The Appeal CommissionThe Workers Compensation Act of Manitoba

Preamble

The worker is appealing the decision made by Review Office of the Workers Compensation Board ("WCB") which determined that his left ear hearing loss deterioration was not related to his exposure to chemicals in the workplace and therefore he was not entitled to early replacement of his left hearing aid. A hearing was held on March 7, 2013 to consider the matter.

Issue

Whether or not the worker is entitled to early replacement of his left hearing aid.

Decision

That the worker is not entitled to early replacement of his left hearing aid.

Decision: Unanimous

Background

In 2007, the WCB accepted the worker's claim for a left ear hearing impairment related to his exposure to siren noise in his work environment.

In a letter dated October 30, 2008, the worker was advised by his WCB case manager that the WCB would cover the costs associated with a hearing aid for his left ear. The case manager further advised the worker that he may be entitled to a replacement hearing aid in approximately five years time assuming his hearing aid had malfunctioned, or he had further deterioration in his hearing and his current hearing aid did not meet his hearing loss requirements.

On August 9, 2010, the worker advised the WCB that his hearing aid was now two years old and he was experiencing further hearing loss difficulties. The worker said he attended an audiologist who indicated that his exposure to the chemical Toluene could cause hearing loss difficulties. The worker noted that he was exposed to this particular chemical on a regular basis during his employment history. On November 24, 2010, the worker provided the WCB with the audiologist's report to support that his hearing had deteriorated in his left ear and that he needed a replacement hearing aid.

In a report to the WCB dated September 24, 2010, the audiologist stated:

[The worker] has been exposed to noise and chemicals through his work environment. There is a synergistic relationship between noise and chemicals, which can damage balance and hearing mechanism. Safe levels of either agent can synergistically result in significant balance and auditory injury. The chemicals that [the worker] would have been exposed to are called organic solvents, which include Carbon Disulphide, Trichloroethylene, Styrene, Xylene and Toluene. The configuration, degree and type of hearing loss, as well as the significant shift in hearing are all consistent with ototoxicity.

On December 4, 2010, the WCB's ENT consultant stated that the reports on file did not explain why the worker's hearing had deteriorated in his left ear. He noted that exposure to ototoxic fumes would not explain the unilateral hearing loss. The consultant suggested that a CT scan of the temporal bones be arranged to find out whether there was any abnormality in the inner ear.

A CT scan of the temporal bones was conducted on January 11, 2011. The report stated:

There is a congenitally aberrant vessel which extends from the left middle cranial fossa through some of the left labyrinthine air cells and exits the skull just superior to the left mandibular condyle. The aberrant vessel is lateral to the middle ear cleft and is likely completely incidental in nature. No definite significant abnormality is noted.

In a report dated February 23, 2011, an ENT specialist noted that the worker's hearing in his left ear had significantly deteriorated. He commented that there was a synergistic relationship between noise and chemicals that can cause hearing loss. The ENT specialist stated that he was unable to find any other causes to explain the significant deterioration in the worker's hearing loss and that the placement of the T-tube did not result in any significant subjective or objective improvement in the worker's hearing levels.

On April 7, 2011, an external radiologist reviewed and commented on the worker's CT scan dated January 11, 2011.

On July 10, 2011, the WCB's ENT consultant stated:

I have discussed the CT scan findings and the aberrant blood vessel with (the external radiologist). He indicated that this aberrant blood vessel is most probably a vein and its course is lateral or away from the hearing nerve and the hearing organ. He is of the opinion that this aberrant blood vessel would have no impact on the worker's hearing in the left ear.

The WCB requested and received a copy of the worker's medical chart from 1988 to the present.

On January 17, 2012, the employer provided the following information:

• Its employees are exposed to over 70 organic agents repeatedly in their job. The agents of combustion may be in the form of gas, vapors or particulate.
• The chemicals are products of combustion and were not chemicals employed by the employees themselves.
• The worker attended 42 sites in 2009 and 2010. It was not possible to determine exposure to specific chemicals over any period.
• Its employees would be exposed to a range of noises comparable to a light industry or earth-moving equipment working environment.
• Personal protective equipment was assigned to and were available to all of its employees.

On February 4, 2012, the WCB's ENT consultant stated that the early replacement of the worker's left hearing aid could not be justified on the basis of exposure to ototoxic chemicals. He noted that the worker's audiologist was unable to find any literature to support unilateral ototoxicity. He noted that ototoxic chemicals affect both the hearing organ and the balance organ in the inner ear. Ototoxicity caused severe dizziness as well as hearing loss in both ears. The ENT consultant said he reviewed the worker's hearing loss forms, the report from the treating physician and ENT specialist and noted that the worker did not mention any complaints regarding dizziness. He said that many toxic chemicals caused abnormalities in the nervous system and there was no indication on the file that the worker suffered from a neurological disorder.

On February 4, 2012, the worker was advised that he was not entitled to a replacement hearing aid based on his exposure to ototoxic chemicals or further noise exposure in the workplace. The case manager's decision was based on the following findings:

• the sirens were removed from the vehicle rooftops around 2004 and were placed in the front grill to reduce noise exposure.
• the worker was provided with a different job in 2010 with minimal noise exposure; and
• the opinion outlined by the WCB ENT consultant dated February 4, 2012.

On May 24, 2012, the Worker Advisor Office appealed the case manager's decision to Review Office. The worker advisor referred to evidence on file to support that the worker's left ear hearing loss deterioration was causally related to his 2007 compensable condition and that the WCB was responsible to replace his left hearing aid.

On June 29, 2012, Review Office determined that the worker was not entitled to a new left hearing aid as the evidence on file did not establish that the deterioration of hearing in his left ear was caused by exposure to ototoxic chemicals or further noise exposure at his workplace between 2008 and 2010. On July 23, 2012, the worker appealed Review Office's decision to the Appeal Commission and a hearing was arranged.

Following the hearing on March 7, 2013, the appeal panel met to discuss the case and requested an opinion from an independent ENT specialist with respect to the worker's left-sided hearing loss deterioration and its relationship to exposure to chemicals in the workplace. A report from the independent ENT specialist dated August 2, 2013 was later received and was forwarded to the worker for comment.

On September 17, 2013, the appeal panel met further to discuss the worker's appeal and decided to request additional information from the independent ENT specialist. In this regard, the appeal panel provided the ENT specialist with a copy of the worker's prior claims with the WCB (2008 and 2010) in which the worker claimed an allergic reaction to irritants in his work environment. The ENT specialist was asked whether this new information had any effect on the opinion he outlined in his August 2, 2013 report. A copy of the ENT's response to the appeal panel dated November 29, 2013 was received and was forwarded to the worker for comment.

On January 8, 2014, the appeal panel met further to discuss the case and consider the worker's final submission of December 18, 2013.

Reasons

Applicable Legislation

The Appeal Commission and its panels are bound by The Workers Compensation Act (the “Act”), regulations and policies of the Board of Directors.

Under subsection 4(1) of the Act, where a worker suffers personal injury by accident arising out of and in the course of employment, compensation shall be paid to the worker by the WCB.

Worker’s Position

The worker appeared on his own behalf at the hearing and was accompanied by his daughter. The worker's position was that his left ear deterioration between 2008 and 2010 was attributable to exposure to noise and ototoxic chemicals in the course of his work. It was submitted that the fact that his hearing loss was not bilateral was not determinative and that the possibility of unilateral damage remained. Medical literature was provided which referenced asymmetric hearing loss associated with ototoxic medication. It was also submitted that it was plausible that the worker's already compromised left ear experienced deterioration in hearing as a result of further noise and chemical exposure whereas the right ear was not vulnerable in the same way.

The worker acknowledged that while the quantification and identification of exposure to specific chemicals could not be determined, there was without question exposure to known toxins. The worker was regularly exposed to carbon monoxide, which was a known cause of ototoxicity. The worker reported that the carbon monoxide alarm he wore in the course of his duties routinely went off, indicating he was being exposed to unacceptable levels of the agent. The average time spent at a site would be 4 to 5 hours, and the duration of exposure to chemical products of combustion and other contaminants was significant. The worker advised that since leaving his position, he had not experienced any additional hearing loss. As soon as the toxic exposures were stopped, his hearing stabilized.

Overall, the worker's position was that his work exposure to toxins caused the hearing in his left ear to deteriorate between 2008 and 2010. As a result, he was seeking nothing more than the early replacement of his hearing aid in favour of one that would provide adequate coverage for his compromised hearing.

Analysis

The issue before the panel is whether or not the worker is entitled to early replacement of his left hearing aid. In order for the worker’s appeal to be successful, the panel must find that the additional hearing loss in the worker's left ear which necessitated early replacement of his left hearing aid was related to his work duties. On a balance of probabilities, we are not able to make that finding.

The key question to be answered is whether ototoxicity, or ear poisoning, from exposure to chemicals during the course of employment resulted in damage to the worker's left ear during the period 2008 to 2010.

The worker's audiologist provided a report dated September 24, 2010 which stated there is a synergistic relationship between noise and chemicals which can damage balance and hearing mechanisms. The audiologist opined that the worker's configuration, degree and type of hearing loss, as well as the significant shift in hearing were all consistent with ototoxicity.

On February 4, 2012, the WCB ENT consultant provided an opinion which concluded that the request for early replacement of the left hearing aid could not be justified on the basis of exposure to ototoxic chemicals. The opinion noted that ototoxicity affects both ears and not just one since the toxin reaches the inner ear through the blood stream. It was also noted that ototoxicity causes severe dizziness as well as hearing loss in both ears, but there was no mention of complaints regarding dizziness or a neurological disorder.

At the hearing, the worker referred to numerous medical articles which suggested that asymmetric hearing loss could be experienced as a result of the ingestion of certain medications. Medical literature was also provided regarding "potentiation" which was described as follows: "In some cases, a substance will not cause hearing loss by itself, but can exacerbate a hearing loss caused by noise. This process is called potentiation. Also, a substance that is ototoxic can interact synergistically with noise (i.e., the combined biological effect of two hazards is greater than either alone)."

Following the hearing, the panel felt that it did not have sufficient information regarding the likelihood of potentiation as contributing to the worker's left sided hearing deterioration. We therefore arranged for an independent ENT specialist to review the worker's files and conduct a review of the literature to provide an opinion regarding the relationship between the worker's medical condition and his workplace exposures.

In response to the panel's request, an independent third party specialist provided a four page report dated August 2, 2013. The summary opinion arrived at by the specialist was as follows:

The actual cause of this claimant's hearing loss is likely related to noise exposure. After review of the literature and assessment of the process known as potentiation, it should be noted that the individual has no other directly attributable health issues from these toxic exposures. There is a probability that exposure to chemicals in the workplace has potentiated or accelerated the ongoing loss in the left ear. However, due to the lack of available documentation of the individual's exposure, it makes it impossible to state which toxic chemicals were involved, in what amount, and over what period of time. While I suspect the probability of potentiation is present, I would have to put the probability of this concomitant occurrence no higher than a 50 percent probability (and likely less).

Following receipt of the independent specialist's opinion, the worker noted that in fact, he did file two other WCB claims for an allergic reaction to irritants in the work environment (one of which was accepted as a temporary aggravation of a pre-existing angioedema). The ENT specialist was asked to review the two other WCB claim files and comment on whether the information on the other two claims had any effect on his opinion. In a response dated November 29, 2013, he stated: "I do not think that this new information changes my opinion from my August 2, 2013 letter. Specifically, this does not change my opinion in regards to the effect of potentiation on the affected ear."

This claim involves a relatively unique situation which is not frequently encountered by the Appeal Commission. The worker presented a compelling argument which was supported by medical literature, and he is to be commended for his reasoned approach to the issue. To assist in its deliberations, the panel requested an independent expert to conduct a review of the situation. The ENT specialist's opinion was that the probability of potentiation was no higher than 50 percent and was probably less. As such, this fails to meet the balance of probabilities test. The panel felt that the specialist's opinion was well researched and considered, and we see no reason to vary from same. While the panel gave careful consideration to the points raised by the worker, unfortunately, there is insufficient support to find for his position. In the result, we find that the worker's left ear deterioration is not attributable to workplace exposures and he is therefore not entitled to early replacement of his left hearing aid.

The worker's appeal is dismissed.

Panel Members

L. Choy, Presiding Officer
A. Finkel, Commissioner
M. Kernaghan, Commissioner

Recording Secretary, B. Kosc

L. Choy - Presiding Officer

Signed at Winnipeg this 5th day of February, 2014