The employer and insurer appeal from the compensation judge’s determination that the employee developed occupational asthma.  We affirm.

The issue before the compensation judge was whether Troy Parker, the employee, developed occupational asthma as a result of his employment with Teamvantage Molding, Inc., the employer.  Mr. Parker testified that he had been diagnosed with asthma when he was a small child and received extensive treatment for this condition throughout his childhood, including a hospitalization when he was eleven or twelve.  The employee also testified that his asthma improved during his teen years and, after graduation from high school in 1989, he was able to join the Marines and serve four years with no problems.

After his discharge from the Marines, Mr. Parker returned to Minnesota and worked for a few months in 1993 as a security guard at Grand Casino Hinckley.  He then obtained a temporary job at Teamvantage working 12-hour shifts on the weekend.  The employer produces molded plastic parts, typically to be used in the assembly of products by other companies.  The employee’s temporary job was to monitor a machine that inserted springs into plastic parts and to clear any jams that occurred during the process.

Mr. Parker was hired to work on a full-time, permanent basis at Teamvantage in January 1994, and he worked there until August 2008.  In his employment at Teamvantage, Mr. Parker worked a number of positions:  press operator, material handler, and setup technician.  In his various assignments, the employee mixed plastic pellets and dye in cardboard barrels, loaded the mixed pellets into the hoppers of molding machines, operated machines that melted the pellets and produced molded plastic parts, cleaned or purged molding machines of plastic residue using various chemicals, and set up molds to be used in the machines.  All of this work was performed in one large room, and Mr. Parker testified he was exposed to chemical fumes, dust, and smoke when he was working.  At the hearing, the employer introduced into evidence Material Safety Data Sheets (MSDS) of 31 chemicals used in the plant.  Some chemicals were identified as being relatively benign, but a number were identified in the MSDS as producing fumes and dust which could result in respiratory irritation and symptoms including shortness of breath and chest tightness.

Mr. Parker testified that his treatment for asthma after he left the service began in 1993.  The records from Mr. Parker’s family physician regarding his treatment for asthma begin in 1996 with a notation of acute asthma and bronchitis.  From 1996 until the beginning of 2007, the employee was seen a number of times for asthma, and he was prescribed medication and the use of an inhaler.  A pulmonary function test in February 2007 was read as showing moderate obstructive lung disease.

In June 2008, Mr. Parker was referred to Dr. Christine Wendt, a pulmonary specialist.  After his first appointment, Dr. Wendt commented in her chart notes, “I am concerned about his occupational exposure.” Testing done in July 2008 showed severe obstructive lung disease.  Mr. Parker testified that in the last eight months he worked at Teamvantage, he was using his inhaler five or six times each shift he worked.  Dr. Wendt noted that in a phone call on August 11, 2008, the employee had reported increasing shortness of breath, and she restated her concern that “his fixed obstruction may be due to work-related exposures.”  Mr. Parker left Teamvantage on disability leave as of August 15, 2008.  Dr. Wendt stated in her chart notes from September 26, 2008, that after Mr. Parker stopped working he had improvement in his pulmonary function testing and in tightness in his chest.  Mr. Parker continued to treat for his asthma with medication and the use of an inhaler after he went on disability.  In chart notes from Mr. Parker’s appointment on February 23, 2009, Dr. Wendt’s assessment was “chronic obstruction pulmonary disease, likely from advanced asthma and occupational exposure.”  Pulmonary function tests done in 2009 characterized his obstructive lung disease as “moderate.”  In the history from an appointment on June 22, 2009, Dr. Wendt stated, “he had significant occupational exposure such as inhaling solvents and fumes from melting plastics.  This is consistent with occupational asthma.”

The employee filed a claim petition in June 2010, alleging he was entitled to workers’ compensation benefits from occupational exposure he developed during his employment at Teamvantage.  In its answer, the employer and insurer denied Mr. Parker’s condition was work-related.

Mr. Parker was seen by Dr. Thomas Mulrooney for an independent medical examination on behalf of the employer and insurer on November 8, 2010.  Dr. Mulrooney had pulmonary function tests done and concluded that “these findings indicate mild obstructive airflow limitation.”  He also reviewed Mr. Parker’s medical records and the Material Safety Data Sheets.  Dr. Mulrooney concluded that “Mr. Parker’s work at Teamvantage through August 2008 did not cause, aggravate, or accelerate his chronic lung disease and asthma condition.”  Dr. Mulrooney based his opinion, in part, on his conclusion that the acute exacerbations for which the employee saw physicians were not identified as being the result of an exposure at work, but rather the result of allergic reactions in his personal life.

At the request of his attorney, Mr. Parker saw Dr. David Bonham at St. Paul Lung Clinic on February 14, 2011.  Dr. Bonham reviewed the medical records, Dr. Mulrooney’s report, and Mr. Parker’s deposition.  He also interviewed Mr. Parker about his employment and reported that “from 1993 to 2008, he worked for Regal Plastics, also known as Teamvantage Molding.  In his occupation, he was exposed to plastic resins and a variety of other chemical fumes, both from the machine melting plastic materials, and from the solvents and other cleaning solutions used to service the machines involved.  He reports that he did not wear a respirator.  He did not think that the ventilation was adequate in the work environment.”  Dr. Bonham diagnosed Mr. Parker as having “occupational asthma that is characterized by demonstrating moderately severe, mostly fixed flow obstruction with exacerbations associated with exposure to a variety of respiratory irritants and other conditions.”  As to causation, Dr. Bonham stated, “Mr. Parker’s occupational asthma was caused and substantially contributed to by his exposures to various toxic materials in his work environment.”

Teamvantage sent Mr. Parker to a second IME, this one with Dr. David Johnson, on October 12, 2011.  Dr. Johnson reviewed the Material Safety Data Sheets, Dr. Mulrooney’s report, and Dr. Bonham’s report.  Dr. Johnson also discussed Mr. Parker’s employment at Teamvantage with him, and conducted pulmonary function testing.  Dr. Johnson concluded that the employee had “chronic bronchial asthma.  This has been a life long problem.  This is primarily allergic in nature.”  Dr. Johnson also stated that, in his opinion, Mr. Parker’s asthma was “not substantially or appreciably caused, aggravated or accelerated by any exposure at Teamvantage Molding.”  Dr. Johnson disagreed with the diagnosis of occupational asthma, stating that “occupational asthma reflects new asthma arising out of a workplace exposure without any prior history of asthma.”  Dr. Johnson also rated the employee’s permanent partial disability based on the pulmonary function testing as being 53% of the whole body pursuant to Minn. R. 5223.0560, subp. 3.C.(1) and 5223.0560, subp. 3.B.

The employee’s claim was heard by Compensation Judge Rolf Hagen on January 18, 2012.  The parties stipulated to a number of issues, leaving in dispute the issues of causation, entitlement to temporary partial disability benefits, and the extent of permanent partial disability.  In his findings and order, issued March 8, 2012, the compensation judge adopted the opinions of Drs. Wendt and Bonham and concluded that the employee developed occupational asthma as a result of his exposure “to various toxic materials in his work environment.”  The compensation judge awarded benefits including permanent partial disability as rated by Dr. Johnson.  The employer and insurer have appealed the findings of causation.

On appeal, the employer and insurer argue that this case involves a “rather unusual circumstance” in which a preexisting “lifelong” condition, asthma, becomes a work-related condition imposing liability on the employer and insurer.  The employer and insurer claim that in such a situation, there must be “the highest scrutiny” of the foundation for a medical opinion establishing causation.  The employer and insurer argue that under a test of the highest scrutiny, foundation does not exist for the medical opinions relied on by the compensation judge in this case and his decision must be remanded or reversed.

Each workers’ compensation case is unique in the claims, the parties, and the evidence produced at hearing, but this case is not unique or even “rather unusual” in finding liability where a work injury or exposure aggravates a preexisting non-work condition so as to result in disability and liability under the workers’ compensation statute.

“It is well established that a preexisting disease or infirmity of the employee does not disqualify a claim arising out of the employment if the employment aggravated, accelerated, or combined with the disease or infirmity to produce disability for which compensation is sought.”  Gillette v. Harold, Inc., 257 Minn. 313, 317, 101 N.W.2d 200, 204, 21 W.C.D. 105, 109 (1960).  “While it is recognized that the employer is not the insurer of the health of his employees, he must take them as he finds them with all the infirmities they bring to their employment, and he assumes the risk of having a preexisting condition aggravated by some injury which might not be harmful to a normal, healthy person.”  Gillette, at 257 Minn 322, 101 N.W.2d 207, 21 W.C.D. 114.

This court has previously recognized the principles set forth in Gillette as being applicable in a claim alleging occupational asthma.  We have affirmed the compensation judge’s factual determination that occupational exposure aggravated preexisting asthma so as to result in a compensable disability.  Foster v. Metro Produce Distrib., 63 W.C.D. 218 (W.C.C.A. 2002) and Treazise v. United Hospital, 64 W.C.D. 160 (W.C.C.A. 2003).  We have also affirmed a compensation judge’s factual determination that work exposure did not result in occupational asthma.  Vinkemeier v. Crown Holdings, slip op. (W.C.C.A. Feb. 26, 2002).

This court must affirm the factual determination of a compensation judge if it is supported by substantial evidence.  Minn. Stat. § 176.421, subd. 1.  It is the function of the compensation judge to consider competing medical opinions, and a compensation judge’s decision in that regard will generally be affirmed so long as the accepted opinion has adequate foundation.  Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985); Smith v. Quebecor, 63 W.C.D. 566 (W.C.C.A. 2003).  Foundation for a medical opinion may be established by taking a history from the patient, performing an examination, and reviewing medical records.  Scott v. Southview Chevrolet, 267 N.W.2d 185, 188, 30 W.C.D. 426, 430 (Minn. 1978).

The employer and insurer challenge the foundation for the opinions of Drs. Wendt and Bonham and argue the lack of foundation is demonstrated by the evidence produced by the cross-examination of the employee, the reports of Drs. Johnson and Mulrooney, and the MSDS, all of which, it is argued, are contrary to the information assumed by the employee’s supporting medical opinions.

With regard to the cross examination of the employee, the employer and insurer point to the admissions by the employee that he had asthma most of his life and had been on medication ever since 1993.  He also stated that irritants such as smoke or grass clippings exacerbated his symptoms.  The employee’s extensive medical treatment for asthma and the effect of his encounters with irritants in his non-work life are set out in some detail in the medical records.  Both Drs. Wendt and Bonham had the records available to them at the time they rendered their opinions.  The question here was not whether the employee had asthma before his employment at Teamvantage, because it was obvious to all physicians that he did.  The issue rather is whether his exposure to chemicals during the course of his 14-year employment at Teamvantage was a substantial contributing factor in his present condition as well.

The employer and insurer state in their brief that Dr. Bonham had assumed that Mr. Parker’s asthma had resolved by late childhood when that was not the case.  We do not read Dr. Bonham’s report as stating that Mr. Parker’s asthma was in some manner completely gone, but we must note in this regard that Mr. Parker’s asthma had resolved sufficiently by the time he had graduated from high school that Mr. Parker was able to pass a physical exam that allowed him to join the Marines, complete basic training, and serve for four years with no evidence of problems with asthma.  We conclude, as did the compensation judge, that Dr. Bonham did not misstate the employee’s medical history.

The employer and insurer also argue that neither Dr. Wendt nor Dr. Bonham had the MSDS available to them for review, but the relevance of the MSDS to this case is unclear.  Neither Dr. Johnson nor Dr. Mulrooney seemed to find them of any significance.  Dr. Mulrooney referred to one of the 31 chemicals as being “the most irritant,” but he did not think it likely that inhalation of that chemical was likely in the workplace because of the odor of the chemical.  He did not mention any of the other chemicals identified in the MSDS as causing lung irritation or tightness in the chest.  Dr. Johnson apparently did not find the identity of the chemicals listed on the MSDS to be relevant since he reached his conclusion as to causation based on his stated belief that occupational asthma does not occur in the case of preexisting asthma.

Dr. Wendt and Dr. Bonham had adequate foundation for their opinions.  The information available to them establishing foundation included the numerous chemicals identified in the MSDS as irritants to the respiratory system producing the same symptoms that the employee complained of, the employee’s testimony as to the dust, fumes, smoke and inadequate ventilation he experienced on the job, the employee’s increased use of his inhaler at work, his course of treatment with Dr. Wendt over several months both before and after his departure from employment, and the improvement in his pulmonary function testing after he left Teamvantage.

In the present case, the purported lack of information goes to the weight to be given to the medical opinions.  Schulenberg v. Corn Plus, 65 W.C.D. 237 (W.C.C.A. 2005).  It is within the discretion of the compensation judge to assess the weight and sufficiency of a medical expert’s opinion.  Raine v. Lil Rascals Daycare, No. WC09-5024 (July 7, 2010).  It is apparent from the compensation judge’s memorandum that he carefully considered the arguments of the employer and insurer, the same arguments made by the employer and insurer before this court.  The compensation judge provided a detailed rationale for his determination, and we are unable to conclude that his determination is not supported by substantial evidence.

The decision of the compensation judge is affirmed.