 18 months, not regarded an injurious exposure. The government-established standard, if followed during a working life as a uranium miner, would not induce cancer by radiation.
. There must be a direct causal connection between the causal conditions under which the work is performed and the occupational disease. Section 27-297(a)(i). While statistically the risk of a uranium miner is increased, that does not rise to the standard of reasonable medical certainty to establish causal connection. O’Connor v. Industrial Commission, 1973, 19 Ariz.App. 43, 504 P.2d 966.