This opinion was filed for record 

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... :(\Q[ 

\.'MY" . SUSAN L. CARLSON 

-~ SUPREMiCOURTCLERK 

IN TI-IE SUPREME COURT OF THE STATE OF WASHINGTON 

ROGER A. STREET, 

Respondent, NO. 93984-5 

v. 

ENBANC 

WEYERHAEUSER COMP ANY, 

Petitioner. Filed AUG 1 0 2017 ----'-----=..:::__:_:_-

STEPHENS, J.-Weyerhaeuser Company, Roger A. Street's former employer, 

challenges Street's award of industrial insurance benefits for his low back condition, a 

claimed occupational disease. An "occupational disease" is a disease that "arises 

naturally and proximately out of employment." RCW 51.08.140. In Dennis v. 

Department of Labor & Industries, 109 Wn.2d 467, 477, 745 P.2d 1295 (1987), this 

court held that a worker seeking benefits for an occupational disease must present expert 

medical testimony that the disease "arise[ s] 'proximately"' out of employment. 

Weyerhaeuser argues that in light of Dennis, such a worker must also present expert 

medical testimony that the disease "arises naturally" out of employment. 
Street v. Weyerhaeuser Company, 93984-5 

The Court of Appeals rejected Weyerhaeuser's argument, holding that neither 

Dennis nor any other appellate decision requires Street to present expert medical 

testimony to show that his back condition "arose naturally" from employment. Because 

there was medical testimony supporting the "arises proximately" requirement and lay 

testimony supporting the "arises naturally" requirement, the appeals court held that 

Street proved his low back condition is an occupational disease and affirmed the jury 

award of benefits. We affirm the Court of Appeals. 

BACKGROUND FACTS AND PROCEDURAL HISTORY 

Street worked for Weyerhaeuser or its subsidiary (Norpac) his entire career. In 

1991, Street began working in one of Norpac's paper mills, where he held various 

positions for the next 20 years. Although Street had back problems prior to working in 

the paper mill, he did not find the problems disabling until he was injured at the mill in 

2011. More than one year later, Street applied for workers' compensation benefits due 

to that injury. The Department of Labor and Industries (Department) treated the 

application as an injury claim and denied it as untimely. 

Later that year, the Department affirmed the denial and sent Street a separate 

letter stating that the claim was for an injury, not an occupational disease. Compare 

RCW 51.28.050 (worker must file injury claim within one year of the date on which 

the injury occurred), with RCW 51.28.055(1) (worker must file occupational disease 

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Street v. Weyerhaeuser Company, 93984-5 

claim within two years of the date the worker had notice of the occupational disease or 

of the ability to file a claim for disability benefits). Street appealed the Department's 

order and letter to the Board of Industrial Insurance Appeals (Board), clarifying that he 

intended to file an occupational disease claim. Weyerhaeuser moved for an order 

granting summary judgment and dismissing Street's appeal. An industrial appeals 

judge granted Weyerhaeuser partial summary judgment, dismissing Street's claim as 

untimely to the extent he alleged an injury, but directing the case to go forward on an 

occupational disease theory. 

The industrial appeals judge conducted hearings, at which Street, his family 

members, his supervisor, and three medical experts testified. 

Street testified that his duties as an assistant winder operator included placing 

cores-dense cardboard at the center of a paper roll-into the winder of the paper 

machine so that the machine could produce individual paper rolls. His duties also 

included monitoring paper machines, repairing broken machines, "manhandling" paper 

rolls by grabbing and pushing the core of the roll, bending over to sand cores, and 

tacking bar codes onto the finished paper rolls. The paper rolls were approximately 40 

to 50 inches in diameter and weighed on average 1,000 pounds. The cores, on which 

the rolls were placed, weighed on average 2 to 10 pounds. Street worked 12-hour shifts 

with few breaks, if any. Some of Street's work became automated over the last 10 

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Street v. Weyerhaeuser Company, 93984-5 

years, and during the last couple of years, Street worked in a less demanding monitoring 

role about 30 percent of the time. 

Richard T. Moore, Street's supervisor of two to five years, gave slightly different 

testimony regarding Street's role. Moore testified that Street held the less demanding 

monitoring role about 75 percent of the time, that Street sat approximately 20 percent 

of the time as an assistant winder operator, and that workers typically had help 

manhandling the paper rolls, which might happen O to 12 times a day. 

Dr. Patricia Peterson, Street's primary care physician of 20 years, testified that 

she was familiar with the nature of Street's work "[t]o some degree" and described his 

role in the paper mill as a "very heavy job, ... a moving job, ... [not] just a sit around 

and watch things go job." Clerk's Papers (CP) at 313,315,319,321. She testified that 

she diagnosed Street with chronic low back pain related to degenerative arthritis and 

degenerative disease of the spine, which can occur over time from repetitive use. 

Although on Street's short-term disability claim form she had checked a box indicating 

that the condition was not work related, she later testified on a more probable than not 

basis that the kind of work Street did, as opposed to everyday wear and tear of daily 

living, at least in part caused Street's low back condition because he used "a lot of his 

body weight" and his "abdominal muscles" in manhandling paper rolls. Id at 322-23, 

326. Dr. Peterson acknowledged that even though Street had come in with complaints 

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Street v. Weyerhaeuser Company, 93984-5 

of low back pain unrelated to work ( e.g., moving furniture, doing yard work), the 

repetition of handling paper rolls was a factor contributing to Street's low back 

condition. 

Dr. Yuri Tsirulnikov, an osteopathic physician who treated Street five to six 

times, testified that Street's work more probably than not contributed to his low back 

condition, though he could not say to "what extent" it contributed. Id. at 362,364, 367-

68, 371. He indicated that Street's weight, genetics, and "probably some other physical 

activities that he did at home" also contributed to Street's low back condition. Id. at 

384. 

Dr. Thomas Rosenbaum, a neurosurgeon who examined Street at 

Weyerhaeuser's request, opined that Street's work did not proximately cause his low 

back condition. He diagnosed Street with lumbar spondylosis and degenerative disc 

disease, and testified that genetics and age are the main factors contributing to these 

conditions. In his opinion, Street's physical exertion at work contributed to his low 

back condition "maybe ... two or three percent," if at all. Id. at 431-32. 

At the conclusion of the proceedings, the industrial appeals judge issued a 

proposed order and decision reversing the Department's denial of benefits. 

Weyerhaeuser petitioned the full Board for review. The full Board affirmed the 

Department's denial of benefits, but directed the Department to find that Street filed an 

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Street v. Weyerhaeuser Company, 93984-5 

occupational disease claim that was rejected because he failed to prove his low back 

condition arose "naturally and proximately" out of distinctive conditions of his 

employment. Id. at 49, 54-55. 

Street appealed the Board's order to Cowlitz County Superior Court. 

Weyerhaeuser moved for judgment as a matter of law on the ground that Street failed 

to present expert medical testimony that his low back condition "arose naturally" out of 

distinctive conditions of his employment. The superior court denied the motion and 

sent the case to trial. The jury found that Street's back condition is an occupational 

disease that arose "naturally and proximately" out of the distinctive conditions of his 

employment. Id. at 532. Based on the verdict, the superior court reversed the Board's 

order and remanded to the Department with directions to accept Street's occupational 

disease claim. Id. at 534-35. 

Weyerhaeuser appealed to Division Two of the Court of Appeals, which 

transferred the matter to Division One of the Court of Appeals. Order Transferring 

Cases, Street v. Weyerhaeuser Co., No. 48559-1-II (Wash. Ct. App. Aug. 16, 2016). In 

an unpublished decision, the Court of Appeals affirmed, holding that Street was not 

required to present medical testimony to satisfy the "arises naturally" requirement, and 

that the evidence was sufficient to support a finding that Street's back condition 

qualifies as an occupational disease. Street v. Weyerhaeuser Co., No. 75644-3-1, slip 

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Street v. Weyerhaeuser Company, 93984-5 

op. at 1, 4, 7 (Wash. Ct. App. Nov. 28, 2016) (unpublished), http://www.courts. 

wa.gov/opinions/pdf/756443.pdf. 

Weyerhaeuser then filed a petition for review in this court, which we granted. 

Street v. Weyerhaeuser Co., 187 Wn.2d 1025, 391 P.3d 457 (2017). 

ANALYSIS 

The Industrial Insurance Act (IIA), Title 51 RCW, provides "sure and certain 

relief for workers, injured in their work." RCW 51.04.010. Workers "who suffer[] 

disability from an occupational disease in the course of employment" are entitled to 

"the same compensation benefits" as injured workers. RCW 51.32.180. In the present 

case, Street alleges that his chronic low back condition is an occupational disease. CP 

at 57. 

"'Occupational disease' means such disease ... as anses naturally and 

proximately out of employment." RCW 51.08.140. In Dennis, 109 Wn.2d 467, this 

court discussed the requirements for such a claim. "Arises proximately" means that 

employment conditions "'must be the proximate cause of the disease ... so that the 

disease would not have been contracted but for the [ employment] condition.'" Id. at 

4 77 (footnote omitted) ( quoting Simpson Logging Co. v. Dep 't of Labor & Indus., 32 

Wn.2d 472,479,202 P.2d 448 (1949)). This "causal connection ... must be established 

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Street v. Weyerhaeuser Company, 93984-5 

by competent medical testimony which shows that the disease is probably, as opposed 

to possibly, caused by the employment." Id. 

"Arises naturally" requires a worker to 

establish that his or her occupational disease came about as a matter of course 

as a natural consequence or incident of distinctive conditions of his or her 

patiicular employment. The conditions need not be peculiar to, nor unique to, 

the worker's particular employment. Moreover, the focus is upon conditions 

giving rise to the occupational disease ... and not upon whether the disease 

itself is common to that particular employment. The worker, in attempting to 

satisfy the "naturally" requirement, must show that his or her particular work 

conditions more probably caused his or her disease ... than conditions in 

everyday life or all employments in general; the disease ... must be a natural 

incident of conditions of that worker's particular employment. Finally, the 

conditions causing the disease ... must be conditions of employment, that is, 

conditions of the worker's particular occupation as opposed to conditions 

coincidentally occurring in his or her workplace. 

Id. at 481. Although the court in Dennis discussed what a worker must prove to 

demonstrate a disease "arises naturally" out of employment conditions, it did not 

specifically address whether expert medical testimony is required to prove it. That issue 

is now before us. 

I. The "Arises Naturally" Requirement Need Not Be Established by 

Expert Medical Testimony 

As noted, to satisfy the "arises naturally" requirement, a worker must prove 

that his or her occupational disease came about as a natural consequence of 

distinctive employment conditions. Id. Weyerhaeuser contends that whether a 

disease "arises naturally" from distinctive conditions of employment constitutes an 

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Street v. Weyerhaeuser Company, 93984-5 

issue of medical causation that must be proved through expert medical testimony. 

Pet. for Review at 8, 19. Street counters that while the "arises naturally" requirement 

presents an issue of general causation, it does not present an issue of medical 

causation requiring expert testimony. Suppl. Br. of Resp't at 2. Rather, it is a 

causation issue pure and simple; as with most factual causation determinations, it 

does not require expert opinion. Id. at 5; Br. ofResp't at 12-13. 

We believe the remedial nature of the IIA, the standard governing the need 

for expert testimony, and our case law all support Street's argument. We discuss 

each of these reasons more fully below. 

a. The IIA Is Broadly Construed in Favor of Workers 

This court has consistently held that because the IIA "is remedial in nature," 

it must be "liberally construed in order to achieve its purpose of providing 

compensation to all covered employees injured in their employment, with doubts 

resolved in favor of the worker." Dennis, 109 Wn.2d at 470. "With this principle 

in mind," id., both the legislature and this court have expanded occupational disease 

coverage under the IIA. The trend toward liberal coverage supports Street's 

argument that a worker need not present expert medical testimony to prove an 

occupational disease "arises naturally" from employment. 

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Street v. Weyerhaeuser Company, 93984-5 

Dennis is the leading case on occupational disease. There, this court held that 

the "historical development of occupational disease coverage in Washington" 

supports the conclusion that a preexisting condition exacerbated by work comes 

within the definition of an "occupational disease." Id. at 472. This court explained 

that at the time the IIA was enacted, there was "no coverage for disability resulting 

from occupational disease[,] only injuries sustained performing certain 

extrahazardous work." Id. The legislature subsequently "passed the first law 

providing compensation for disability resulting from certain enumerated diseases," 

including "specific conditions resulting from repetitive work activities." Id. at 473. 

Eventually, the legislature "again broadened coverage by eliminating the list of 

enumerated compensable diseases, and enacting the present definition of 

occupational disease," although compensation was available only for extrahazardous 

employment. Id. Finally, the legislature eliminated the extrahazardous employment 

requirement and "provided coverage for disability resulting from occupational 

disease in all employment." Id. This court summarized, "From 'no coverage' to the 

present broad definition of occupational disease, the Legislature has repeatedly and 

consistently provided expanded coverage for disability resulting from occupational 

disease." Id. at473-74. This court concluded that it was a natural next step to expand 

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Street v. Weyerhaeuser Company, 93984-5 

coverage to disabilities resulting from "work-related aggravation of ... preexisting 

nonwork-related diseases." Id. at 474. 

In addition to expanding coverage, this court has at least in two instances 

relaxed the worker's burden of proof for an occupational disease claim. First, in 

Sacred Heart Medical Center v. Carrado, 92 Wn.2d 631, 632-33, 600 P.2d 1015 

(1979), this court held that the medical testimony was sufficient to support the jury's 

finding that a nurse had contracted hepatitis as a result of her employment even 

though the medical testimony indicated that it is nearly impossible to pinpoint the 

source of the disease. In so holding, this court stated that while "the causal 

connection between a [worker's] physical condition and his employment must be 

established by" medical testimony, our cases do not require a medical opinion on 

"the ultimate issue" in every instance. Id. at 636. Rather, "[i]t is sufficient if the 

medical testimony shows the causal connection." Id. In other words, it is sufficient 

if "a reasonable person can infer" from the medical testimony, in conjunction with 

lay testimony, "that the causal connection exists." Id. at 637. This suggests there 

are no "magic words" for proving the issue of medical causation. Indeed, in later 

describing its holding, this court stated, "Sacred Heart does not require each [worker 

claiming] occupational disease coverage to prove an increased risk of disease-based 

disability due to conditions of his or her particular employment, but instead eases 

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Street v. Weyerhaeuser Company, 93984-5 

the burden of proof requirement." Dennis, 109 Wn.2d at 482 (second emphasis 

added). 

Second, m interpreting the "arises naturally" requirement, this court 

specifically rejected a lower court's more stringent definition. Id. at 478-79 

(rejecting Dep't of Labor & Indus. v. Kinville, 35 Wn. App. 80, 664 P.2d 1311 

(1983)). "Dennis relaxed the requirements of' Kinville, "which required the worker 

to prove 'that the conditions producing his disease are peculiar to, or inherent in, his 

particular occupation."' Kaiser Alum. & Chem. Corp. v. McDowell, 58 Wn. App. 

283, 286-87, 792 P.2d 1269 (1990) (quoting Kinville, 35 Wn. App. at 87). In Dennis, 

this court held that "[t]he conditions need not be peculiar to, nor unique to, the 

worker's particular employment." 109 Wn.2d at 481. Instead, they need only be 

"distinctive" conditions "of the worker's particular occupation as opposed to 

conditions coincidentally occurring" in the workplace. Id. 

Both the legislature's amendments to and this court's decisions interpreting 

the occupational disease statute evidence a trend toward expanded coverage and a 

more relaxed burden of proof. Allowing a worker to prove the "arises naturally" 

requirement without the necessity of medical testimony aligns with this trend. 

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Street v. Weyerhaeuser Company, 93984-5 

b. Expert Medical Testimony Is Necessary Only for Issues of Medical 

Causation, and the "Arises Naturally" Requirement Is Not Such an 

Issue 

In determining whether the "arises naturally" requirement must be proved 

through expert medical testimony, it is helpful to consider in what circumstances 

expert testimony is generally useful. "The admissibility of expert testimony in 

Washington is governed by" Evidence Rule (ER) 702. Reese v. Stroh, 128 Wn.2d 

300, 305, 907 P.2d 282 (1995). That rule provides that "[i]f scientific, technical, or 

other specialized knowledge will assist the trier of fact to understand the evidence 

or to determine a fact in issue," a qualified expert "may testify thereto in the form of 

an opinion." ER 702. With regard to expert medical testimony, the "general rule" 

is that 

expert medical testimony is required on only those matters "strictly 

involving medical science". The basic question is whether the particular fact 

sought to be proved is such as is "observable by [a layperson's] senses and 

describable without medical training". 

Smith v. Shannon, 100 Wn.2d 26, 33, 666 P.2d 351 (1983) (matters involving 

medical science include "the nature of the harm which may result and the probability 

of its occurrence" because "[ o ]nly a physician ... is capable of judging what risks 

exist and their likelihood of occurrence" ( alteration in original) ( citation omitted) 

( quoting 2 JOHN HENRY WIGMORE, EVIDENCE IN TRIALS AT COMMON LAW§ 568, at 

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779 (rev. 1979); Bennett v. Dep 't of Labor & Indus., 95 Wn.2d 531, 533, 627 P.2d 

104 (1981))). 

In the context of occupational disease claims, matters involving medical 

science include the "'cause and extent"' of the disability. Eyer v. Dep't of Labor & 

Indus., l Wn.2d 553, 555, 96 P.2d 1115 (1939) (quotingAtl. Ref Co. v. Allen, 1939 

OK 116, 185 Okla. 194, 195, 90 P .2d 659); see also Hoff v. Dep 't of Labor & Indus., 

198 Wash. 257,266, 88 P.2d 419 (1939) ("[U]pon a medical question regarding the 

nature and effect of a particular ailment ... those who are versed in the science of 

medicine are better able than are we to form a true and accurate opinion."). 

Weyerhaeuser contends that the "arises naturally" requirement is an issue of 

medical causation requiring expert medical testimony that "the work activities at 

Weyerhaeuser were distinctive, compared to activities that are common to 

employment generally and daily life, when viewed as a cause of lumbar 

spondylosis." Br. of Appellant at 19. We find this argument unavailing. "Arises 

proximately" means that the employment conditions must be the proximate cause of 

the disease. Dennis, l 09 Wn.2d at 477. "Arises naturally" means that the conditions 

of a worker's particular employment are distinctive, i.e., different from, 

employments in general or activities of daily living. Id. at 481. The first requirement 

involves an issue of medical causation, but the second requirement pertains to 

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Street v. Weyerhaeuser Company, 93984-5 

observable job activities. See, e.g., City of Bremerton v. Shreeve, 55 Wn. App. 334, 

340 n.5, 777 P.2d 568 (1989) ("The 'naturally' requirement ... addresses the work 

connection ... , while the 'proximately' requirement is addressed by the 'but for' 

test."). 

Viewing the requirements this way explains why the court in Dennis explicitly 

stated only that expert medical testimony is necessary for the "arises proximately" 

requirement. See 109 Wn.2d at 4 77. Medical professionals specialize in diagnosing 

patients' conditions, not in familiarizing themselves with various job duties. Street 

aptly notes that many treating physicians would balk at any requirement that they 

"become experts as to job duties that exist in all employments in general, or testify 

as to what constitutes activities of daily living, versus distinctive job duties." Suppl. 

Br. of Resp't at 5. Amicus Washington State Association for Justice Foundation 

further observes, "[A] medical professional has no particular qualifications that 

would help the trier of fact to determine whether the conditions of a worker's 

particular employment are distinctive." Br. of Amicus Curiae Wash. State Ass'n for 

Justice Found. at 13; see also Wash. Supreme Court oral argument, Street v. 

Weyerhaeuser Co., No. 93984-5 (June 13, 2017), at 5 min., 07 sec. through 6 min., 

00 sec., video recording by TVW, Washington State's Public Affairs Network, 

http://www.tvw.org (Weyerhaeuser's counsel noting that medical professionals 

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Street v. Weyerhaeuser Company, 93984-5 

become familiar with employment conditions in part through patients' explanations 

of their job duties). Instead, "[a] witness familiar with the worker's job requirements 

and the particular manner in which the worker performed those job requirements can 

provide evidence to assist the trier of fact to determine whether job conditions are 

distinctive." Br. of Amicus Curiae Wash. State Ass'n for Justice Found. at 13-14; 

see also Bennett, 95 Wn.2d at 533 ("[L]ay witnesses may testify to such aspects of 

physical disability of an injured person as are observable by their senses and 

describable without medical training."). 

Given that the "arises naturally" requirement presents the nonscientific 

question of whether the conditions of a worker's particular employment are 

distinctive, it stands to reason that it can be established by lay testimony without the 

need for expert medical opinion. 

c. Washington Case Law Does Not Suggest the "Arises Naturally" 

Requirement Must Be Proved Through Expert Medical Testimony 

No Washington case holds that expert medical testimony is necessary to 

satisfy the "arises naturally" requirement. Weyerhaeuser argues, however, that 

language in several cases suggests a worker must prove a "distinctive employment 

cause" through expert medical testimony. Br. of Appellant at 15-18 ( emphasis 

added). 

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Street v. Weyerhaeuser Company, 93984-5 

As an initial matter, Weyerhaeuser is mistaken to the extent it argues a worker 

must show a "distinctive risk" or "distinctive cause" to meet the "arises naturally" 

requirement. See, e.g., Pet. for Review at 5 ("Neither doctor addressed whether 

claimant's work activities presented a distinct risk of causing lumbar spondylosis." 

(emphasis added)); Br. of Appellant at 19 ("The issue whether particular work 

conditions constituted a 'distinctive' cause of a medical condition presents a medical 

question." (emphasis added)). As Street and supporting amicus point out, this "is no 

different than the argument that a worker must show that the particular employment 

exposed him or her to a greater risk of contracting the occupational disease than 

would other employments or everyday life." Br. of Amicus Curiae Wash. State 

Ass'n for Justice Found. at 15; see also Suppl. Br. of Resp't at 11-12. Because we 

previously rejected this "greater risk" requirement in Dennis, l 09 Wn.2d at 482, 

Weyerhaeuser is mistaken to the extent it advocates for adoption of this 

requirement. 1 A worker need only show "distinctive conditions" of employment to 

meet the "arises naturally" requirement. 

1 As Street's counsel articulated at oral argument, requiring a worker to prove a 

distinctive cause or a distinctive risk of employment is inconsistent with the legislative 

history of the IIA, which now allows occupational disease claims for all employment, not 

just extrahazardous employment. Wash. Supreme Court oral argument, supra, at 19 min., 

16 sec. through 20 min., 41 sec.; see also Dennis, 109 Wn.2d at 473-74. 

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Weyerhaeuser's argument is also unpersuasive because the cases on which it 

relies do not support its position. In Dennis, a sheet metal worker filed an 

occupational disease claim for osteoarthritis localized in his wrists. 109 Wn.2d at 

468-69. This court reaffirmed that the "arises proximately" requirement "must be 

established by competent medical testimony which shows that the disease is 

probably, as opposed to possibly, caused by the employment." Id. at 477. Because 

the worker's attending physician testified that "more probably than not, the 

osteoarthritis . . . was made symptomatic and disabling by . . . repetitive tin 

snipping," this court held that there was "sufficient medical evidence in the record 

from which a trier of fact could infer" the "arises proximately" requirement. Id. 

Although the court discussed the "arises naturally" requirement, it neither stated that 

the requirement must be established by expert medical testimony nor focused on 

whether that requirement was satisfied. Instead, the court concluded merely that 

there was sufficient evidence to support the inference that the disabling wrist 

condition "arose naturally and proximately" out of employment. Id. at 483. Dennis 

therefore does not support Weyerhaeuser' s argument. Had the court intended to 

require expert medical testimony for the "arises naturally" requirement, it could have 

stated so explicitly. 

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Street v. Weyerhaeuser Company, 93984-5 

In Potter v. Department of Labor & Industries, 172 Wn. App. 301, 304, 306-

07, 289 P.3d 727 (2012), a lawyer filed an occupational disease claim after noticing 

strong odors in her newly remodeled office, experiencing bloody noses and fatigue, 

and being diagnosed with multiple chemical sensitivity disorder. The court found 

the lawyer failed to satisfy the "arises proximately" requirement because the medical 

testimony established only a possibility, not a probability, that she was exposed to 

chemicals in the remodeled office that made her sick. Id. at 311. The court similarly 

found that the lawyer failed to satisfy the "arises naturally" requirement because, as 

the Board had found below, "'[r]emodels are everywhere, and by no means limited 

to law offices, or to work for that matter."' Id. at 316. The court therefore upheld 

the denial of benefits. Id. at 304. Nowhere in Potter did the court state it was 

upholding the denial of benefits because the lawyer failed to present medical 

testimony that remodels were a distinctive condition of her employment. To the 

contrary, the decision suggests that medical testimony is not necessary to make such 

a showing, as the Board made that determination on its own. 

In Gastv. Department of Labor & Industries, 70 Wn. App. 239,241,852 P.2d 

319 (1993 ), a maintenance worker filed an occupational disease claim for a stressrelated disease allegedly caused by being the subject of workplace rumors. On 

appeal, she challenged the trial court's jury instruction, which read: 

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"If you find that Vickie Gast suffered a disease which was 

proximately caused by occurrences in her workplace, then you must consider 

whether or not such occurrences are distinctive conditions of her particular 

employment. This court has already ruled, as a matter oflaw, as follows: 

"(1) Rumors ... by one's co-workers, are not, by themselves, 

distinctive conditions of employment." 

Id. at 242. The appeals court affirmed the denial of benefits and held that the trial 

court "correctly determined as a matter of law that rumors . . . are not distinctive 

conditions of employment." Id. at 243. "Such conditions are unfortunate 

occurrences in everyday life or all employments in general. Their occurrence at a 

specific workplace is coincidental." Id. As in Potter, 172 Wn. App. at 316, where 

the Board determined on its own that the lawyer's conditions of employment were 

not distinctive, the lower court in Gast found on its own that the maintenance 

worker's conditions of employment were not distinctive, 70 Wn. App. at 243. This 

suggests that expert medical testimony is not necessary to satisfy the "arises 

naturally" requirement. 

As in Gast, id. at 243-44, where the court held that rumors were not distinctive 

conditions of employment, the crux of the reasoning in Witherspoon v. Department 

of Labor & Industries, 72 Wn. App. 847, 851, 866 P.2d 78 (1994), was that a 

coughing incident was merely coincidental with employment and could have 

happened anywhere. In Witherspoon, id. at 848-49, a slaughterhouse worker filed 

an occupational disease claim for meningitis he allegedly contracted from a 

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Street v. Weyerhaeuser Company, 93984-5 

coworker who had coughed in his face in the locker room. In reversing the jury's 

award of benefits, the appeals court stated the "meningitis did not come about" 

naturally because "the medical testimony was that meningitis is spread" through the 

mouth and nose, and occurs almost everywhere. Id. at 851. The worker's exposure 

to meningitis in the workplace "was merely coincidental and not a result of any 

distinctive conditions of his employment." Id. Although the court relied on medical 

testimony to find the worker did not satisfy the "arises naturally" requirement, 

nowhere in the decision did the court say that such testimony is necessary. We do 

not read the decision as requiring expert medical testimony. 

Similarly, in Wheeler v. Catholic Archdiocese of Seattle, 65 Wn. App. 552, 

567, 829 P.2d 196 (1992), rev 'din part on other grounds, 124 Wn.2d 634, 642-43, 

880 P.2d 29 (1994), the court focused on the coincidental nature of the employment 

conditions. There, a worker filed a negligent supervision claim against her 

employer, which argued the claim should have been dismissed under the IIA's 

exclusive remedy provision. Id. at 565. On appeal, the court found the trial court 

did not err in refusing to dismiss the negligent supervision claim because it did not 

fall within the basic coverage of the IIA. Id. at 566, 568. The worker's claim was 

for a mental disability allegedly resulting from her supervisor's harassment. Id. at 

566. Without mentioning any medical testimony, the court found that "[t]he 

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conditions ... were not particular to her occupation, but only coincidentally occurred 

in her workplace." Id. at 567-68. Wheeler thus does not suggest that the "arises 

naturally" requirement must be established by medical testimony. 

As these cases illustrate, Washington case law does not support 

Weyerhaeuser's argument that a worker must prove the "arises naturally" 

requirement through expert medical testimony. See also Ruse v. Dep 't of Labor & 

Indus., 138 Wn.2d 1, 7-8, 977 P.2d 570 (1999) (affirming the denial of benefits 

without reaching the "arises naturally" requirement because the medical testimony 

did not support the "arises proximately" requirement); Shreeve, 55 Wn. App. at 335-

36 (upholding the award of benefits in part because the worker "presented the 

testimony of three doctors to support her contention that her kidney disease arose 

'proximately' out of her employment," but not stating whether such testimony 

supported the requirement that the disease arose "naturally" out of employment 

(emphasis added)); McClelland v. ITT Rayonier, Inc., 65 Wn. App. 386, 387, 393, 

828 P.2d 1138 (1992) (rejecting the worker's occupational disease claim because he 

conceded that "his job was not unusually stressful" and the evidence therefore 

showed his depression was "caused simply by his own subjective but unrealistic 

view of the situation at" work rather than distinctive conditions of his employment). 

Rather, the remedial purpose of the IIA, the standard governing the admissibility of 

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Street v. Weyerhaeuser Company, 93984-5 

expert testimony, and the cases all indicate expert medical testimony is not required 

to prove a condition arises naturally out of employment. 

IL The Evidence Was Sufficient To Support the Jury's Finding That 

Street's Chronic Low Back Condition "Arose Naturally and 

Proximately" Out of Distinctive Conditions of His Employment 

The remaining issue is whether sufficient evidence supported the jury's 

verdict that Street's low back condition is an occupational disease. At the superior 

court, the "party attacking the [Board's] decision" has the burden of proving it is not 

"prima facie correct." Ruse, 138 Wn.2d at 5; RCW 51.52.115. At the appellate 

court, however, "'review is limited to examination of the record to see whether 

substantial evidence supports the findings made after the superior court's de novo 

review, and whether the [superior] court's conclusions of law flow from the 

findings."' Ruse, 138 Wn.2d at 5 (quoting Young v. Dep't of Labor & Indus., 81 

Wn. App. 123, 128, 913 P.2d 402 (1996)). Substantial evidence exists if it 

"convince[s] an unprejudiced, thinking mind of the truth of that to which the 

evidence is directed." Ehman v. Dep 't of Labor & Indus., 33 Wn.2d 584, 597, 206 

P .2d 787 (1949). The appellate court views the evidence "in the light most 

favorable" to the party who prevailed at the superior court. Bennett, 95 Wn.2d at 

534. 

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Street v. Weyerhaeuser Company, 93984-5 

As noted, to succeed on an occupational disease claim, a worker must prove 

that the disease "arose naturally and proximately" out of employment. See Dennis, 

109 Wn.2d at 481-82. The "arises proximately" requirement "must be established 

by competent medical testimony which shows that the disease is probably, as 

opposed to possibly, caused by the employment." Id. at 4 77. "If, from the facts and 

circumstances and the medical testimony given, a reasonable person can infer that 

the causal connection exists, the evidence is sufficient." Bennett, 95 Wn.2d at 533. 

In reviewing the medical testimony on this issue, the "long-standing rule of law in 

workers' compensation cases [is] that special consideration should be given to the 

opinion of a [worker's] attending physician." Hamilton v. Dep 't of Labor & Indus., 

111 Wn.2d 569, 571, 761 P.2d 618 (1988). As established above, the "arises 

naturally" requirement need not be established by medical testimony. Rather, lay 

testimony may establish that the "occupational disease came about as a matter of 

course as a natural consequence or incident of distinctive conditions of'' 

employment. Dennis, 109 Wn.2d at 481. 

Weyerhaeuser contends that Street's occupational disease claim fails because 

he "presented no expert testimony that addressed, directly or indirectly, the question 

whether his work activities were distinctive, compared to other employments and 

the activities of daily living." Br. of Appellant at 21. Weyerhaeuser emphasizes that 

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Street v. Weyerhaeuser Company, 93984-5 

neither Dr. Peterson nor Dr. Tsirulnikov compared Street's work activities to 

activities of daily living, and Dr. Rosenbaum testified that Street's work conditions 

were not distinctive. Id. Street counters that Dr. Peterson's testimony was sufficient 

to prove that his low back condition "arose naturally and proximately" out of 

distinctive conditions of his employment because Dr. Peterson accurately described 

Street's work duties and opined that Street's employment more probably than not 

caused his low back condition. Suppl. Br. ofResp't at 7-9. 

While the evidentiary question presents a close call, we uphold the jury's 

verdict. Viewing the evidence in the light most favorable to Street and giving special 

consideration to Dr. Peterson's testimony, we hold there was sufficient evidence to 

support the jury's finding that Street's low back condition is an occupational disease. 

Dr. Peterson's testimony and Dr. Tsirulnikov's testimony were sufficient to 

establish that Street's low back condition "arose proximately" out of his 

employment. Dr. Peterson testified that Street's work more probably than not caused 

his low back condition, as opposed to everyday wear and tear. CP at 322-23, 326. 

Similarly, Dr. Tsirulnikov testified that Street's work more probably than not 

contributed to his low back condition, but he could not say to what extent. Id. at 

367-68, 371. Although Dr. Rosenbaum testified that Street's work did not 

proximately cause his low back condition, id. at 411, the evidence must be viewed 

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Street v. Weyerhaeuser Company, 93984-5 

in the light most favorable to Street and need only reasonably suggest a causal 

connection. See Bennett, 95 Wn.2d at 533-34. Nor was the jury obligated to credit 

Dr. Rosenbaum's opinion. From the evidence, a rational trier of fact could infer the 

required causal connection between Street's employment and his low back 

condition. 

Street's testimony and his supervisor's testimony were sufficient to establish 

that Street's low back condition "arose naturally" out of distinctive conditions of his 

employment. Both Street and his supervisor testified that Street's duties included 

manhandling paper rolls that weighed on average 1,000 pounds. CP at 236-37, 261, 

288, 300-01. Street further testified that the paper machines he worked on are the 

world's biggest and fastest paper machines. Id. at 230. "The weight of ... testimony 

is for the jury." Bennett, 95 Wn.2d at 534. A jury could conclude that manhandling 

paper rolls on the world's biggest and fastest machines was a distinctive condition 

of employment, as it does not occur in everyday life nor in all employments. 

Although we hold expert medical testimony is not required to establish Street's 

distinctive conditions of employment, Dr. Peterson's testimony is also helpful in 

resolving this issue. Dr. Peterson testified that Street used "a lot of his body weight" 

and his "abdominal muscles" in his employment, and she compared Street's job to 

her sedentary job. CP at 322-23. She testified that "people who use the body parts 

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Street v. Weyerhaeuser Company, 93984-5 

that are required in their job tend to wear those parts out." Id. at 323. From this 

testimony, a jury could conclude that Street's job required more physical rigor than 

everyday life and work in general. 

Considering all the testimony, we hold that substantial evidence supported the 

jury's finding that Street's low back condition is an occupational disease. 

III. Street Is Entitled to Attorney Fees on Appeal 

Street requests attorney fees on appeal. Both the superior court and the Court 

of Appeals awarded Street attorney fees pursuant to RCW 51.52.130. CP at 535; 

Street, slip op. at 13. That provision states, 

If, on appeal to the superior or appellate court from the decision and order of 

the board, said decision and order is reversed or modified and additional 

relief is granted to a worker ... or in cases where a party other than the 

worker ... is the appealing party and the worker's . . . right to relief is 

sustained, a reasonable fee for the services of the worker's ... attorney shall 

be fixed by the court. 

RCW 51.52.130(1). 

Because we affirm the lower courts' determination that Street's low back 

condition is an occupational disease, Street's right to relief is sustained on 

Weyerhaeuser's appeal and he is entitled to attorney fees. 

CONCLUSION 

We affirm the Court of Appeals. The remedial nature of the IIA, the standard 

governing the use of expert testimony, and our precedent all support the conclusion 

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Street v. Weyerhaeuser Company, 93984-5 

that a worker seeking industrial insurance benefits need not present expert medical 

testimony to satisfy the "arises naturally" requirement of an occupational disease 

claim. A worker need only present expert medical testimony to satisfy the "arises 

proximately" requirement. Given that Street's attending physician testified that his 

low back condition was more probably than not caused by his work, and given that 

Street and his supervisor testified as to Street's duties working in the paper mill, 

substantial evidence supported the jury's finding that Street's low back condition 

constitutes an occupational disease. 

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Street v. Weyerhaeuser Company, 93984-5 

WE CONCUR: 

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