Jamaiya Oglesby v. Baltimore School Associates, et al., No. 26, September Term, 2022

LEAD-BASED PAINT – EXPERT OPINION TESTIMONY – SOURC E CAUSATION – IQ LOSS – SUMMARY JUDGMENT – Supreme Court of Maryland * held that trial court abused its discretion by excl uding testimony of plaintiff’s causation expert witness in lead-based paint case. In ruling on motion to preclude and making determinations as to whether expert’s opinion had s ufficient factual basis, trial court resolved genuine disputes of material fact, and, in doing so, abused its discretion. Expert’s opinion that plaintiff’s exposure to lead-based pai nt at property was significant contributing factor to plaintiff’s alleged injuries (other than IQ loss) was supported by sufficient factual basis and admissible, as expert had adequate supply of data from which to form opinion, and methodology expert used reliably supported opin ion reached. Supreme Court remanded case, however, for further p roceedings consistent with Court’s holding in Rochkind v. Stevenson, 471 Md. 1, 236 A. 3d 630 (2020), for determination as to whether methodology used by expert was sufficien tly reliable to permit expert to render specific opinion that plaintiff’s exposure to lead resulted in loss of IQ points, should plaintiff seek to present such evidence at trial. Having concluded that trial court abused its discre tion in granting motion to preclude, Supreme Court also held that trial court erred in g ranting summary judgment. Trial court’s ruling—that plaintiff was unable to prove negligenc e without expert’s testimony as to causation—was not warranted. Plaintiff presented s ufficient evidence that property was reasonable probable source of exposure to lead and that exposure was significant contributing factor to alleged injuries to establis h prima facie case of negligence, irrespective of admissibility of expert’s opinion a s to IQ loss.

* At the time of the grant of the petition for a writ of certiorari in this case, the Supreme Court of Maryland was named the Court of Appeals of Maryland. At the November 8, 2022 general election, the voters of Maryland ratif ied a constitutional amendment changing the name of the Court of Appeals of Maryland to the Supreme Court of Maryland. The name change took effect on December 14, 2022.IN THE SUPREME COURT

OF MARYLAND*

No. 26 September Term, 2022

______________________________________

JAMAIYA OGLESBY

v. BALTIMORE SCHOOL ASSOCIATES, ET

AL.

______________________________________

Fader, C.J. Watts Hotten Booth Biran Gould Eaves,

JJ.

______________________________________

Opinion by Watts, J.

______________________________________

Filed: July 26, 2023

*At the November 8, 2022 general election, the vote rs of Maryland ratified a constitutional amendment changing the name of the Court of Appeals of Maryland to the Supreme Court of Maryland. The name change took effect on Decemb er 14, 2022. Circuit Court for Baltimore City Case No. 24-C-18-000268 Argued: March 2, 2023This case arises out of a plaintiff’s attempt to us e expert testimony in a lead-based

paint case to establish a property as a source of e xposure to lead and a significant factor contributing to her alleged injuries including a lo ss of intelligence quotient (“IQ”) points. Jamaiya Oglesby, Petitioner, initiated a lawsuit in the Circuit Court for Baltimore City against Baltimore Schools Associates, 1 Crowninshield Management Corporation, Jolly Company, Inc., and the Estate of Mendel Friedman (t ogether, “Respondents”) for negligence, negligent misrepresentation, and a viol ation of the Maryland Consumer Protection Act. Ms. Oglesby alleged that Responden ts, who owned and managed an apartment building (the “property”) in which she li ved as a child, were liable for injuries she sustained as a result of exposure to lead-based paint at the property. Ms. Oglesby designated Sandra Hawkins-Heitt, Psy.D., as an expe rt in the areas of clinical psychology and neuropsychology. Dr. Hawkins-Heitt evaluated M s. Oglesby and concluded that she suffered from cognitive impairments or deficiencies in multiple areas and had an IQ of 80. Ms. Oglesby designated as a vocational expert Mark Lieberman, M.A., a Certified

Rehabilitation Counselor. Mr. Lieberman evaluated Ms. Oglesby and found that she had numerous limitations and qualified as a “Cognitivel y Disabled” person. Ms. Oglesby designated Steven Elliot Caplan, M.D., as an expert in the area of pediatric medicine to testify with respect to causa tion. Dr. Caplan reviewed 24 sets of records pertaining to Ms. Oglesby, including the re ports of Dr. Hawkins-Heitt and Mr.

1 Although the case captions in both appellate courts identify the party as “Baltimore School Associates,” the parties in their briefs use the name “Baltimore Schools Associates.”- 2 -

Lieberman, and authored a report setting forth his opinions. Dr. Caplan concluded that Ms. Oglesby’s likely exposure to lead at the property w as a significant contributing factor to bringing about the cognitive deficiencies and impai rments found by Dr. Hawkins-Heitt and Mr. Lieberman as described in his report, and to a loss of approximately 3 to 4 IQ points. In reaching his opinion as to Ms. Oglesby’s IQ loss , Dr. Caplan relied on two studies—the Canfield study 2 and the Lanphear study 3 —which conclude, among other things, that, in children, there is an inverse relationship between blood-lead level (“BLL”) and IQ. Respondents moved to preclude Dr. Caplan’s opinions and testimony, and for summary judgment. Respondents contended that Dr. C aplan lacked a sufficient factual basis for the opinion that Ms. Oglesby was exposed to lead at the property and that the alleged exposure caused her injuries. In addition, Respondents argued that the methodology Dr. Caplan used to calculate Ms. Oglesb y’s IQ loss was not reliable or generally accepted. After a hearing, conducted rem otely, at which the circuit court simultaneously considered motions to preclude exper t opinions and testimony and motions for summary judgment in Ms. Oglesby’s case and a se cond unrelated case, and a motion

2 See Richard L. Canfield, Charles R. Henderson, Jr., Deborah A. Cory-Slechta, Christopher Cox, Todd A. Jusko, and Bruce P. Lanphe ar, Intellectual Impairment in Children with Blood Lead Concentrations below 10 μg per Deciliter, 348 New Eng. J. of Med. 1517 (Apr. 17, 2003), available at https://www .ncbi.nlm.nih.gov/pmc/articles/ PMC4046839/ [https://perma.cc/ JV55-68C3].

3 See Bruce P. Lanphear, Richard Hornung, Jane Khoury , Kimberly Yolton, Peter Baghurst, David C. Bellinger, Richard L. Canfield, Kim N. Dietrich, Robert Bornschein, Tom Greene, Stephen J. Rothenberg, Herbert L. Needl eman, Lourdes Schnaas, Gail Wasserman, Joseph Graziano, and Russell Roberts, Lo w-Level Environmental Lead Exposure and Children’s Intellectual Function: An I nternational Pooled Analysis, 113 Env’t Health Persps. 894 (July 2005), available at https://www.ncbi.nlm.nih.gov/pmc/ articles/PMC1257652/ [https://perma.cc/8LT6-NZZQ].- 3 -

for summary judgment in a third separate case, the court granted both of Respondents’ motions in Ms. Oglesby’s case. The circuit court f ound that Dr. Caplan lacked a sufficient factual basis for his opinions due to what the cour t described as “factual issues in both of the cases, which [] normally could be presented to a jury” and that, without Dr. Caplan’s testimony as to causation, Ms. Oglesby was unable t o establish a prima facie case of negligence. Ms. Oglesby appealed, 4 and the Appellate Court of Maryland 5 affirmed the judgment of the circuit court. Ms. Oglesby filed a petition for a writ of certiorari , which we granted. After a careful review of the record, we hold that in ruling on the motion to preclude and making determinations as to whether Dr. Caplan’ s opinions had a sufficient factual basis, the circuit court resolved genuine disputes of material fact. We conclude that Dr. Caplan’s opinion regarding Ms. Oglesby’s exposure t o lead at the property being a significant contributing factor to her injuries, ot her than IQ loss, was supported by a sufficient factual basis and admissible, as Dr. Cap lan had more than an adequate supply of data from which to form the opinion and the methodo logy he employed was reliable. As such, the circuit court abused its discretion in gr anting the motion to preclude and in

4 The circuit court granted the motion to preclude an d the motion for summary judgment as to Ms. Oglesby’s claims for negligence and negligent misrepresentation. Ms. Oglesby consented to entry of summary judgment as t o the claim for a violation of the Maryland Consumer Protection Act, so that judgment would be final. On brief in this Court, Ms. Oglesby advises that she appealed the ci rcuit court’s exclusion of Dr. Caplan’s testimony and grant of summary judgment only as to the negligence claim.

5 At the November 8, 2022 general election, the voter s of Maryland ratified a constitutional amendment changing the name of the C ourt of Special Appeals of Maryland to the Appellate Court of Maryland. The name chang e took effect on December 14, 2022.- 4 -

determining that Dr. Caplan’s testimony that Ms. Og lesby’s exposure to lead at the property was a significant contributing factor to h er injuries was inadmissible. We remand the case, however, for further proceeding s consistent with this Court’s holding in Rochkind v. Stevenson, 471 Md. 1, 236 A. 3d 630 (2020), for a determination as to whether the methodology Dr. Caplan employed unde r the Canfield and Lanphear studies reliably supports the conclusion that Ms. Oglesby’s exposure to lead resulted in a loss of approximately 3 to 4 IQ points, should Ms. Oglesby seek to introduce such testimony at

trial. Having concluded that the circuit court abused its discretion in granting the motion to preclude, we hold that the circuit court erred i n granting summary judgment. The circuit court’s ruling—that Ms. Oglesby was unable to prove negligence without Dr. Caplan’s testimony as to causation—was not warranted. Ms. O glesby presented sufficient evidence that the property was a reasonably probable source of her exposure to lead and that the exposure was a significant contributing factor to h er injuries, other than IQ loss, to establish

a prima facie case of negligence. Accordingly, we reverse the j udgment of the Appellate

Court and remand the case to that Court with instru ction to remand the case to the circuit court for trial or further proceedings under Rochki nd, 471 Md. 1, 236 A.3d 630, with respect to Dr. Caplan’s opinion as to IQ loss, shou ld Ms. Oglesby seek to introduce such

evidence at trial.

BACKGROUND Residential History At the outset, we point out that all of the materia l facts concerning Ms. Oglesby’s- 5 -

alleged exposure to lead-based paint—such as whethe r there was lead present at the property at the time Ms. Oglesby lived there; wheth er Ms. Oglesby came into contact with lead at the property through peeling or chipping pa int; and whether she suffered injury due to any such exposure—were disputed in the circuit c ourt. 6 Ms. Oglesby alleges that she suffered lead-based pa int poisoning while residing at 2000 East North Avenue in Baltimore City, Apartment 202, for approximately three years

when she was a child. 7 Ms. Oglesby was born on April 12, 1998. For the first eight months of her life, Ms. Oglesby lived with her mother, Cas ey Powell, at her grandmother’s (Ms. Powell’s mother’s) house on East Jefferson Street. At deposition, Ms. Powell testified that the house on East Jefferson Street was in good cond ition and that she did not recall any issue with peeling or flaking paint. 8

6 The information concerning Ms. Oglesby’s residentia l history set forth in the Background section of the opinion is derived from M s. Oglesby’s complaint, deposition testimony of witnesses, Respondents’ motion to prec lude expert testimony and motion for and memorandum in support of summary judgment, Ms. Oglesby’s response and memorandum in opposition to the motions, and exhibi ts attached to the motions and memoranda.

7 In the complaint, Ms. Oglesby alleged that she was exposed to lead in the common areas of the property as well as in the apartment, and referred to the apartment as “the leased premises.”

8 According to Respondents, shortly after Ms. Oglesby ’s birth, Ms. Powell moved out of the East Jefferson Street address on her own and lived at a different address—706 Milton Avenue. Respondents also allege that in Dec ember 1998, when she applied to live at 2000 East North Avenue, Ms. Powell listed 338 Ma son Court as her prior residence in an application to transfer her Baltimore Gas & Elec tric service to the property. Respondents contend that Dr. Caplan failed to rule out the East Jefferson Street, Milton Avenue, and Mason Court locations as contrib uting to Ms. Oglesby’s first BLL and that multiple sources of exposure to lead may have contributed to her alleged injuries. As we explain below, these contentions, which, in part , constitute factual disputes concerning sources of Ms. Oglesby’s exposure to lead, do not r ender Dr. Caplan’s opinion as to the source and cause of Ms. Oglesby’s injuries inadmiss ible.- 6 -

On December 18, 1998, when Ms. Oglesby was eight mo nths old, she and Ms. Powell moved into 2000 East North Avenue, Apartment 202. 9 Respondents owned and managed the apartment building. At deposition, Ms. Powell testified that the apartment was in poor condition when she moved in, and she di d not do a walk-through with the landlord before signing the lease and receiving a k ey. 10 According to Ms. Powell, when she moved in, she noticed peeling or chipping paint “everywhere” in the building, “[t]hroughout the hallways[, t]he stairwells[, s]om e outdoors[,]” and “[s]ome of [the] apartments ha[d] peeling paint on it.” Ms. Powell testified that the front door of the building and the vestibule inside the back door of the building also contained peeling paint. 11 Ms. Powell testified that she did not see her chi ldren touch or put any peeling paint

9 Ms. Oglesby also had two brothers who lived in the apartment. Ms. Oglesby’s brother Keshar was born in May 1999, and her brothe r Quran was born in December 2000. Ms. Oglesby’s brothers lived in the apartment until the family moved in January or February 2002.

10 According to a Crowninshield Management Corporation “Move-In Move-Out Inspection” form, which is Exhibit 5 to the memoran dum in support of Respondents’ motion for summary judgment, a move-in inspection o f the apartment occurred on December 18, 1998. No deficiencies were noted on t he form, and the form was signed by a representative of Crowninshield Management Corpor ation and purportedly by Ms. Powell.

11 Ms. Oglesby attached as exhibits to the memorandum in support of her response to the motion for summary judgment and motion to pr eclude excerpts of depositions taken in other lead-based paint cases involving Baltimore Schools Associates and 2000 East North Avenue. At a deposition taken in Ikem Ravenell v. Balt. Sch s. Assocs., et al., No. 24-C-16- 007111 (Cir. Ct. Balt. City), Tasha Transou, who li ved in Apartment 103 in the building, testified that the building had paint chipping on a ll of the doors, “chipping paint all falling in the hallway[,]” chipping, flaking paint on the m etal railing along the steps leading up to the building, and that “the paint was chipping and peeling all the way through the hallway when you walked through to get to [her] apartment[. ]” Ms. Transou testified that she was- 7 -

in their mouths, but indicated that Ms. Oglesby may have picked up peeling paint in a hallway, where she played. According to Ms. Powell, although the apartment was in poor condition when she moved in, she did not recall any issue initially wi th peeling or chipping paint inside the apartment. Within six or seven months, though, Ms. Powell noticed peeling paint on the walls and windowsills and in the bathroom of the ap artment, and that the paint in a closet was peeling from moisture. Ms. Powell testified th at, approximately a year after she moved into the apartment, management repainted the buildi ng’s common areas and the doors of the apartments, but the “paint that they put over t he peeling paint started peeling off again.” Ms. Powell testified that, at the time of the repai nting, she asked management to repaint her window, the closet, and other locations inside the apartment, but management repainted only one window inside the apartment. A Crowninshield Management Corporation annual unit inspection report, in an exhibit attached to Ms. Oglesby’s opposition to the motions for summary judgment and to preclude, indicates that, on October 7, 2001, a rep resentative of the company conducted an annual inspection of the apartment and noted that c omponents in every room were unacceptable and needed rehabilitation, including d oors, walls, floors, windows, and the

the last person who lived in Apartment 103 before t he building was shut down due to the poor living conditions. At a deposition taken in connection with another ca se brought against Respondents, Jua’Drek Addison v. Balt. Schs. Assocs., LLP, et al ., No. 24-C-17-004504 (Cir. Ct. Balt. City), Juanita Addison testified that she would bri ng her son with her every day to visit her sister, who lived in the building, and that the bui lding contained peeling paint.- 8 -

bathroom ceiling. 12 Ms. Powell testified that in or around January or February 2002, when Ms. Oglesby was three years and nine or ten months old, after having stayed briefly with her brother in December 2001, the family moved out of the apartment. 13 Ms. Powell testified that the apartment building was being clo sed down and they were told to relocate. 14 It is undisputed that the building was not well mai ntained and that in early 2002, Respondents closed the building rather than make ne cessary repairs. 15

12 Annual unit inspection reports dated October 19, 19 99, and October 27, 2000, which were Exhibits 8 and 9, respectively, to the m emorandum in support of Respondents’ motion for summary judgment, indicated that the com ponents in the apartment were in acceptable condition on those dates.

13 Ms. Powell testified that, in December 2001, after a robbery occurred at the apartment, she and her children, including Ms. Ogle sby, stayed with her brother, who lived in the 2800 block of Lafayette, for “a couple weeks [.]” Ms. Powell testified that she did not know of any issues with peeling paint at her br other’s house while she stayed with him.

14 Ms. Powell also testified that while she and Ms. Og lesby resided at the property, she and her siblings did “weekend swaps[,]” in whic h the adults took turns caring for each other’s children. During the weekend swaps, Ms. Og lesby would spend time at her uncle’s (Ms. Powell’s brother’s) house once or twice a mont h in the 2800 block of Lafayette, and she would also spend time each month at another unc le’s house and her aunt’s house. Respondents contend that the Lafayette residence wa s a source of exposure to lead for Ms. Oglesby, as her uncle brought a lead-based paint ac tion, alleging that his two sons were exposed to lead at the residence. As explained bel ow, this contention, which, in part, constitutes a factual dispute, does not render Dr. Caplan’s opinion as to the source and cause of Ms. Oglesby’s injuries inadmissible.

15 An article from the November 24, 2001 edition of The Baltimore Sun , Vision for dwellings becomes another city housing nightmare by Eric Siegel, was attached as an exhibit to Ms. Oglesby’s memorandum in support of h er opposition to the motion for summary judgment and motion to preclude. According to the article, in a letter to City housing officials in June 2001, the president of Cr owninshield Management Corporation stated that the six Schoolhouse Apartment buildings were “extremely difficult to maintain” and that Crowninshield was unable to manage the bui lding at 2000 East North Avenue to “anyone’s minimum standards.” The article stated t hat, on November 7, 2001, the United States Department of Housing and Urban Development (“HUD”) notified the City’s Housing Authority that it had violated its obligati on to keep the buildings in safe and sanitary condition, that all six buildings were in unacceptable condition, and that the- 9 -

Ms. Powell testified that, beginning in January or February 2002, she and Ms. Oglesby resided at 1713 Lemmon Street. Ms. Powell described the Lemmon Street address as a three-story row house that was “newly renovate d[,]” where “[e]verything was fresh[,]” with “[n]othing peeling[.]” Ms. Powell testified t hat, sometime in the winter of 2003-2004, the family moved from Lemmon Street to a house on M osher Street. According to Ms. Powell, the Mosher Street house had peeling paint i n the basement, where she did not allow her children to go, in a pantry in the kitchen, and “a little bit” in a back bedroom where there had been a roof leak and water damage. Ms. P owell also recalled peeling paint and

dust on the wooden floors of the Mosher Street hous e. In 2005, the family moved from the Mosher Street house, in part because the landlord w ould not make repairs to the property. Ms. Powell testified that, afterward, she and Ms. O glesby lived at a property on Elmora Street followed by a property on North Ellwood. 16 Ms. Oglesby’s BLLs Ms. Oglesby’s BLLs were tested on three occasions b etween 1999 and 2004. A sample of Ms. Oglesby’s blood collected on April 19 , 1999, while Ms. Oglesby resided in the apartment, showed that Ms. Oglesby had a BLL of 2 micrograms per deciliter

building at 2000 East North Avenue, where at least two-thirds of 37 units were vacant, was in the worst shape. According to the article, HUD ordered the Housing Authority to create a plan to restore the properties within 30 days and , 5 days later, Crowninshield issued eviction notices and informed City officials that i t was closing all six buildings.

16 On brief, Respondents contend that Ms. Powell “beli eved” that Ms. Oglesby had an elevated BLL while living on North Ellwood and t hat Ms. Oglesby “believes” her physician determined that she had an elevated BLL i n high school. Respondents assert that, in forming his opinion, Dr. Caplan did not ta ke into account the two subsequent BLLs. Respondents do not identify, however, any BLL test results other than the three described below, which Dr. Caplan relied on.- 10 -

(“μg/dL”). 17 A sample of Ms. Oglesby’s blood collected on Marc h 27, 2002, shortly after she moved out of the apartment, showed that Ms. Ogl esby had a BLL of 5.5 μg/dL. Finally, a sample of Ms. Oglesby’s blood collected on August 20, 2004 showed that Ms. Oglesby had a BLL of 4 μg/dL. The Property: 2000 East North Avenue The building was constructed in 1890 and first serv ed as a schoolhouse in Baltimore City. As of March 1979, lease and development agre ements between the City of Baltimore and Baltimore Schools Associates provided for Balti more Schools Associates to convert six vacant school buildings, including the one at 2 000 East North Avenue, into apartment buildings and to maintain the properties as rental apartments for low-income tenants through 2030. The six buildings became known as th e Schoolhouse Apartments. 18 According to Ms. Oglesby’s response to Respondents’ motions, because the

17 BLLs “are measured in micrograms per deciliter (μg/ dL) of blood” and, “[a]s of 2012, the Centers for Disease Control and Preventio n consider[ed BLLs] greater than 5 μg/dL to be elevated.” Levitas v. Christian, 454 M d. 233, 238 n.3, 164 A.3d 228, 231 n.3 (2017) (citations omitted). As of 2021, the Center s for Disease Control and Prevention “use[d] a blood lead reference value (BLRV) of 3.5 micrograms per deciliter (μg/dL) to identify children with [BLLs] that are higher than most children’s levels.” Centers for Disease Control and Prevention, Blood Lead Reference Value (last reviewed Dec. 2, 2022), https://www.cdc.gov/nceh/lead/data/blood-lead-refer ence-value.htm [https://perma.cc/ 3DXX-YTYR]. See also Centers for Disease Control a nd Prevention, CDC updates blood lead reference value to 3.5 μg/dL (last reviewed Dec. 16, 2022) https://www.cdc.gov/nceh/lead/news/cdc-updates-bloo d-lead-reference-value.html [https://perma.cc/X5B5-94RV] (“On October 28, 2021, CDC updated the blood lead reference value (BLRV) from 5.0 μg/dL to 3.5 μg/dL. ”).

18 The project was subsidized through a $4.1 million l oan from the City, and rents were to be paid by the United States Department of Housing and Urban Development through the City’s Housing Authority under the Sect ion 8 program.- 11 -

building at 2000 East North Avenue was built before 1950 and not certified as lead-free, Respondents registered the building with the Maryla nd Department of the Environment’s Lead Poisoning Prevention Program in February 1995, which demonstrated that the building was not, in fact, lead-free. Ms. Oglesby pointed out that the building received lead-based paint risk reduction certificates, rathe r than lead-free certificates, from the Maryland Department of the Environment on December 4, 1996, June 16, 1998, and January 28, 1999. Records indicate the building at 2000 East North Av enue has been inspected or tested for lead by three different entities on thre e separate occasions, once before Ms. Oglesby’s residency and twice afterward. In 1989, the Baltimore City Health Department issued an “Emergency Violation Notice and Order to Remove Lead Nuisance” for Apartment G-2 in the building after it had been det ermined by the Department that a child who frequented the apartment had “an abnormal” BLL and an inspection of the unit showed that “it contain[ed] lead[-]based paint.” The Depa rtment ordered the removal of lead-based paint from the building’s front exterior doors, fro nt vestibule door and frame, rear exterior doorframes, and west exit doors and drainpipes. On April 13, 2011, Arc Environmental, Inc., a compa ny providing inspection and consulting services, conducted a lead-based paint i nspection of Apartment 203 and other areas of the building. On April 20, 2011, Arc Envi ronmental issued a “Lead-based Paint Survey Report,” concluding that lead-based paint ab ove the Maryland standard was detected on window jambs in the living room and two bedrooms in Apartment 203. Apartment 203 was the only apartment tested by Arc Environmental. Lead-based paint- 12 -

above the Maryland standard was also detected, howe ver, on the first- to second-floor rear stairs baluster and newel post, the first-floor rea r hallway wall, the second-floor hallway window jamb, and the first-to-second floor front st airs window casing. On April 17 and 18, 2012, Green Street Environmenta l, a Maryland-licensed lead inspection contractor, conducted a lead-specific X- ray fluorescence analysis of painted building components at 2000 East North Avenue. On April 20, 2012, Green Street Environmental issued a report, indicating that 84 a reas throughout the building contained lead-based paint. In floor plans attached to the r eport, apartments and other areas such as stairways and hallways are identified in numerical order, starting with “1,” on each floor of the building, and are called “rooms” in the repo rt. In other words, in the report, former apartments are not identified by the numbers that t hey had when occupied by residents. 19 On the second floor, there are 12 rooms identified by numbers 1 through 12. Two of the rooms are stairways: room 1 and 7. Room 2 i s a hallway. Room 8 is a large area bearing a notation that part of it is destroyed and inaccessible. The remaining rooms on the second floor are rooms 3, 4, 5, 6, 9, 10, 11, a nd 12. Green Street Environmental provided the following floor plan for the second fl oor of the building:

19 In a Rental Property Registration form for the Mary land Department of the Environment’s Lead Poisoning Prevention Program com pleted in February 1995, the apartment units in 2000 East North Avenue were iden tified, at that time, by the following numbers: G1 through G5, 101 through 114, 201 throug h 214, and 301 through 304. According to the information on the form, there wer e apartments on the ground floor, first floor, second floor, and third floor of the buildin g.- 13 -

According to the report, rooms that had been apartm ents on both the first and second floors of the building contained lead-based paint o n windowsills, window casings, and window troughs in living rooms and bedrooms, on liv ing room, bedroom, and bathroom- 14 -

walls and wainscots, and on kitchen and apartment s torage room walls. With respect to the second floor, the report states that locations in rooms 3, 4, 5, 6, 7, 9, and 11 tested positive for lead-based paint. The only rooms on t he second floor that did not test positive for lead-based paint were rooms 1 (a stairway), 2 ( a hallway), 8 (a large area marked partly destroyed and inaccessible), and rooms 10 and 12 (p otentially former apartments). In the report, Green Street Environmental stated that area s of the building that were not accessible for inspection “likely contain[ed] components that would test positive for Lead[-]Based

Paint.” Dr. Caplan’s Report and Deposition In a report dated December 26, 2019, Dr. Caplan con cluded that Ms. Oglesby’s “likely exposure to lead at 2000 E. North Ave is a significant contributing factor to her lead intoxication” and to her impairments or “difficulti es” described in the report. Dr. Caplan concluded that Ms. Oglesby “was exposed to environm ental lead and had academic and behavioral problems in school, attentional issues, and symptoms of depression.” Dr. Caplan explained that Dr. Hawkins-Heitt performed a neuropsychological evaluation of Ms. Oglesby on January 28, 2019 and determined that her areas of impairment included “visual and working memory, visual attention speed, visual motor integration and copying skills, encoding and recognition of verbal informat ion, recall of complex visual information, and categorical verbal fluency,” and t hat she had a full scale IQ score of 80, which is “at the lowest end of the low average rang e.” Dr. Caplan reported that, “according to the United States Environmental Protection Agenc y, the American Academy of Pediatrics, the Maryland Department of the Environm ent, and the World Health- 15 -

Organization[,]” “[l]ead is a causal or likely caus al factor” for academic and behavioral problems, attentional issues, and symptoms of depre ssion. Dr. Caplan explained that Mr. Lieberman performed a n employability assessment of Ms. Oglesby on September 13, 2019, and determine d she performed low or below average in areas related to word knowledge, languag e arts, and verbal reasoning, and that she would be “classified as a Cognitively Disabled female by the American Community Survey of the U.S. Census Bureau.” In addition to his opinion concerning her other impairments, Dr. Caplan concluded that, “[e]xtrapol ating from the data of Canfield and Lanphear, an IQ deficit of about 3 to 4 IQ points c an be attributed to [Ms. Oglesby’s] lead exposure.” In the report, prior to setting forth his opinion a bout Ms. Oglesby’s exposure to lead at the property being a significant contributing fa ctor to her alleged injuries, Dr. Caplan discussed information concerning Ms. Oglesby’s resi dential history and the condition of 2000 East North Avenue. Dr. Caplan reported that M s. Oglesby lived at 2000 East North Avenue from December 1998 until late 2001 or early 2002. Dr. Caplan noted that the building at 2000 East North Avenue was built before 1950 and had “multiple inspections indicating the presence of lead based paint.” Dr. Caplan reported that on October 5, 1989, the Baltimore City Health Department issued an emer gency lead paint violation notice; on April 13, 2011, an inspection performed by Arc Envi ronmental found multiple areas containing lead; and on April 17 and 18, 2012, and again from June 30 to July 3, 2014, Green Street Environmental analyzed the building an d found multiple areas containing lead-based paint.- 16 -

Based on his review of the records provided to him, Dr. Caplan concluded that lead paint “was accessible” to Ms. Oglesby “during her t enancy” at the building. Dr. Caplan explained that Ms. Powell “described the apartment as being in poor condition with peeling and chipping paint throughout the hallways and stai rwells as well as from the doors” and that paint in the apartment “began to peel about si x months after she moved in.” Dr. Caplan noted that some repainting was performed in the bui lding and on one window in Ms. Oglesby’s apartment; however, chipping and peeling of the paint occurred after the repainting. Dr. Caplan observed that the October 7 , 2001 annual inspection for the apartment “indicated multiple rooms needing rehabil itation.” Dr. Caplan also noted that “multiple other children who lived at 2000 E. North Ave from the late 1980’s to the early

2000’s suffered from lead intoxication.” As to other properties, Dr. Caplan stated that, in late 2001 or 2002, Ms. Oglesby moved to the Lafayette location for a few weeks bef ore moving to Lemmon Street, and that both of those properties were reported to have “had no peeling paint.” Dr. Caplan indicated that Ms. Oglesby had “no significant visitations to other properties” during the time that

she resided at 2000 East North Avenue. At a deposition taken on February 25, 2020, Dr. Cap lan verified that, prior to completing his report, he reviewed 24 items pertain ing to the case, including the depositions of Ms. Powell and Ms. Oglesby, 20 and that he reviewed an additional 5 items

20 The items that Dr. Caplan reviewed before completin g his report included the following documents pertaining to Ms. Oglesby: Mary land Department of the Environment records; Maryland Department of Health and Mental H ygiene (now the Maryland- 17 -

before deposition. 21 Dr. Caplan testified that his opinion was that Ms . Oglesby was exposed to lead at 2000 East North Avenue, that she had suffered “sequelae from all the exposure to lead that she’s had[,]” and that she ha d incurred an IQ deficit of approximately 3 to 4 points, i.e. , that Ms. Oglesby’s IQ score would have been 83 or 84. 22

Department of Health) records; University of Maryla nd Medical Center records; Total Health Care medical records totaling 30 pages; Dr. Hawkins-Heitt’s report; a report from Mr. Lieberman concerning Ms. Oglesby’s vocational c apabilities, limitations, and future earning potential; and a report from Michael A. Con te, Ph.D., an expert in the areas of economics and forensic economics designated by Ms. Oglesby. In addition, Dr. Caplan reviewed, among other things: Ms. Powell’s tenant f ile totaling 114 pages; the “Property Card” for 2000 East North Avenue; Green Street Envi ronmental’s report; Arc Environmental’s report; Maryland Department of the Environment records concerning 2000 East North Avenue totaling 21 pages; records o f the Maryland Department of the Environment’s Lead Poisoning Prevention Program for 2000 East North Avenue totaling 43 pages; Maryland Department of the Environment in spection certificates for Unit 208 of 2000 East North Avenue totaling 25 pages; and Maryl and Department of the Environment records concerning Ikem Ravenell and 2000 East Nort h Avenue totaling 28 pages.

21 The 5 additional items reviewed by Dr. Caplan prior to deposition were: a psychological evaluation report from Neil Hoffman, Ph.D.; Dr. Hoffman’s deposition and exhibits; Mr. Lieberman’s deposition and exhibits; Dr. Conte’s deposition; and his own report on Ms. Oglesby.

22 The deposition transcript shows that the following exchange occurred between Respondents’ counsel and Dr. Caplan as to Ms. Ogles by’s IQ loss: [RESPONDENTS’ COUNSEL:] Going on to the next paragr aph you referenced the testing of [Ms. Oglesby] with an IQ score of 80 and you agree that an IQ score of 80 is in the low average range? [DR. CAPLAN:] It’s the lowest number in the low ave rage range, yes. [RESPONDENTS’ COUNSEL:] Am I correct that the range for low average is 80 to 89? [DR. CAPLAN:] Correct. [RESPONDENTS’ COUNSEL:] So it is your opinion that after the alleged lead exposure her IQ would have been 83 or 84?- 18 -

Dr. Caplan testified that he reviewed “data from La nphear in his pooled analysis as

well as Canfield from a 2003 article” and that he “ extrapolated from the data that they put forth” and determined a result. Although Dr. Capla n did not specifically testify to this, his

calculations demonstrate that he determined that th e Lanphear and Canfield studies indicate that every 1 μg/dL in a BLL leads to a loss of 0.62 or 0.74 IQ points, respectively. Dr. Caplan testified that he calculated, based on the a verage of Ms. Oglesby’s BLLs, 3.8 μg/dL, 23 that Ms. Oglesby would have lost approximately 2.4 (3.8 times 0.62) IQ points according to the Lanphear study or 2.8 (3.8 times 0 .74) IQ points according to the Canfield study. Dr. Caplan calculated that, based on Ms. Oglesby’s highest or peak BLL, 5.5 μg/dL, she would have lost approximately 3.4 (5.5 times 0. 62) or 4.1 (5.5 times 0.74) IQ points according to the Lanphear and Canfield studies, res pectively. In sum, Dr. Caplan used Ms. Oglesby’s average and peak BLLs, and concluded that , under the Lanphear study, multiplied by a factor of 0.62, her loss of IQ poin ts was 2.4 to 3.4 points, and that, under the Canfield study, multiplied by a factor of 0.74, her loss of IQ points was 2.8 to 4.1 points. Dr. Caplan rounded the numbers to 2 to 3 points and 3 to 4 points, respectively. Dr. Caplan testified that Ms. Oglesby’s BLL of 5.5 μg/dL was pertinent to the East

[DR. CAPLAN:] Approximately. It is clear that, in this exchange, Dr. Caplan conf irmed his opinion concerning an IQ loss of 3 to 4 points.

23 The average of the results of Ms. Oglesby’s three B LL tests ( i.e. , 2, 5.5, and 4 μg/dL) was approximately 3.8 μg/dL.- 19 -

North Avenue address, as her blood was tested two t o three months after she moved out of the building. Dr. Caplan explained that Ms. Oglesb y moved “to a place that did not have peeling and chipping paint” and that it was “very l ikely” that the East North Avenue address was responsible for her BLL of 5.5 μg/dL. Dr. Caplan testified that Ms. Og lesby’s BLL “might have been even higher two months earlier and then started to fall during those

two to three months that she left.” When asked abo ut Ms. Oglesby’s IQ loss, Dr. Caplan testified that, even with a three-point IQ loss, go ing from an IQ of 83 to 80, Ms. Oglesby’s “neuro executive functioning has been affected” and she would be “functioning at a little bit lower level[.]” The Circuit Court’s Ruling On April 29, 2020, the circuit court conducted a he aring on Respondents’ motions. In a single hearing, the circuit court heard argume nt on motions to preclude expert opinions and testimony and motions for summary judgment in M s. Oglesby’s case and a second unrelated case, and a motion for summary judgment i n a third unrelated case. In all three cases, plaintiffs who were represented by Ms. Ogles by’s counsel had sued Respondents, claiming injuries due to lead-based paint exposure at different locations, 2000 East North Avenue, 249 Aisquith Street, and 511 South Bond Str eet. See Tybria Cheley v. Balt. Schs. Assocs., et al., No. 24-C-18-000313 (Cir. Ct. Balt. City); Dwanshayne Johnson v. Balt. Schs. Assocs., et al., No. 24-C-18-001928 (Cir. Ct. Balt. City). At the hearing, the circuit court granted the motions to preclude Dr. Caplan’s opinions and testimony in Ms. Oglesby’s case and in Johnson. In granting the motions, the circuit court ruled on Ms. Oglesby’s case and the- 20 -

Johnson case together. The circuit court began by stating: “As it relates to the two Motions to Preclude the Opinions and Testimony of Dr. Capla n, the Court has had an opportunity to review the pleadings.” The circuit court observ ed that Levitas v. Christian, 454 Md. 233, 164 A.3d 228 (2017) shows that “a qualified ex pert can rely on other research and can rely on another doctor’s report[.]” The circuit co urt stated that Levitas was different, though, ruling:

However, the difference here, in Levitas there was -- the issue in Levitas was the expert’s use of -- well, a couple t hings. One is using -- relying on a report of another doctor, and also rel ying on a particular type of research, which I think was Lanphear in that case, and there had been some question, I think about it. But the bottom line was the Court found a qualifie d expert can rely on other research and can rely on another doctor’s rep ort, and things like that. That’s different from what we have in this case. What we have in this case is there -- it’s the oppo site of relying on the research that was cited by the expert in this parti cular case. So at the outset let me say Rule 5-702 allows expert testimony to be admitted. There are three factors that have to be satisfied, the third and most relevant here is whether there is a sufficient factual basis to supp ort the expert testimony. For the most part, the case law will say that once you have a qualified expert their -- the factual basis generally will go before a jury because it is up to a jury to weigh the credibility of the expert . And that is generally based on what is it -- whatever it is that they use to re ach their conclusions in their opinions. It’s proper for cross-examination and th ey jury can decide, “Well, you know, he looked today, [sic] but he didn’t look at B, this doesn’t, you know.” The jury gets the opportunity then to evalu ate that credibility. The problem that we have in this case is that there are a couple of things, particularly as it relates to a factual bas is. Again, some of what is being argued by Defendants could be for the jury. But then there are other things, particularly like in the Johnson case, I me an, it’s undisputed that he - - some of what he relied on was just incorrect. Th e facts -- they -- it was just incorrect information that he relied on. And also, in both of the cases he does not use all of the available blood level -- blood lead level information in formulatin g his IQ loss opinions. And then notwithstanding that, he uses methodology that has not been shown to be accepted. As a matter of fact, it’s directly an d expressly contradictory to that which he actually identifies as generally acce pted research in the field.- 21 -

And the problem that this Court has, he offers no e xplanation as to why he did it. He offered no support for using that -- th ose calculations in that way. And also again, there’s nothing to support that -- the way that he chose to interpret, I guess if you will, for the methodol ogy that he chose in this case is acceptable, and also not contrary to that, which again, he cited. So that combined with the fact that there are some issues as it relates to the facts that he uses before he employs this me thodology I think makes this a situation for which the Court can find that his opinion and his testimony is unreliable and shouldn’t be presented to a jury. And so for those reasons in each of the two cases, Ms. Oglesby and Mr. Johnson, the Court will grant the Motion to Pre clude the Opinion Testimony of the Witness, Dr. Steven Caplan. Ms. Oglesby’s counsel immediately asked the circuit court for clarification of its ruling, pointing out that there were two separate c ases. Counsel asked: “I just want to make sure that the record is clear when you stated that Dr. Caplan, you said that it’s undisputed that some of what he relies on is incorrect, and yo u said that specific to Johnson. That is not specific in the Oglesby case; is that correct?” The circuit court responded:

So specific to Johnson when I said as it relates to incorrect information, based on what was presented by the def endant. Although, the Court also finds that -- I think the defense, just to be clear, has presented -- what’s the word I’m trying to use? That there are issues, if you will, with the facts and the information that was gathered, and ho w it was gathered, and who he spoke to, and who he didn’t speak to. I think he’s present -- the defense has presented i ssues, and they are more typical and would more likely, as it relates t o both case [sic]. And those would more likely be placed in front of a jury, whi ch is very different from the completely incorrect information. But just to be clear, the basis of the Court’s ruli ng is not only when you combine those issues with the issue of the use of the methodology, the Court believes that together that makes his testimo ny and opinion inherently unreliable. And so it is a combination of factual issues and the expert’s methodology for both cases. But the incorrect info rmation was presented to the Court, for what I believe is undisputed incorre ct information, in the Johnson case. That’s the best I can give you on th at. Later, during argument on the motion for summary ju dgment, Ms. Oglesby’s- 22 -

counsel sought clarification as to whether Dr. Capl an would be permitted to render an opinion that “2000 East North Avenue was a substant ial contributing factor in brin[g]ing about” Ms. Oglesby’s BLLs. The circuit court responded unequivocally that Dr. Caplan was “precluded from giving any opinion testimony, a nd that is more so because of the factual issues in both of the cases, which again, n ormally could be presented to a jury.” Specifically, the circuit court stated:

So in this particular instance, the Court is orderi ng that the doctor be precluded from giving any opinion testimony, and th at is more so because of the factual issues in both of the cases, which agai n, normally could be presented to a jury. And in this particular case, if we were to parse it out, we could, but I don’t believe that is appropriate. Or if there is a way to sort of parse out the two. And so this Court’s ruling is t hat the doctor give no opinion testimony based on the information gathered in these two cases. Ms. Oglesby’s counsel again sought clarification an d the following occurred: THE COURT: Okay. Well, I don’t know how to be any more clear. In each of the two cases, exclusive of the other, the Court made findings that were a combination of problems with the facts, as well as problems with the methodology. And the Court, in either case, in bot h cases, and separately in each case, is finding that the issues with the fact s are not going to be parsed out separately for him to give opinion testimony on other things. The Court has ruled that he’s not to give opinion testimony in either of the cases at all. That’s the best I can give yo u for the record. So with him not giving -- [MS. OGLESBY’S COUNSEL]: Okay. Can -- can you plea se -- THE COURT: -- opinion testimony -- [MS. OGLESBY’S COUNSEL]: -- for the -- THE COURT: -- I would ask that you proceed to your defense of the summary judgment please. [MS. OGLESBY’S COUNSEL]: Okay. There has been no - - for [Ms.] Oglesby there’s been no issue regarding any incorre ct facts assumed by Dr.- 23 -

Caplan. I think that was an issue only addressed b y [Respondents’ counsel] in the [] Johnson matter, as far as the visitation period. However, just for the record, it is undisputed that [Ms.] Oglesby was at Apartment 202 of 2000 East North Avenue from Dec ember 1998 through December 2001. It is undisputed that lead was foun d inside 2000 East North Avenue subsequent to the ownership and management b y Defendants of these properties. It’s undisputed that there’s a B altimore City Health Department violation notice that found lead-based p aint in 1989. That there was -- ARC Environmental found lead in the unit of 203. The lead was found throughout 2012 Green Street Environmental. At the conclusion of the hearing, the circuit court granted the motion for summary judgment as to the negligence claim in Ms. Oglesby’ s case, concluding that Ms. Oglesby could not prove negligence without expert testimony on causation. On the same day, the circuit court issued orders, stating in both orders that the motions were granted “for the reasons stated on the record[.]” Ms. Oglesby filed a motion to alter or amend, or in the alternative for reconsideration of, the circuit court’s orders, whi ch the circuit court denied. Ms. Oglesby filed a notice of appeal.

Opinion of the Appellate Court of Maryland On August 9, 2022, the Appellate Court of Maryland affirmed the circuit court’s judgment, holding that the circuit court did not ab use its discretion in excluding Dr. Caplan’s testimony or err in granting summary judgm ent. See Jamaiya Oglesby v. Balt. Sch. Assocs., et al., No. 0130, Sept. Term, 2021, 2 022 WL 3211044, at *8 (App. Ct. Md. Aug. 9, 2022). The Appellate Court explained that the case involved three areas of disputed facts: (1) whether there was any lead-based paint a t 2000 East North Avenue at the relevant time, (2) whether Ms. Oglesby was exposed to any le ad that may have been present at the- 24 -

building through contact with deteriorated paint, a nd (3) whether Ms. Oglesby incurred any injury from exposure to lead while living at th e building. See id. at *4-5. According to the Appellate Court, the circuit court found the disputed data to be inadequate to form the basis of Dr. Caplan’s opinions and, as a result , excluded his expert testimony. See id. at *5. The Appellate Court stated: Given the disputed nature of the evidence regarding the presence of lead in Apartment 202, the disputed nature of the evidence regarding Oglesby’s exposure to peeling paint, and the disputed nature of the evidence regarding any injury suffered as a result—combined with our d eferential standard of review based on Levitas , Rochkind II , and Matthews . . . —however, we cannot say that the circuit court abused its broad discretion in finding that Dr. Caplan lacked an adequate supply of data. Oglesby, 2022 WL 3211044, at *5 (cleaned up). In r eaching its conclusion, the Appellate Court stated: “[O]ur view is that these disputes ma de for a close question.” Id. at *5. With respect to Dr. Caplan’s opinion concerning Ms. Oglesby’s IQ loss, the Appellate Court explained that the Canfield and Lan phear studies have been frequently relied upon in previous lead p aint cases, and Maryland courts have repeatedly held that a properly qualifi ed expert witness can rely on the Lanphear Study methodology, as well as other accepted scientific research, as a factual basis for an opinion that a plaintiff’s elevated [BLLs] caused the loss of a specific number of IQ points. Id. at *6 (cleaned up). The Appellate Court stated that the circuit court’s “quarrel” with Dr. Caplan’s methodology was not that he relied on the studies, but that he had used them in a way that was not generally accepted and he had “offered no explanation for his methodology.” Id. (cleaned up). The Appellate Cou rt concluded that, given the deferential abuse of discretion standard of review, the circuit court was within the bounds of its discretion in finding Dr. Caplan’s methodology for calculation of Ms. Oglesby’s IQ loss- 25 -

unreliable. See id. at *7. The Appellate Court co ncluded that the circuit court did not err in granting summary judgment because, without Dr. C aplan’s testimony, Ms. Oglesby

could not make a prima facie case of negligence, as she could not connect her e xposure to lead at 2000 East North Avenue to her alleged impai rments. See id. at *8.

Petition for a Writ of Certiorari On September 6, 2022, Ms. Oglesby petitioned for a writ of certiorari , raising the following four issues:

l. Did the trial court abuse its discretion when it took factual issues away from the jury and resolved genuine disputes of mate rial fact by ruling that Petitioner’s medical expert lacked an adequate supp ly of data to opine as to the source and source causation of Petitioner’s lea d exposure, when there was substantial evidence for a jury to evaluate, includ ing direct evidence of lead at the subject property, evidence of numerous areas of deteriorated paint, evidence that Petitioner lived in the subject prope rty for three years and was exposed to and ingested lead resulting in her eleva ted [BLLs] and injury?

2. Did the trial court abuse its discretion when it took factual issues away from the jury and resolved genuine disputes of mate rial fact by ruling that Petitioner’s medical expert’s opinion regarding Pet itioner’s IQ loss was inadmissible, when Petitioner’s medical expert reli ed on studies that Maryland courts have repeatedly sanctioned? 3. Did the trial court err when it granted summary judgment after resolving genuine disputes of material fact related to the expert witness’ source, source causation and IQ loss opinions and e xcluded Petitioner’s expert witness from testifying entirely when the ju ry could make the source determination and the expert had rendered numerous other opinions wherein jury could have found that Petitioner was injured f rom her exposure to and ingestion of lead? 4. Did the [Appellate] Court [] err in holding that the trial court did not abuse its discretion when it acted as the jury, ina ppropriately resolved genuine disputes of material facts and excluded the testimony of Petitioner’s expert witness in its entirety and that the trial c ourt did not err in subsequently granting summary judgment?- 26 -

On November 18, 2022, we granted the petition. See Oglesby v. Balt. Sch. Assocs., 482 Md. 142, 285 A.3d 848 (2022).

DISCUSSION

Standard of Review This case involves a challenge to the admissibility of expert opinion under Maryland Rule 5-702(3) and Frye-Reed that originated before the issuance of Rochkind, 471 Md. 1, 236 A.3d 630. In Rochkind, id. at 5, 236 A.3d at 6 33, this Court discontinued use of the “general acceptance” standard for admissibility of expert testimony set forth in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923) and Ree d v. State, 283 Md. 374, 391 A.2d 364 (1978) and adopted the standard set forth in Dauber t v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993) and its progeny. Before Rochkind, appellate courts reviewed a trial court’s decision as to the admissibility of expert testimony under two differe nt standards of review, with a trial court’s determinations under Frye-Reed reviewed de novo and a trial court’s determinations under Maryland Rule 5-702 reviewed f or abuse of discretion. See Rochkind, 471 Md. at 37, 236 A.3d at 651. After Ro chkind, id. at 37, 236 A.3d at 651, this

Court reviews a trial court’s decision to admit or exclude expert opinion for an abuse of

discretion. This Court has described an abuse of d iscretion as occurring “where no reasonable person would take the view adopted by th e trial court[,]” Md. Bd. of Physicians v. Geier, 451 Md. 526, 544, 154 A.3d 1211, 1221 (20 17) (cleaned up), or when “the decision under consideration [is] well removed from any center mark imagined by the- 27 -

reviewing court and beyond the fringe of what that court deems minimally acceptable[,]” Wilson v. John Crane, Inc., 385 Md. 185, 199, 876 A .2d 1077, 1084 (2005) (cleaned up). “An appellate court reviews without deference a tri al court’s grant of a motion for summary judgment, reviews the record in the light m ost favorable to the nonmoving party, and construes any reasonable inferences that may be drawn from the facts against the moving party.” State v. Rovin, 472 Md. 317, 341, 2 46 A.3d 1190, 1204 (2021) (cleaned up). Summary judgment is appropriate where “there is no genuine dispute as to any material fact and [] the [moving] party is entitled to judgment as a matter of law.” Md. R. 2-501(a). Admission of Expert Testimony Generally Maryland Rule 5-702 provides that “[e]xpert testimo ny may be admitted, in the form of an opinion or otherwise, if the court determines that the testimony will assist the trier of

fact to understand the evidence or to determine a f act in issue.” In making that determination, the trial court must determine: “(1) whether the witness is qualified as an expert by knowledge, skill, experience, training, o r education, (2) the appropriateness of the expert testimony on the particular subject, and (3) whether a sufficient factual basis exists to support the expert testimony.” Md. R. 5- 702 (paragraph breaks omitted). The third factor, the existence of a sufficient fac tual basis, has been interpreted as encompassing two sub-factors—whether the expert had an adequate supply of data and whether the expert used a methodology that was reli able. See Sugarman v. Liles, 460 Md. 396, 415, 190 A.3d 344, 354 (2018); Rochkind, 471 M d. at 22, 236 A.3d at 642. Absent either sub-factor, an expert’s opinion is inadmissi ble. See Rochkind, 471 Md. at 22, 236- 28 -

A.3d at 642. We have held that, to satisfy the req uirement of a reliable methodology, “an expert opinion must provide a sound reasoning proce ss for inducing its conclusion from the factual data and must have an adequate theory o r rational explanation of how the factual data led to the expert’s conclusion.” Sugarman, 46 0 Md. at 415, 190 A.3d at 355 (citation omitted). In addition, in determining whether an expert has a sufficient factual basis to offer an opinion, a court may consider whether there is t oo great an analytical gap between the data relied upon and the opinion proffered. See Ro chkind v. Stevenson, 454 Md. 277, 289, 164 A.3d 254, 261 (2017). The data or information upon which an expert relies must provide factual support for the opinions reached. See Sugarman, 460 Md. at 427, 190 A.3d at 362 (“To bridge the analytical gap, an expert’s testimony must have a sufficient factual foundation. It is permissible for an expert to rea sonably extrapolate from existing data provided that a sufficient factual basis for that o pinion exists.” (Citations omitted)). But testimony may not be the ipse dixit conclusion of the expert. See id. at 415, 190 A.3 d at 355 (“Conclusory or ipse dixit assertions are not helpful—an expert must be able to articulate a reliable methodology for how [the expe rt] reached [the] conclusion.” (Cleaned up)). Also, pursuant to Maryland Rule 5-703(a), “[ a]n expert may base an opinion on facts or data in the case that the expert has been made a ware of or personally observed.”

I. The Factual Basis for Dr. Caplan’s Opinion Ms. Oglesby contends that, in excluding Dr. Caplan’ s testimony, the circuit court abused its discretion by concluding that Dr. Caplan relied on incorrect information or that there were problems with the facts Dr. Caplan relie d on, and in doing so resolved genuine- 29 -

issues of disputed fact in favor of Respondents. M s. Oglesby argues that the information that Dr. Caplan relied on was not incorrect, but ra ther was disputed and consisted of facts that, if believed by the jury, provided a sufficien t factual basis for Dr. Caplan’s testimony. Respondents contend that the circuit court properly excluded Dr. Caplan’s testimony because, in their view, Dr. Caplan’s opin ions were based on “limited” information provided by Ms. Oglesby’s counsel and, therefore, lacked a sufficient factual foundation. Respondents argue that Dr. Caplan fail ed to consider other potential sources of exposure to lead-based paint for Ms. Oglesby and merely assumed that Ms. Oglesby was exposed to lead at the property. Respondents maint ain that the circuit court did not reject the accuracy of information that Dr. Caplan relied on, but rather concluded that Dr. Caplan did not have an adequate supply of data for his opi nions. For two reasons, we agree with Ms. Oglesby that the circuit court abused its discretion in excluding Dr. Caplan’s testimony: (1) the record demonstrates that the circuit court impermissibly resolved issues of disputed fac t in excluding Dr. Caplan’s opinion; and (2) Dr. Caplan’s opinion with respect to causat ion (other than as to Ms. Oglesby’s IQ loss) was supported by a sufficient factual basis.

A. The Circuit Court Resolved Disputed Issues of Fa ct

The circuit court abused its discretion in excludin g Dr. Caplan’s testimony based on

its assessment that there were factual issues in th e case, which “normally could be presented to a jury[,]” but which in its view rende red the testimony inadmissible. In Frankel v. Deane, 480 Md. 682, 703-04, 281 A.3d 692 , 705 (2022), we recently held that the trial court erred in precluding an expert’s tes timony and concluded that the trial court- 30 -

“improperly took sides in a credibility contest bet ween” the defendants on one hand and the plaintiff on the other hand and “impermissibly gave” the defendants “the benefit of favorable inferences drawn from evidence susceptibl e to more than one interpretation.” In discussing whether a sufficient factual basis exist ed to support expert testimony under Maryland Rule 5-702(3), we explained that the factu al basis for an expert’s opinion may “come from facts obtained from the expert’s first-h and knowledge, facts obtained from the testimony of others, and facts related to an expert through the use of hypothetical questions.” Id. at 700, 281 A.3d at 703 (cleaned u p). We stated that “experts are permitted to express an opinion based upon facts assumed but not in evidence when the question is asked, if such facts are later proved in the case.” Id. at 700-01, 281 A.3d at 703 (cleaned up). Notably, “[t]his applies to disputed facts as well.” Id. at 701, 281 A.3d at 703. In so concluding, we explained that, in Kruszewski v. Hol z, 265 Md. 434, 445, 290 A.2d 534, 540 (1972), we stated: [T]he proper way to submit a hypothetical question is to ask the witness to presume the truth of certain facts as if they were not the subject of dispute. These may still be contested in actuality but the i nquiry is proper as long as there is evidentiary support for the facts which th e expert is told to assume the veracity of and evaluate in rendering his opini on. Of course, any assumption made must be grounded on a fair summatio n of the material facts in evidence and those material facts must be suffic ient in scope for the witness to formulate a rational opinion. In such a situation the jury is aware of the premise upon which the opinion is based and can determine whether that assumption was valid. If it is not, the opini on of the expert is disregarded. Frankel, 480 Md. at 701, 281 A.3d at 703-04. 24

24 Ms. Oglesby contends that Parkway Neuroscience & Sp ine Inst., LLC v. Katz,- 31 -

In this case, the record demonstrates that, in ruli ng that Dr. Caplan did not have an adequate factual basis for his opinion, the circuit court resolved disputed issues of fact.

The circuit court expressly ruled that Dr. Caplan was “ precluded from giving any opinion testimony, and that is more so because of the factu al issues” that could normally go to a jury. In addition, the circuit court determined th at information Dr. Caplan relied on was “incorrect[.]” We are aware that Respondents contend that the circuit court excluded Dr. Caplan’s opinions “not because it found [Respondent s’] evidence more credible than [Ms.] Oglesby’s evidence,” but because it determined that the evidence upon which Dr. Caplan relied was “limited” or insufficient under Maryland Rule 5-702(3). We are not persuaded, however, by Respondents’ explanation of what the ci rcuit court meant in ruling that Dr. Caplan relied on “incorrect information” and in fin ding that there were facts that could normally be submitted to the jury but that would no t be in this case. The circuit court’s ruling can be viewed in three p arts: its initial ruling and its responses to Ms. Oglesby’s counsel’s two requests f or clarification. In initially ruling that Dr. Caplan relied on incorrect information and that there were issues with the facts, the circuit court did not explain what it meant, identi fy what the incorrect information was or factual issues were, or state whether the finding a bout incorrect information applied to both

Abosch, Windesheim, Gershman & Freedman, P.A., 255 Md. App. 596, 283 A.3d 753 (2022), cert. granted, 482 Md. 534, 288 A.3d 1231 ( 2023) presents a similar issue involving a trial court having resolved issues of disputed fa ct in excluding expert testimony. This Court granted certiorari , and heard oral argument in Katz, Abosch, Windeshe im, Gershman & Freedman, P.A., and Mark E. Rapson v. Pa rkway Neuroscience and Spine Inst., LLC, No. 30, Sept. Term, 2022, on May 4, 202 3. Because Katz is pending, we will not comment on the case.- 32 -

Ms. Oglesby’s case and Johnson’s, just Johnson’s, o r just Ms. Oglesby’s case, or to only Dr. Caplan’s opinion concerning IQ loss or to all o f his opinions. The most specific

reference to what the circuit court deemed the fact ual issues to be was the court’s statement that, in both of the cases, Dr. Caplan had not used all available BLLs. Yet, in this case, Dr. Caplan’s report and deposition testimony show that he considered each of the three BLLs

available in the record. The circuit court’s obser vation lends itself to the conclusion that, as to Ms. Oglesby’s case, the circuit court resolv ed what appeared to be a dispute of fact between the parties—whether Ms. Oglesby had other o r higher BLL results later in her life

that were not included in the record. Due to the n ature of the circuit court’s initial ruling, Ms. Oglesby’s counsel immediately sought clarificat ion and pointed out that there were two separate cases. When Ms. Oglesby’s counsel sought clarification as to whether the circuit court’s statement about incorrect information applied to th e Johnson case and not Ms. Oglesby’s case, the circuit court compounded the confusion by responding, among other things, that the defense had presented issues “as it relates to both case[s]” and “those would more likely be placed in front of a jury, which is very differe nt from the completely incorrect information.” The circuit court stated that, for b oth cases, “it is a combination of factual issues and the expert’s methodology[,]” “[b]ut the incorrect information was presented to the Court, for what I believe is undisputed incorre ct information, in the Johnson case.” Conceivably, the circuit court’s response might som ehow lend itself to the interpretation, as Respondents allege, that the cir cuit court intended to rule that Dr. Caplan relied on incorrect information only in the Johnson case and not in Ms. Oglesby’s case.- 33 -

But, another interpretation of the circuit court’s ruling is that the court intended to rule that Dr. Caplan relied on incorrect information in both cases and on “undisputed” incorrect information in Johnson’s case. This was not, howev er, the last explanation given by the circuit court in response to a request for clarific ation. Later, during argument on the motion for summary ju dgment, when Ms. Oglesby’s counsel sought clarification as to whether Dr. Capl an would be permitted to render an opinion that 2000 East North Avenue was a substanti al contributing factor to Ms. Oglesby’s BLLs, the circuit court responded that Dr . Caplan would be precluded from giving any opinion testimony whatsoever “because of the factual issues in both of the cases, which again, normally could be presented to a jury. ” With this response, the court left no room to doubt that its ruling that there were issue s with the facts that would normally go to the jury applied to both Ms. Oglesby’s case and Joh nson’s. The circuit court stated that in Johnson and this case, “exclusive of the other,” th e court had “made findings that were a combination of problems with the facts, as well as problems with the methodology.” The circuit court once more refused to identify or desc ribe the factual problems that in its view precluded Dr. Caplan’s testimony. Instead, the cir cuit court stated that, “in either case, in both cases, and separately in each case,” it was “f inding that the issues with the facts are not going to be parsed out separately for him to gi ve opinion testimony on other things.” In the end, what can be gleaned from the circuit co urt’s ruling is that it determined that there were factual issues that could normally go to the jury, but would not in this case. Because the circuit court declined to explain or “p arse” what the issues with the facts were, the court did not expressly identify the factual pr oblems or how it resolved them. Implicit- 34 -

in the circuit court’s decision to exclude Dr. Capl an’s testimony in its entirety, based on issues with the facts, instead of only his testimon y concerning Ms. Oglesby’s IQ loss, is that the court resolved in Respondents’ favor factu al disputes such as whether there was lead present at the property at the time that Ms. O glesby lived there, whether Ms. Oglesby came into contact with lead at the property through peeling or chipping paint, and whether Ms. Oglesby was potentially exposed to lead at othe r locations and the condition of those properties. As our holding in Frankel, 480 Md. at 700-01, 281 A .3d at 703-04, demonstrates, where there is evidentiary support for the facts, a n expert is permitted to express an opinion based on disputed facts, and questions may be asked of an expert in the form of a hypothetical in which an expert may presume the tru th of certain facts as if they were not disputed. See also Fed. R. Evid. 702, advisory com mittee’s notes to 2000 amendment (“When facts are in dispute, experts sometimes reac h different conclusions based on competing versions of the facts. The emphasis in t he amendment on ‘sufficient facts or

data’ is not intended to authorize a trial court to exclude an expert’s testimony on the ground that the court believes one version of the f acts and not the other.”). In short, a trial court is not permitted to resolve disputes of mater ial fact in determining whether a sufficient factual basis exists to support an exper t’s opinion. Doing so is a clear abuse of

discretion.

B. Sufficient Factual Basis Although the facts were greatly disputed, Ms. Ogles by produced more than sufficient evidence that lead was present in the bu ilding at 2000 East North Avenue, that- 35 -

she was exposed to lead-based paint at the property , and that the property was a source of her elevated BLLs and alleged injuries (other than her IQ loss) to provide a sufficient factual basis for Dr. Caplan’s opinions. Before ad dressing the factual basis for Dr. Caplan’s testimony, it is helpful to discuss princi ples of causation in lead-based paint cases. Causation in lead-based paint cases may be proven b y showing that the defendant’s negligence was a “substantial factor” in causing th e plaintiff’s injury. Ross v. Hous. Auth. of Balt. City, 430 Md. 648, 667, 63 A.3d 1, 12 (201 3) (cleaned up). We have held that a customary theory of specific causation 25 in a lead-based paint case can be conceived of as a series of links: “(1) the link between the defend ant’s property and the plaintiff’s exposure to lead; (2) the link between specific exposure to lead and the elevated [BLLs;] and (3) the link between those [BLLs] and the injuries allegedl y suffered by the plaintiff.” Ross, 430 Md. at 668, 63 A.3d at 12. The first, second, and third links have sometimes been referred to as source, source causation, and medical causati on, respectively. See, e.g., Rogers v. Home Equity USA, Inc., 453 Md. 251, 265, 160 A.3d 1 207, 1215 (2017). With respect to the first link, the source of a plaintiff’s exposur e to lead, it may be established either with or without expert testimony. See Ross, 430 Md. at 669, 63 A.3d at 13 (“[T]he link between a defendant’s property and a plaintiff’s childhood exposure to lead paint and dust may be established through circumstantial evidence, even i f expert testimony is not available.”). Indeed, even the second or third link may potential ly be established without expert

25 “General causation addresses whether a particular s ubstance can cause the kind of injury suffered by the plaintiff[,]” and “[s]pecifi c causation addresses whether the substance actually caused the plaintiff’s injury.” Sugarman, 460 Md. at 415-16, 190 A.3d at 355 (citations omitted).- 36 -

testimony. See, e.g., id. at 668, 63 A.3d at 13 (“ Expert opinion testimony could be helpful in establishing any of the links and might sometime s be essential in proving the second and third links.” (Footnote omitted)). To avoid summary judgment in a lead-based paint cas e, “a plaintiff must demonstrate only a reasonable probability as to eac h of these links”—a plaintiff is not required to irrefutably establish them. Rogers, 45 3 Md. at 265, 160 A.3d at 1215 (citation omitted). Case law has recognized two ways in whic h a plaintiff in a lead-based paint case can establish the subject property as a reasonably probable source of the plaintiff’s lead exposure and resulting elevated BLLs. In Dow v. L & R Props., Inc., 144 Md. App. 67, 76-77, 796 A.2d 139, 144-45 (2002), the Appellate C ourt of Maryland held that a plaintiff can defeat a motion for summary judgment by present ing evidence that the subject property is the only possible source of the plaintiff’s lead exposure. With the second method, if there are allegedly multiple possible sources of le ad exposure, a plaintiff can produce “enough evidence to establish that it is reasonably probable that the subject property contributed to [the plaintiff’s] lead poisoning.” Rogers, 453 Md. at 266, 160 A.3d at 1216. In such cases, a plaintiff can “rule in” the subjec t property as a reasonably probable source through either direct or circumstantial evidence. Id. at 266, 160 A.3d at 1216 (citation omitted).

Source and Source Causation In this case, Ms. Oglesby sought to introduce Dr. C aplan’s expert testimony with respect to all three of the causation links. Even though, as Ms. Oglesby argues on brief, there was other evidence with respect to the proper ty being a source of her exposure to- 37 -

lead, Ms. Oglesby sought to use Dr. Caplan’s testim ony to assist in establishing the first causal link, the link between the property and her exposure to lead, i.e ., Ms. Oglesby sought to use Dr. Caplan’s testimony to assist in “ruling in” 2000 East North Avenue. In his report, Dr. Caplan concluded that Ms. Oglesby’s “likely exp osure to lead at 2000 E. North Ave is a significant contributing factor to her lead intox ication and, therefore, to her” impairments. And, at deposition, Dr. Caplan testified that Ms. O glesby’s second BLL of 5.5 μg/dL was related to her residency at the building. In reach ing these conclusions, Dr. Caplan did not offer the opinion that 2000 East North Avenue was t he sole source of Ms. Oglesby’s exposure to lead paint; rather, the substance of hi s report and testimony demonstrates that Dr. Caplan’s opinion was, as stated, that Ms. Ogles by’s likely exposure to lead at the building was a significant contributing factor to h er injuries. In other words, Ms. Oglesby endeavored to use Dr. Caplan’s expert testimony and other evidence to establish a reasonable probability that exposure to lead-based paint at 2000 East North Avenue contributed to her alleged injuries—to rule in the property as a source of her exposure. In reaching the conclusion that Ms. Oglesby’s likel y exposure to lead at 2000 East North Avenue was a significant contributing factor to her injuries, Dr. Caplan’s report and deposition testimony show that he relied on data, i ncluding: (1) independent test results showing the presence of lead in the building both b efore and after Ms. Oglesby’s residency; (2) reports of Crowninshield and others indicating that the building was in poor or bad condition during the time of Ms. Oglesby’s residenc y; (3) the testimony of Ms. Powell and others regarding chipping and peeling paint in the apartment and the building; (4) Ms. Oglesby’s BLLs; and (5) Dr. Hawkins-Heitt’s and Mr. Lieberman’s reports. Dr. Caplan- 38 -

explained in his report: [Ms. Oglesby] lived at 2000 E. North Ave from Decem ber 1998 through late 2001 or early 2002. This is a building built befor e 1950 with multiple inspections indicating the presence of lead based p aint. The Baltimore City Health Department issued an Emergency Lead Paint Vi olation Notice on October 5, 1989. Arc Environmental performed an in spection on April 13, 2011 and found multiple areas containing lead. Arc Environmental also performed inspections of multiple properties on the 2000 block of E. North Ave and found lead based paint in multiple areas of the seven properties. Green Street Environmental analyzed 2000 E. North A ve from April 17-18, 2012 and again from June 30, 2014 to July 3, 2014. Multiple areas containing lead based paint were identified during both inspec tions. Furthermore, multiple other children who lived at 2000 E. North Ave from the late 1980’s to the early 2000’s suffered from lead intoxication . For [Ms. Oglesby] the lead paint was accessible during her tenancy. Her mother described the apartment as being in poor condition with peeling a nd chipping paint throughout the hallways and stairwells as well as f rom the doors. In her apartment the paint began to peel about six months after she moved in. Some repainting was performed in the hallways, stairways , and on one window inside her apartment. However, the chipping and pe eling restarted after the repainting. Indeed the annual inspection dated 10/ 7/01 indicated multiple rooms needing rehabilitation. [Ms. Oglesby] moved in late 2001 or 2002 to 2800 Lafayette for a few weeks before moving again to 1713 Lemmon Street, both of which had no peeling paint. There were no significant visitations to other properties for [Ms. Oglesby] during this time

. In his report, Dr. Caplan set forth the dates and r esults of Ms. Oglesby’s BLL tests and explained that her BLLs were: 4/19/99 2 mcg/dl venous 3/27/02 5.5 mcg/dl venous 8/20/04 4 mcg/dl venous In forming his opinion about Ms. Oglesby’s exposure to lead at the property, Dr. Caplan relied on sources of information, not connec ted to Ms. Oglesby or Ms. Powell, showing the presence of lead in the building both b efore and after Ms. Oglesby’s residency. Specifically, Dr. Caplan reported that in October 1 989 (nearly a decade before Ms. Oglesby- 39 -

lived in the building), the Baltimore City Health D epartment issued an emergency violation notice for the building. According to Baltimore Ci ty Health Department records which were among the items reviewed by Dr. Caplan, the He alth Department issued the violation notice for Apartment G-2 after determining that a c hild who visited the apartment had an abnormal BLL and an inspection of the apartment sho wed that it contained lead-based paint. Similarly, Dr. Caplan reported that in April 2011 ( nine years after Ms. Oglesby moved from the building), Arc Environmental conduct ed inspections of multiple properties

in the 2000 block of East North Avenue and found le ad-based paint in seven of the properties. According to the Arc Environmental repo rt, which was one of the items reviewed by Dr. Caplan, in April 2011, a lead-based paint inspection of Apartment 203 and other areas of the building resulted in findings th at lead-based paint above the Maryland standard was detected on window jambs in the living room and in two bedrooms in Apartment 203 and in certain common areas of the bu ilding, including on the first-tosecond floor rear stairs baluster and newel post an d on the second-floor hallway window jamb. Dr. Caplan noted in his report that, in 2012 and 20 14, Green Street Environmental analyzed the property and identified multiple areas containing lead-based paint. According to Green Street Environmental’s April 2012 report, the company tested components of the building for the presence of lead-based paint and f ound that 84 areas throughout the building contained lead-based paint. Green Street Environmental’s report showed that lead was found on every floor of the building in numerou s locations, including in rooms that- 40 -

would previously have been apartments. Green Stree t Environmental’s report and secondfloor floorplan demonstrated that, of the rooms on the second floor that did not test positive for lead-based paint—namely, rooms 1 (a stairway), 2 (a hallway), 8 (a large area marked partly destroyed and inaccessible), and rooms 10 an d 12 (potentially apartments in the past)—there were only three rooms, 8, 10, and 12, t hat could potentially have once been apartments; rooms 1 and 2 were a stairway and a hal lway. Together, these three independent sources of inform ation demonstrated that leadbased paint was present in the building before and after Ms. Oglesby lived there and supported Dr. Caplan’s conclusion that Ms. Oglesby was likely exposed to lead-based paint at the property during her tenancy in the building. The testing revealing the presence of lead in the building before and after Ms. Oglesby’s residency is particularly persuasive concerning the adequacy of the factual basis for Dr . Caplan’s opinion as to source causation. There is a lack of any evidence that th e building underwent a lead-based paint abatement or gut rehabilitation after 1989, at some point before Ms. Oglesby’s residence in 1998. As the Appellate Court explained in Taylo r v. Fishkind, 207 Md. App. 121, 144, 148, 51 A.3d 743, 757, 759 (2012), cert. denied, 43 1 Md. 221, 64 A.3d 497 (2013), when reviewing a trial court’s grant of summary judgment , “[i]f the property contained leadbased paint when it was originally constructed, the n lack of evidence of a gut rehabilitation prior to [the plaintiff] living there would support the conclusion that the property still contained lead-based paint when [the plaintiff] liv ed there.” See also Rogers, 453 Md. at 272-73, 160 A.3d at 1219-20 (same). In addition, o ur case law confirms that the federal government no longer permitted lead-based paint to be used after 1978, negating the- 41 -

possibility that the property may have been entirel y abated of lead-based paint at some point after the 1989 Health Department inspection r esults and repainted with lead-based paint after Ms. Oglesby’s departure in January or F ebruary 2002, thereby accounting for the 2011 and 2012 test results showing the presence of lead in the building. See Levitas, 454 Md. at 248, 164 A.3d at 237. In addition to independent tests showing the presen ce of lead in the building, Dr. Caplan was aware, from sources other than Ms. Powel l, that she and Ms. Oglesby were required to move out of the building because it was in poor condition. Dr. Caplan had reviewed the October 7, 2001 annual inspection repo rt from Crowninshield for Apartment 202 and, in his report, specifically noted that the annual inspection report indicated that multiple rooms in the apartment needed rehabilitati on. At deposition, Dr. Caplan testified that the October 2001 inspection report “said that rehab was needed in multiple rooms: living room, dining room, bedrooms, bathroom[], kit chen and they were closing . . . that apartment building. . . . [T]he whole apartment bui lding was closed at the beginning of 2002 because of its poor condition.” The October 7, 2001 inspection report provided independent support for Dr. Caplan’s conclusion tha t lead was accessible and Ms. Oglesby was likely exposed to lead at the building. Prior to issuing his report, Dr. Caplan also review ed Ms. Powell’s deposition testimony regarding chipping and peeling paint in t he apartment and the rest of the building. At deposition, Ms. Powell described the building as having peeling and chipping paint everywhere in the building, throughout the ha llways and stairwells and on the doors. Ms. Powell testified that, although approximately a year after she moved into the apartment- 42 -

management repainted the building’s common areas an d the apartment doors, the paint began peeling again. As to the apartment, Ms. Powe ll testified that the apartment was in poor condition when she first moved in, and that wi thin six or seven months, she noticed peeling paint throughout the apartment, on the wall s and windowsills, in the bathroom, and in a closet. Despite her request that management p aint locations inside the apartment, only one window inside the apartment was repainted. This testimony, although it may have been disputed, contributed to the factual basis for Dr. Caplan’s opinion that lead was accessible to Ms. Oglesby during her residency at t he building and that the building was a source of her lead exposure. Dr. Caplan also reviewed records documenting Ms. Og lesby’s BLL tests. At deposition, Dr. Caplan explained that the dates of Ms. Oglesby’s documented BLL tests, the circumstance that Ms. Oglesby’s BLL of 5.5 μg/d L was documented only two to three months after she moved away from 2000 East North Av enue, that she did not have significant visitations to other properties, and th at she moved to a place not reported to have peeling and chipping paint led to his conclusi on that it was very likely that 2000 East North Avenue was responsible for Ms. Oglesby’s BLL of 5.5 μg/dL. At bottom, although there may have been a dispute o f fact concerning whether Ms. Oglesby was exposed to lead at the property or at o ther locations, there was more than an adequate supply of data and information about the b uilding to support Dr. Caplan’s opinion that Ms. Oglesby was exposed to lead-based paint at 2000 East North Avenue. That Dr. Caplan did not rule out a property that Ms. Oglesby visited while living at 2000 East North Avenue or properties in which Ms. Oglesby lived bef ore or after moving from the building- 43 -

as sources of her exposure to lead would not render inadmissible his opinion regarding Ms. Oglesby’s exposure to lead 2000 East North Avenue b eing a significant contributing factor to her injuries. Cf. Levitas, 454 Md. at 250, 164 A.3d at 238 (“The substantial factor test does not require experts to exclude other propertie s as possible contributing sources. . . . It would be illogical for us to require an expert to n arrow the plaintiff’s lead exposure down to a single source when the substantial factor test , by its very definition, permits more than one cause of injury.” (Citation omitted)); id. at 250, 164 A.3d at 238 (It is “not the rule” “that an expert must exclude other properties befor e he can testify that the plaintiff was exposed to lead at the subject property.”). With r espect to source causation, “[w]e have only required that an expert be able to adequately explain how he determined that a property was a source of the plaintiff’s lead expos ure so that the trier of fact can evaluate his reasoning.” Id. at 251, 164 A.3d at 238-39 (ci tation omitted). In fact, we agree with Ms. Oglesby that this case i s similar to Levitas, id. at 250-51, 164 A.3d at 238-39, in which we held that a trial c ourt abused its discretion in excluding an expert’s opinion that the defendant’s property w as likely a source of the plaintiff’s exposure to lead-based paint. In Levitas, id. at 2 48-49, 164 A.3d at 237, the expert took into account the circumstances that the plaintiff’s BLLs “were first found to be elevated while he was living at [the building], when he had not yet lived anywhere else[,]” and that he “regularly stayed at [the building] during the d ay while his mother was at work, both when he lived there and when he lived at” a subsequ ent residence. (Emphasis omitted). The expert also considered that: an Arc Environment al report found that 31 interior and 5 exterior locations tested positive for lead; lead-b ased paint was federally banned in 1978,- 44 -

making it unlikely that the building had been paint ed with lead-based paint since the plaintiff lived in the building in the 1990s; Maryl and Department of Housing and Community Development records described the poor co ndition of the property; a Maryland Department of the Environment certification indicat ed that the building was not lead free; and the plaintiff’s family members testified that t he building was in a deteriorated condition while the plaintiff lived there and the plaintiff t ouched peeling paint at the property. See id. at 248-49, 164 A.3d at 237. In Levitas, id. at 250-51, 164 A.3d at 238-39, we concluded

that the trial court abused its discretion in exclu ding the expert’s testimony on causation because, in the trial court’s view, the expert had little information as to other sources of lead exposure. We explained that, in so ruling, th e trial court mistakenly “relied on a purported rule of law that an expert must exclude o ther properties before he can testify that the plaintiff was exposed to lead at the subject pr operty.” Id. at 250, 164 A.3d at 238. 26 Ms. Oglesby also sought to use Dr. Caplan’s testimo ny to assist with establishing

26 By contrast, in another case, Ross, 430 Md. at 663, 63 A.3d at 10, we held that a trial court did not abuse its discretion in determi ning that an expert lacked an adequate factual basis to opine that the defendant’s buildin g was “the source” of the plaintiff’s exposure to lead-based paint. We concluded that th e expert “did not explain adequately how she reached the conclusion that the [subject pr operty] was ‘the source’ of the lead exposure that resulted in” the plaintiff’s elevated BLLs. Id. at 664, 63 A.3d at 10. We explained that, “[g]iven the uncontroverted evidenc e that there were various other sources of lead exposure in [the plaintiff]’s environment, including her prior residence, and that she came to the [subject property] with already ele vated [BLLs], there were likely multiple causes of her elevated [BLLs].” Id. at 664, 63 A.3 d at 10. We determined that “[t]he real question for the fact-finder [wa]s how much exposur e to lead at the [subject property] contributed to [the plaintiff’s BLLs] over the pert inent time period[.]” Id. at 664, 63 A.3d at 10 (emphasis omitted). We concluded that the tr ial court did not abuse its discretion in determining that the expert’s opinion would not ass ist the fact-finder in answering that question. See id. at 664-65, 63 A.3d at 10.- 45 -

the second link, i.e ., the link between her exposure to lead at the pro perty and her BLLs. The information that Dr. Caplan relied on concernin g the presence of lead-based paint in the building before and after Ms. Oglesby’s residen cy, and the deteriorated condition of the building and the apartment at the time that Ms. Oglesby lived there, giving Ms. Oglesby access to lead-based paint during the time she live d in the building, was sufficient to support the opinion that Ms. Oglesby was likely exp osed to lead at 2000 East North Avenue. That information, coupled with Ms. Oglesby ’s documented BLLs—specifically, that she had a BLL of 2 μg/dL in April 1999, only a few months after she moved into the building, and that she had a BLL of 5.5 μg/dL in Ma rch 2002, just two to three months after she moved out of the building—as well as info rmation that Ms. Oglesby did not have significant visitations to other properties during this time and that the property Ms. Oglesby moved into did not have chipping and peeling paint, although disputed by the parties, provided a sufficient factual basis for Dr. Caplan to render an opinion concerning the second causal link, the link between specific expos ure to lead at the property and Ms. Oglesby’s BLLs. Clearly, issues concerning the frequency of Ms. Ogl esby’s visits to the Lafyette property on weekends and whether the Lafayette prop erty and other properties that Ms. Oglesby lived in before or after residing at 2000 E ast North Avenue contained lead-based paint involve issues of disputed facts. The credib ility of Ms. Powell’s testimony regarding the frequency and duration of Ms. Oglesby’s weekend visits and the condition of other properties is a matter for the trier of fact to det ermine, not the circuit court in ruling on the motion to preclude. See Frankel, 480 Md. at 700-01 , 281 A.3d at 703. In other words,- 46 -

subject to the premise that the jury would be made aware of the existence of any genuinely disputed facts, the information that Dr. Caplan rel ied on from Ms. Powell’s testimony provided a sufficient factual basis for his opinion linking Ms. Oglesby’s specific exposure to lead at the property to her documented BLL of 5. 5 μg/dL in March 2002. See id. at 700- 01, 281 A.3d at 703.

Medical Causation Setting aside the issue of IQ loss, Dr. Caplan also had a sufficient factual basis to offer an opinion as to the third causal link—the li nk between Ms. Oglesby’s BLLs and her other alleged injuries—when concluding that Ms. Ogl esby’s likely exposure to lead at 2000 East North Avenue was a significant contributing fa ctor to her cognitive impairments. Dr. Caplan pointed out in his report that, according to the United States Environmental Protection Agency, the American Academy of Pediatri cs, the Maryland Department of the Environment, and the World Health Organization, lea d is a causal or likely causal factor for the type of impairments Ms. Oglesby suffered. In this case, there is no challenge to the principle that the types of impairments and limitat ions documented by Dr. Hawkins-Heitt and Mr. Lieberman, which are described in Dr. Capla n’s report, can be caused by exposure

to lead. In the motion to preclude, Respondents took issue w ith the factual basis for Dr. Caplan’s opinions as to causation of Ms. Oglesby’s alleged injuries, alleging that Dr. Caplan lacked a sufficient factual basis for his te stimony because he relied on a “selective review of the evidence to support his opinion that the Property was the source of [Ms. Oglesby]’s childhood lead exposure, and that childh ood lead exposure caused her injuries.”- 47 -

Similarly, before this Court, Respondents advance t he claim that “Dr. Caplan lacked a sufficient factual basis to opine that [Ms.] Oglesb y suffered injuries as a result of lead exposure at the Property[,]” due to the “limited ev idence that Dr. Caplan received from [Ms. Oglesby’s] counsel[.]” (Bolding omitted). In other words, as an extension of the argument that Dr. Caplan lacked an adequate supply of data for his opinion as to source causation, Respondents allege that Dr. Caplan also lacked an adequate supply of data for the opinion that Ms. Oglesby’s exposure to lead at 2000 East North Avenue was a significant contributing factor to her alleged inju ries. We have already assessed this contention and dispensed with it; the record reflec ts that Dr. Caplan had more than an adequate supply of data for the opinion that Ms. Og lesby was exposed to lead-based paint at the property. That an expert have both an adequate supply of data and use reliable methodology are well-recognized aspects of having a sufficient factual basis for an opinion under Maryland Rule 5-702(3). See Sugarman, 460 Md. at 4 15, 190 A.3d at 354. In the “Introduction” section of the motion to preclude, R espondents asserted that “Dr. Caplan’s medical opinions, and any opinion testimony based o n them, should be precluded under Maryland Rule 5-702” and the Frye-Reed standard “be cause they lack a sufficient factual basis and are not the product of a reliable methodo logy.” 27 On brief in this Court,

27 In a section of the motion titled “Legal Standard,” along with other authority, Respondents cited general case law indicating that both an adequate supply of data and reliable methodology are necessary for the admissio n of expert opinion and that opinions based on conjecture and speculation are not admissi ble. And, Respondents quoted the well-established principle that “an expert opinion must provide a sound reasoning process- 48 -

Respondents state that the circuit court properly e xercised its discretion to find that “Dr. Caplan did not use a reliable methodology to form h is opinions regarding Oglesby’s alleged injuries,” and state that the circuit court exclude d Dr. Caplan’s opinions as “inherently

unreliable.” To be sure, the record reflects that, at one point during the motions hearing while ruling, the circuit court stated that “there are is sues, if you will, with the facts and the information that was gathered, and how it was gathe red, and who he spoke to, and who he didn’t speak to[,]” and that “the basis of the Cour t’s ruling is not only when you combine

those issues with the issue of the use of the metho dology, the Court believes that together that makes his testimony and opinion inherently unr eliable.” This was part of the circuit court’s response to Ms. Oglesby’s counsel’s request for clarification as to whether its ruling that Dr. Caplan had used “incorrect” information ap plied to Ms. Oglesby’s case or Johnson’s. With these remarks, the circuit court r eferred mainly to what it described as issues with the facts, which the court believed in combination with “the issue of the use of the methodology” rendered Dr. Caplan’s testimony un reliable. The circuit court made no finding whatsoever with respect to “the issue of th e use of the methodology” 28 and provided no substantive basis for ruling that Dr. Caplan’s t estimony was inherently unreliable. This

for its conclusion from the factual data” and the e xplanation for the opinion must not be “conclusory.” (Citation omitted).

28 Earlier, in its initial ruling, the circuit court’s only specific remarks concerning methodology referred to Dr. Caplan not using all av ailable BLLs in formulating his IQ loss opinion and that he offered no support for the “cal culations” he used.- 49 -

was far from a finding by the circuit court that Dr . Caplan’s opinion on medical causation as to Ms. Oglesby’s other alleged injuries was the product of unreliable methodology. On brief in this Court, Respondents assert that Dr. Caplan’s opinion that Ms. Oglesby suffered “neurocognitive injuries” was inad missible because he did not examine or administer tests to Ms. Oglesby, meet with her, or speak with her family, medical providers, or teachers. To the extent Respondents contend that Dr. Caplan’s opinions and testimony regarding Ms. Oglesby’s injuries are inad missible because he relied on Dr. Hawkins-Heitt’s report and did not personally exami ne Ms. Oglesby, this goes to the weight to be given to Dr. Caplan’s opinion, rather than its admissibility. In Levitas, id. at 251, 164 A.3d at 239, we rejected the defendant’s c ontention that an expert’s opinion lacked a sufficient factual basis because the exper t did not conduct his own examination of the plaintiff and instead relied on another expert’ s report, scientific research, school records, discovery materials, and deposition testim ony. Our case law demonstrates that an expert’s factual basis may arise from a number of s ources, including reports prepared by other doctors. See id. at 254, 164 A.3d at 240. When a challenge to the admissibility of expert tes timony is raised, “[t]he burden rests with the proponent of the expert testimony to demonstrate that the[] requirements [of Maryland Rule 5-702] have been met.” Rochkind, 454 Md. at 286, 164 A.3d at 259 (citation omitted). In this case, we are satisfied that, with respect to the data and methodology used by Dr. Caplan for his opinion as t o Ms. Oglesby’s alleged injuries (other than IQ loss), Ms. Oglesby has done so. The proces s that Dr. Caplan used in reaching his opinion is similar to that of medical experts who h ave been permitted in other cases to- 50 -

render an opinion that a plaintiff’s exposure to le ad was a significant contributing factor to impairments like those attributed to Ms. Oglesby. See, e.g., Levitas, 454 Md. at 251-55, 164 A.3d at 239-41. Dr. Caplan evaluated informati on such as Ms. Oglesby’s time of residency at the property, independent reports conc erning the presence of lead and the condition of property, Ms. Oglesby’s documented BLL s, and medical and vocational evaluations describing Ms. Oglesby’s impairments, a nd, based on his knowledge and experience, provided a reasonable explanation of ho w the factual data led to his conclusions. See id. at 251-55, 164 A.3d at 239-41 . Under the particular circumstances of this case, given the large quantity of data that he had available and reviewed and the nature of the challenge to the admissibility of his testim ony, a remand for further proceedings as to Dr. Caplan’s opinion that Ms. Oglesby’s exposure to lead at the property was a substantial contributing factor to her injuries (ot her than IQ loss) is not warranted.

II. Dr. Caplan’s Opinion with Respect to IQ Loss A. The Canfield and Lanphear Studies Respondents contend that Dr. Caplan’s testimony co ncerning Ms. Oglesby’s IQ loss is inadmissible because, in their view, Dr. Caplan’ s explanation of his use of the Canfield and Lanphear studies does not support a finding tha t his methodology was reliable. On brief, Respondents state that “the issue is not the fact that Dr. Caplan relied on the Lanphear and Canfield studies; the issue is how Dr. Caplan u sed those studies to calculate [Ms.] Oglesby’s alleged IQ loss.” (Cleaned up). Based o n their review of the studies, Respondents raise the following complaints: (1) the studies contain language indicating that causal inferences may not be made, and Dr. Cap lan used linear calculations; (2) Dr.- 51 -

Caplan used a peak BLL in a manner that is contradi cted by information in the studies; and (3) he miscalculated Ms. Oglesby’s average BLL. To frame our discussion, we begin with some relevan t information about the studies. The Canfield study “measured blood lead concentrati ons in 172 children at 6, 12, 18, 24, 36, 48, and 60 months of age”— i.e. , 1⁄2 a year old, 1 year old, and 11⁄2, 2, 3, 4, and 5 years old. Richard L. Canfield, Charles R. Henderson, Jr ., Deborah A. Cory-Slechta, Christopher Cox, Todd A. Jusko, and Bruce P. Lanphear, Intellec tual Impairment in Children with Blood Lead Concentrations below 10 μg per Deciliter , 348 New Eng. J. of Med. 1517 (Apr. 17, 2003), available at https://www.ncbi.nlm.nih.go v/pmc/articles/PMC4046839/ [https:// perma.cc/JV55-68C3]. The study explained that “[t] he relation between IQ and blood lead

concentration was estimated with the use of linear and nonlinear mixed models, with adjustments for maternal IQ, quality of the home en vironment, and other potential confounders[,]” and that results demonstrated that “blood lead concentration was inversely and significantly associated with IQ.” Id. The st udy stated that, “[w]hen estimated in a nonlinear model with the full sample, IQ declined b y 7.4 points as lifetime average blood lead concentrations increased from 1 to 10 μg[/dL]. ” Id. 29 The Canfield study explained that “[p]revious research is consistent with the in terpretation that the effects of lead on IQ are proportionally greater at lower lead concentrat ions.” 348 New Eng. J. of Med. at 1522. As to IQ at blood-lead concentrations below 10 μg/d L, the Canfield study related

29 The Canfield study also stated that, using the line ar model, “the estimated IQ loss was 4.6 points for each increase in the blood lead concentration of 10 μg per deciliter,” and that “for children whose lead concentrations remain ed below 10 μg per deciliter, the estimated loss in IQ was considerably greater.” 34 8 New Eng. J. of Med. at 1521.- 52 -

that “linear models for each lead variable were est imated for the subgroup of children whose peak lead concentration was below 10 μg per d eciliter” and that, “[w]ithout exception, the estimates were larger in this subgro up.” Id. at 1521. The Canfield study stated that, using nonlinear mixed models, the “[s] emiparametric analysis indicated a decline in IQ of 7.4 points for a lifetime average blood lead concentration of up to 10 μg per deciliter[.]” Id. Similarly, the Lanphear study starts by noting that “[t]here is emerging evidence

that lead-associated intellectual deficits occur at [BLLs less than] 10 μg/dL” and cites eight studies for this point. Bruce P. Lanphear, Richard Hornung, Jane Khoury, Kimberly Yolton, Peter Baghurst, David C. Bellinger, Richard L. Canfield, Kim N. Dietrich, Robert Bornschein, Tom Greene, Stephen J. Rothenberg, Herb ert L. Needleman, Lourdes Schnaas, Gail Wasserman, Joseph Graziano, and Russe ll Roberts, Low-Level Environmental Lead Exposure and Children’s Intellec tual Function: An International Pooled Analysis, 113 Env’t Health Persps. 894 (July 2005), available at https://www.ncbi. nlm.nih.gov/pmc/articles/PMC1257652/ [https://perma .cc/8LT6-NZZQ]. The study explained that it contacted investigators of the st udies and obtained “data sets and collaboration” from seven of the eight. Id. The s tudy described itself as a pooled analysis that estimated “the quantitative relationship betwe en children’s performance on IQ tests

and selected measures of blood lead concentration a mong children followed prospectively, from infancy through 5–10 years of age in seven pro spective cohort studies.” Id. “To enhance comparability across studies, [the study] u sed the following blood sampling- 53 -

intervals (based on children’s age): 6, 12 (or 15), 36, 48, and 60 months”— i.e. , 1⁄2 a year old, 1 year old (or 11⁄4 years old), and 3, 4, and 5 years old. Id. at 895. As to results, the Lanphear study stated that, “[f] or the entire pooled data set,” there was an “observed decline of 6.2 IQ points [] for an increase in [BLLs] from < 1 to 10 μg/dL[.]” Id. at 898. The Lanphear study stated t hat this “was comparable with the 7.4 IQ decrement for an increase in lifetime mean [BLLs] f rom < 1 to 10 μg/dL observed in the” Canfield study. Id. The Lanphear study stated tha t, consistent with other studies, “the lead-associated IQ deficits observed in this pooled analysis were significantly greater at lower blood lead concentrations.” Id. The Lanphea r study also determined that, by using the larger sample size of the pooled analysis, it w as able “to show that the lead-associated intellectual decrement was significantly greater fo r children with a maximal blood lead of < 7.5 μg/dL than for those who had a maximal blood lead of ≥ 7.5 μg/dL.” Id.

B. Relevant Case Law This Court has held that “a properly qualified expe rt witness can rely on the Lanphear Study methodology, as well as other accept ed scientific research, as a factual basis for an opinion that a plaintiff’s elevated BL Ls caused the loss of a specific number of IQ points.” Sugarman, 460 Md. at 434, 190 A.3d at 366 (citing Levitas, 454 Md. at 254- 55, 164 A.3d at 241; Roy v. Dackman, 445 Md. 23, 51 n.16, 124 A.3d 169, 186 n.16 (2015); Rochkind v. Stevenson, 229 Md. App. 422, 469-70, 14 5 A.3d 570, 598 (2016), rev’d, 454 Md. 277, 164 A.3d 254 (2017)). In Roy, 445 Md. at 33, 124 A.3d at 175, we consider ed whether an expert witness could render an opinion that lead-based paint at a property caused the plaintiff’s medical- 54 -

injuries, which included “a loss of IQ points, impa ired attention, problems with memory, and problems with coordination.” (Cleaned up). Th e expert relied on the pooled Lanphear study to form an opinion about the plaintiff’s IQ l oss due to lead exposure. See id. at 51 & n.16, 124 A.3d at 186 & n.16. The defendants took issue with the expert’s use of the study, contending that there “have been peer-reviewed stud ies published in highly respected journals not only directly contradicting the studie s on which [the expert] relie[d], but also calling into question the application of the studie s to any one individual without real-life evidence of actual IQ point loss.” Id. at 51 n.16, 124 A.3d at 186 n.16. We concluded that the expert’s reliance on the Lanp hear study did “not invalidate the entire basis of his opinion, even if the Lanphe ar study [was] contrary to the results of other studies as alleged by [the defendants]. Such is the grist for cross-examination and dueling experts and for resolution by the relative weight assigned by the fact-finder.” Id. at 51 n.16, 124 A.3d at 186 n.16. We determined th at the record demonstrated that the expert possessed “a sufficient background from whic h to provide an opinion as to the injuries claimed to have been suffered by [the plai ntiff] as the result of alleged exposure to lead.” Id. at 52, 124 A.3d at 186. But, whether a jury would find the expert’s testimony persuasive would “depend, in large measure, on the effectiveness of [the defendants’] cross-examination and a comparison/weighing by the jury against [the defendants’] competing witness(es)’ testimony.” Id. at 52, 124 A.3d at 186. In Rochkind, 229 Md. App. at 465, 145 A.3d at 596, where an expert’s opinion quantified the plaintiff’s IQ loss, the Appellate C ourt addressed whether the expert’s calculations were reliable under Frye-Reed and whet her the expert had an adequate factual- 55 -

basis under Maryland Rule 5-702(3). 30 The Appellate Court concluded that the trial cour t did not abuse its discretion in finding the expert’ s methodology reliable where the expert extrapolated from the Lanphear study to estimate a specific IQ loss in the plaintiff. See Rochkind, 229 Md. App. at 469, 145 A.3d at 598. In Rochkind, id. at 466-67, 145 A.3d at 596-97, relying on the Lanphear study, the expert t estified that the plaintiff lost between 5 and 6 IQ points as a result of exposure to lead. T he expert testified that, based on the Lanphear study, she used the plaintiff’s peak BLL o f 14 μg/dL and “calculated an IQ loss of 3.9 points based upon a level of between zero an d ten, 0-10 μg/dL[,] and an additional loss of 1.9 points for the level between 10 and 20 μg/dL, for a total of 5.8.” Id. at 466-67, 145 A.3d at 597. The expert explained that her opi nion would not have changed if she had used the plaintiff’s average BLL of 11.5 μg/dL. Se e id. at 466-67, 145 A.3d at 597. The Appellate Court determined that, because, as th e defendant acknowledged, “there is a scientific consensus that lead poisonin g causes IQ loss, the only issue [was] whether the trial court abused its discretion by al lowing [the expert] to opine that [the plaintiff] sustained a specific IQ loss of between five and six points.” Id. at 469, 145 A.3d at 598. The Appellate Court concluded that the tri al court did not abuse its discretion in accepting as “sound” the expert’s methodology of “e xtrapolating from epidemiological studies quantifying IQ loss resulting from lead exp osure in the general population to

30 This Court reversed the Appellate Court’s judgment on a different ground, concluding that the trial court abused its discreti on in permitting the expert to testify that lead exposure can cause attention-deficit/hyperacti vity disorder (“ADHD”) generally and that lead caused the plaintiff’s ADHD specifically. See Rochkind, 454 Md. at 295-96, 164 A.3d at 265. No issue concerning the expert’s opin ion as to IQ loss was before this Court. See id. at 284-85, 164 A.3d at 258.- 56 -

estimate the range of IQ loss in an individual.” I d. at 469, 145 A.3d at 598. The Appellate Court stated that the expert “fully explained the b asis for her calculation on the IQ loss” during “vigorous cross-examination[.]” Id. at 470, 145 A.3d at 598. Accordingly, the Appellate Court concluded that the expert’s opinion as to IQ loss was supported by an adequate factual basis. See Rochkind, 229 Md. App. at 470, 145 A.3d at 599. In Levitas, 454 Md. at 254-55, 164 A.3d at 241, rel ying on Roy, we concluded that an expert could use the Lanphear study to calculate the plaintiff’s individual IQ loss. In Levitas, 454 Md. at 240, 164 A.3d at 232, at deposi tion, the plaintiff’s expert witness testified that, as a result of the plaintiff’s expo sure to lead, the plaintiff lost 7.4 to 9.4 IQ points. In calculating the plaintiff’s IQ loss, th e expert relied on the Lanphear study, and averaged the plaintiff’s BLLs and “determined his l oss in IQ points based on the study’s results.” Id. at 240-41, 164 A.3d at 232. The tri al court excluded the expert’s opinion, ruling that the expert lacked a sufficient factual basis under Maryland Rule 5-702(3). See id. at 241, 164 A.3d at 233. Before this Court, the defendant contended that the expert could not calculate the plaintiff’s “IQ loss using the Lanphear study becau se it is population-based, and therefore cannot be used to calculate an individual’s IQ loss .” Id. at 254, 164 A.3d at 240. Relying on Roy, 445 Md. at 51-52 & n.16, 124 A.3d at 185-86 & n.16, we rejected the defendant’s contention, stating that, despite other reputable s tudies contradicting the Lanphear study’s results and cautioning against using it to calculat e individual IQ loss, relying on the Lanphear study did not invalidate the basis of an e xpert’s opinion. See Levitas, 454 Md.- 57 -

at 254-55, 164 A.3d at 241. 31 In Sugarman, 460 Md. at 432-34, 190 A.3d at 365-66, after reviewing Roy, Rochkind, and Levitas, we stated unequivocally: “ Levitas and Roy demonstrate that a properly qualified expert witness can rely on the L anphear Study methodology, as well as other accepted scientific research, as a factual ba sis for an opinion that a plaintiff’s elevated BLLs caused the loss of a specific number of IQ poi nts.” (Citations omitted). We explained that “[l]egitimate scientific disputes go not to the admissibility of testimony, but to the weight of the evidence.” Sugarman, 460 Md. at 434, 190 A.3d at 366. In Sugarman, id. at 403, 190 A.3d at 348, the plaintiff offered Robert Kraft, Ph.D., as an expert in the fields of psychology and neuropsychology, who condu cted a neuropsychological examination of the plaintiff consisting of an inter view and several tests to assess aspects of intelligence. Dr. Kraft testified that the plainti ff had a full-scale IQ of 94, which placed him in the average range, but noted that test score s “indicated that [the plaintiff] had some form of brain impairment.” Id. at 403, 190 A.3d at 348. The plaintiff offered Jacalyn Blackwell-White, M.D. , as an expert in the fields of pediatrics and childhood lead poisoning. See id. a t 405, 190 A.3d at 349. Dr. Blackwell31 In Levitas, 454 Md. at 240 & n.6, 164 A.3d at 232 & n.6, following our first reference to the Lanphear study, we provided the ci tation for the Canfield study instead— “Richard L. Canfield et al., Intellectual Impairment in Children with Blood Lead Concentrations Below 10 μg per Deciliter , 348 New Eng. J. of Med. 1517 (2003).” It is unclear whether we inadvertently cited the Canfield study or whether we meant to refer to the Canfield study instead of the Lanphear study. In any event, in Levitas, 454 Md. at 254- 55, 164 A.3d at 241, we summarized our discussion o f the Lanphear study in Roy, 445 Md. at 51-52 & n.16, 124 A.3d at 185-86 & n.16, a case in which we provided the citation to the Lanphear study.- 58 -

White reviewed the plaintiff’s medical records, Dr. Kraft’s report, and other records, and determined that the plaintiff incurred a brain impa irment due to lead toxicity, that the impairment included a loss of cognitive function, a nd that the plaintiff lost 4 IQ points due to lead toxicity. See id. at 405, 190 A.3d at 349. Among other studies, Dr. BlackwellWhite relied on the Lanphear study. See id. at 405 -06, 190 A.3d at 349. As to Dr. Blackwell-White’s opinion about the plain tiff’s IQ loss, we stated: Like the experts in Levitas and Roy , Dr. Blackwell-White relied on [the plaintiff]’s documented BLLs, the results of h is neuropsychological evaluation, and the Lanphear Study, to estimate a s pecific IQ point loss. She did not look only to his elevated BLLs, assume he h ad a cognitive defect, and then extrapolate a point loss based on the Lanphear methodology. Rather, Dr. Blackwell-White relied on evidence that [the pl aintiff]—individually— had already manifested cognitive defects. This gav e her enough reason to use her knowledge and expertise to extrapolate a lo ss of IQ points according to the methodology outlined in the Lanphear Study. [The defendant] presented contradictory experts and extensively cro ss-examined [the plaintiff]’s experts about their conclusions. That is what we contemplated in Levitas and Roy

. Sugarman, 460 Md. at 436-37, 190 A.3d at 367-68 (ci tations omitted). We concluded that “Dr. Blackwell-White’s testimony provided sufficien t evidence for the jury to draw the inference that, more likely than not, [the plaintif f]’s elevated BLLs caused a measurable loss of IQ points” and that the trial court properl y denied the defendant’s motions and allowed the question to go to the jury. Id. at 437 , 190 A.3d at 368.

The bottom line is that these cases demonstrate th at experts have been permitted to rely on the Lanphear study and extrapolate from its findings and render an opinion that an individual suffered a specified loss of IQ points a s a result of exposure to lead.- 59 - C. Application of Principles Above to This Case In this case, as with the experts in Sugarman, Lev itas, and Roy, Dr. Caplan relied on information about Ms. Oglesby, such as documente d BLLs, the results of the neuropsychological evaluation performed by Dr. Hawk ins-Heitt showing that Ms. Oglesby had a full-scale IQ score of 80 and cognitive impai rments, and the Lanphear study (as well as the Canfield study), to estimate specific IQ poi nt losses. Cf. Sugarman, 460 Md. at 436, 190 A.3d at 367. Although this Court and the Appel late Court have explicitly acknowledged that an expert may rely on and extrapo late from the Lanphear study to render an opinion as to an individual’s IQ loss, our case law has not yet assessed an expert’s use of the Canfield study in the same way. We note, th ough, that the Canfield study is one of the studies in the pooled analysis used in the Lanp hear study. See 113 Env’t Health Persps. at 894. And, the Lanphear study explained that its conclusion that there was a decline of 6.2 IQ points for an increase in BLLs from less tha n 1 to 10 μg/dL was comparable to the 7.4 IQ decrement observed in the Canfield study. S ee id. at 898. At the outset of our discussion, we observe that R espondents raised in the motion to preclude, and on brief in this Court, arguments tha t appear to go to the reliability of Dr. Caplan’s methodology as well as arguments that are better suited for cross-examination, rather than the exclusion of Dr. Caplan’s testimony . As an example of the latter, at least with respect to the Lanphear study, Respondents ide ntify a statement in the study that “[t]he observational design of this study limits our abili ty to draw causal inferences” and argue that this language renders Dr. Caplan’s opinion con cerning Ms. Oglesby’s IQ loss inadmissible. That notwithstanding, as the case la w discussed above demonstrates, experts- 60 -

have been permitted to rely on the Lanphear study t o offer an opinion that exposure to lead caused IQ loss to a plaintiff. See Sugarman, 460 M d. at 436-37, 190 A.3d at 367-68; Roy, 445 Md. at 51 n.16, 124 A.3d at 186 n.16. There is no dispute the Lanphear study shows that exposure to lead-based paint can cause IQ loss . See, e.g., Sugarman, 460 Md. at 430,

190 A.3d at 363. Our case law contradicts the noti on that expert testimony as to specific causation in reliance on the Lanphear study is prec luded based solely on the language in the study that Respondents point out and suggests t hat the significance of the language the Respondents point out is a matter for cross-examina tion. See Sugarman, 460 Md. at 434, 190 A.3d at 366; Roy, 445 Md. at 51 n.16, 124 A.3d at 186 n.16. In another example of an argument better suited for cross-examination, Respondents assert that Dr. Caplan improperly multiplied using Ms. Oglesby’s peak BLL rather than her average lifetime BLL. Dr. Caplan’s testimony a t deposition confirms that he made calculations based on both Ms. Oglesby’s peak BLL a nd the average of her BLLs. Although the Lanphear study states that “average li fetime estimates of lead exposure were generally stronger predictors of lead-associated in tellectual deficits than” peak blood-lead concentration, 113 Env’t Health Persps. at 898, the Lanphear study did not state that an average BLL is the only predictor or that a peak BL L could not be used. And, in discussing IQ at blood-lead concentrations below 10 μg/dL, the Canfield study stated that “[l]ifetime average, peak, and concurrent blood lead concentrat ions, but not the average in infancy, were inversely and significantly associated with IQ [.]” 348 New Eng. J. of Med. at 1521. Neither study states that the average lifetime BLL is the only acceptable factor or indicator of lead exposure deficits. Moreover, case law demo nstrates that expert witnesses, relying- 61 -

on the Lanphear study, have been permitted to rende r an opinion as to IQ loss after extrapolating using either the average of a plainti ff’s BLLs, see Levitas, 454 Md. at 240- 41, 164 A.3d at 232, or a plaintiff’s peak BLL, see Rochkind, 229 Md. App. at 466-67, 145

A.3d at 597. Next, Respondents contend that Dr. Caplan incorrect ly calculated Ms. Oglesby’s average BLL by not using the computation method set forth in the Canfield study. The Canfield study states: [L]ifetime average blood lead concentration was est imated at 3 and 5 years of age by computing the area under the blood lead c urve (AUC) from 6 through 36 months of age and from 6 through 60 mont hs of age, respectively. Dividing the AUC by the corresponding age span yiel ds an average concentration expressed in micrograms per deciliter

. Respondents contend that Dr. Caplan did not perform the AUC calculation described in the Canfield study for Ms. Oglesby’s average BLL and in stead that he took just the mean of the three BLL test results as the average, which, a ccording to them, was wrong. Respondents do not make a corresponding allegation that the Lanphear study required the average BLL to be calculated in the same manner set forth in the Canfield study. 32 With respect to the Canfield study, this issue would be among the matters for the circuit court’s consideration on remand should Ms. Oglesby seek to introduce Dr. Caplan’s testimony concerning her IQ loss at trial and Respondents rai se the same objection. Respondents also argue that Dr. Caplan offered no s upport for using linear

32 The Lanphear study states that lifetime average blo od lead concentration “was defined as the mean of blood lead tests taken from 6 months through the concurrent blood lead test.”- 62 -

extrapolation, and observe that the Canfield study states that “the relation between children’s IQ score and their blood lead concentrat ion is nonlinear.” 348 New Eng. J. of Med. at 1521-22. In our view, neither the Lanphear study nor the Canfield study sets forth one correct way in which to apply its findings. To the extent that Respondents argue that language in the Lanphear study does not permit line ar extrapolation, as with the language concerning a potential limitation on causal inferen ces, this language has been in the study since its publication and, under Maryland case law, experts have been permitted not only to testify relying on the content of the Lanphear s tudy, but also to render opinions as to specific IQ point loss after calculations based on information in the study. That said, although our case law demonstrates it is permissible for an expert to rely on the Lanphear study to offer an opinion that expo sure to lead resulted in a specific loss of IQ points, the record in this case shows that ne ither Dr. Caplan’s report nor his deposition testimony fully explains the basis for his calculat ions under either study. To be sure, at deposition, Dr. Caplan testified that he made calcu lations using both Ms. Oglesby’s peak BLL of 5.5 μg/dL and an average BLL of 3.8 μg/dL. Implicit in the calculations is that Dr. Caplan determined that the Lanphear and Canfield st udies indicate that every 1 μg/dL

increase in a BLL leads to a loss of 0.62 or 0.74 I Q points, respectively. Dr. Caplan did not testify, however, that this interpretation of t he studies’ findings formed the underpinning of his calculations. Further, assuming that Dr. Caplan, in fact, determi ned that the studies show that every 1 μg/dL increase in a BLL leads to a loss of 0.62 or 0.74 IQ points, it is not readily

discernable from the content of the studies that th ese are reliable determinations, i.e. , that- 63 -

these are determinations reliably supported by info rmation or findings in the studies. With respect to the Lanphear study, the issue is plainly not that Dr. Caplan used the study to

make calculations or that he used information in th e study and extrapolated to achieve a result. The question is whether his calculations i nvolve use of information in the study in a way that produces reliable results. To be sure, the Lanphear and Canfield studies refer to losses of 6.2 or 7.4 IQ points, respectively, se e 113 Env’t Health Persps. at 898; 348 New Eng. J. of Med. at 1517, and it is possible Dr. Caplan’s approach is a reliable use of the information. But without a full explanation of his methodology, including the reasons for his choices, even though it is possible to disc ern the basis of the calculations, we cannot

determine whether it was an abuse of discretion for the circuit court to preclude this aspect of Dr. Caplan’s testimony. It could well be that, once the parties have adduce d additional information from Dr. Caplan concerning his use of the studies and the ci rcuit court has been given an opportunity to assess his methodology, Dr. Caplan’s testimony w ith respect to Ms. Oglesby’s IQ loss based on one or both of the studies may be admissib le. On remand, should Ms. Oglesby seek to introduce Dr. Caplan’s testimony concerning her IQ loss, the circuit court, at a new hearing, will have an opportunity to assess Dr. Cap lan’s use of the studies and the reliability of his methodology. For these reasons, we remand t he case for a hearing under Rochkind, 471 Md. 1, 236 A.3d 630, for the circuit court to d etermine whether the calculations that Dr. Caplan employed using the Lanphear study are re liable and to assess Dr. Caplan’s use of the Canfield study and the reliability of his me thodology with respect to it, should Ms. Oglesby seek to introduce evidence concerning her I Q loss at trial.- 64 - III. Summary Judgment Was Not Warranted Having concluded that the circuit court abused its discretion in granting the motion to preclude, we hold that the circuit court erred i n granting summary judgment. The circuit court’s ruling that Ms. Oglesby was unable to prove negligence without Dr. Caplan’s testimony on causation was not warranted. Even wit hout Dr. Caplan’s testimony (which should not have been excluded in its entirety), bas ed on other evidence, Ms. Oglesby presented sufficient evidence that the property was a source of her exposure to lead to satisfy the first link of the causal chain. Dr. Ca plan’s testimony, along with other evidence,

satisfied the second and third causal links. In su m, Ms. Oglesby presented sufficient evidence that there was a reasonable probability, i.e. , a fair likelihood, that the apartment at 2000 East North Avenue was a source of her expos ure to lead-based paint and a significant contributing factor to her alleged inju ries, other than IQ loss, to establish a prima facie case for negligence. See Rowhouses, Inc. v. Smith , 446 Md. 611, 657, 133 A.3d 1054, 1082 (2016). Expert testimony is not necessarily required to “ru le in a property” as a source of exposure to lead. See id. at 665-66, 133 A.3d at 1 087; Ross, 430 Md. at 669, 63 A.3d at 13. In Rowhouses, 446 Md. at 668, 133 A.3d at 1088 , we held that the trial court erred in granting summary judgment in the defendant’s favor as to the plaintiff’s negligence claim because, even without direct evidence that the subj ect property contained lead-based paint and without expert testimony as to the source of th e plaintiff’s lead exposure, “there was

sufficient circumstantial evidence from which a tri er of fact could conclude that the [subject p]roperty contained lead-based paint[.]” We determ ined that, for purposes of causation in- 65 -

lead-based paint cases at the summary judgment phas e, “a reasonable probability requires a showing that is less than ‘more likely than not,’ but more than a mere ‘possibility.’” Id. at 655, 133 A.3d at 1080-81 (footnote omitted). We concluded that, “in a lead-based paint case, a subject property is a reasonable probable s ource of a plaintiff’s lead exposure where there is a fair likelihood that the subject propert y contained lead-based paint and was a source of the lead exposure.” Id. at 659, 133 A.3d at 1083. We explained that, “when proceeding under a Dow [33] theory of causation, where there is no direct evidence that a property contain ed lead-based paint, as a necessary part of the circumstantial evidence, the plaintiff must, by process of elimination, rule out other potential sources and demonstrate that the property at issue is the only source of exposure. See Rowhouses, 446 Md. at 659-60, 133 A.3d at 1083. As to ruling out other reasonably probable sources of lead, we stated that, “[a]t the summary judgment stage, although expert witness testimony may be helpful to rule out anothe r property as a reasonable probable source, it is not necessary.” Id. at 661, 133 A.3d at 1084 (citation omitted). 34 In contrast,

33 In Dow, 144 Md. App. at 76-77, 796 A.2d at 144-45, the Appellate Court held that the trial court erred in granting a motion for summ ary judgment where, in opposition to the motion, the plaintiffs set forth circumstantial evi dence that, if believed, “could establish that the chipping and peeling paint inside [the sub ject property] was the only possible source of [the plaintiff]’s lead poisoning” and thu s caused the plaintiff’s alleged injuries.

34 “[C]ircumstantial evidence that rules out other rea sonably probable sources may take the form of a lay witness’s testimony at a dep osition or an averment in an affidavit that a property other than the subject property did not contain deteriorated, chipping, or flaking paint and was in good condition.” Rowhouse s, 446 Md. at 661, 133 A.3d at 1084. Or, a lay witness’s testimony or affidavit could ru le out other reasonably probable sources of lead, including environmental sources such as so il, painted toys, and the like, by stating that the plaintiff did not have contact with such s ources. See id. at 661-62, 133 A.3d at 1084.- 66 -

where a plaintiff produces direct evidence that a p roperty contains lead, the ruling out of other potential sources, by expert testimony or oth erwise, is not required. See, e.g., Hamilton v. Kirson, 439 Md. 501, 536-37, 96 A.3d 71 4, 735-36 (2014) (Where there is no direct evidence that the subject property contained lead, the plaintiff “may prove circumstantially that the subject property containe d lead-based paint in a number of ways[,]” including, but not limited to, relying on a Dow theory of causation by excluding other reasonably probable sources of lead.). In Rogers, 453 Md. at 256, 272-73, 160 A.3d at 1210 , 1220, where without ruling out other possible sources of exposure, the plainti ff produced evidence, including a 1976 positive test for lead at the subject property (20 years before his residency), we held that the evidence was sufficient to establish the subjec t property as a reasonably probable source of lead exposure and that summary judgment was impr operly granted. We explained that “[t]he 1976 interior lead testing, paired with the lack of evidence showing full lead abatement, [gave] rise to a reasonable inference th at [the subject property’s] interior still contained lead-based paint when [the plaintiff] liv ed there.” Id. at 271, 160 A.3d at 1218- 19. We stated that, in a lead-based paint case, “a plaintiff is not required to show that one source of his lead exposure contributed to his inju ry to a greater degree than another” and that, “[o]nce a plaintiff has established a propert y as a reasonably probable source of his lead exposure, a defendant cannot avoid liability b y pointing to other properties that also exposed the plaintiff to lead.” Id. at 274, 160 A. 3d at 1221 (citation omitted). As Rowhouses, 446 Md. at 665-66, 133 A.3d at 1087, and Rogers, 453 Md. at 274, 160 A.3d at 1221, demonstrate, with direct evidence of lead in the building, Ms. Oglesby- 67 -

did not necessarily need expert testimony to rule o ut other properties as reasonable probable sources where she produced sufficient admi ssible evidence to rule in 2000 East North Avenue as a reasonable probable source at the summary judgment stage. Because

we hold that the circuit court abused its discretio n in excluding Dr. Caplan’s opinion that Ms. Oglesby’s exposure to lead at the property was a significant contributing factor to her injuries other than IQ loss, there is sufficient ev idence to establish a reasonable probability

as to each of the links in the causation chain and to preclude summary judgment.

IV. Conclusion For the reasons stated herein, we reverse the judgm ent of the circuit court and remand the case for trial or further proceedings un der Rochkind, 471 Md. 1, 236 A.3d 630, should Ms. Oglesby elect to present expert testimon y as to IQ loss. As in Frankel, 480 Md. at 714-15, 281 A.3d at 711, in light of the finding s made by the trial judge in ruling on the motions, this case should be assigned to a differen t trial judge for all further proceedings.

JUDGMENT OF THE APPELLATE COURT OF MARYLAND REVERSED. CASE REMANDED TO THAT COURT WITH INSTRUCTION TO REMAND THE CASE TO THE CIRCUIT COURT FOR BALTIMORE CITY FOR TRIAL OR OTHER FURTHER PROCEEDINGS CONSISTENT WITH THIS OPINION. RESPONDENTS TO PAY COSTS.